WO2014170981A1 - 水処理システム - Google Patents
水処理システム Download PDFInfo
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- WO2014170981A1 WO2014170981A1 PCT/JP2013/061461 JP2013061461W WO2014170981A1 WO 2014170981 A1 WO2014170981 A1 WO 2014170981A1 JP 2013061461 W JP2013061461 W JP 2013061461W WO 2014170981 A1 WO2014170981 A1 WO 2014170981A1
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- unit
- water
- ions
- ion
- desalting
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 378
- 150000002500 ions Chemical class 0.000 claims abstract description 363
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 40
- 238000010612 desalination reaction Methods 0.000 claims abstract description 21
- 230000008929 regeneration Effects 0.000 claims abstract description 16
- 238000011069 regeneration method Methods 0.000 claims abstract description 16
- 239000003014 ion exchange membrane Substances 0.000 claims abstract description 3
- 238000011033 desalting Methods 0.000 claims description 128
- 238000001556 precipitation Methods 0.000 claims description 62
- 238000000926 separation method Methods 0.000 claims description 27
- 239000007787 solid Substances 0.000 claims description 26
- 239000006228 supernatant Substances 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 18
- 238000001816 cooling Methods 0.000 claims description 17
- 239000002244 precipitate Substances 0.000 claims description 10
- 230000018044 dehydration Effects 0.000 claims description 9
- 238000006297 dehydration reaction Methods 0.000 claims description 9
- 150000008044 alkali metal hydroxides Chemical class 0.000 claims description 3
- 230000001376 precipitating effect Effects 0.000 claims description 3
- 238000004062 sedimentation Methods 0.000 claims description 3
- 238000000151 deposition Methods 0.000 claims 1
- 239000003002 pH adjusting agent Substances 0.000 claims 1
- 230000008030 elimination Effects 0.000 abstract 5
- 238000003379 elimination reaction Methods 0.000 abstract 5
- 238000003795 desorption Methods 0.000 abstract 1
- 239000012528 membrane Substances 0.000 description 31
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 31
- 238000001223 reverse osmosis Methods 0.000 description 27
- 239000000377 silicon dioxide Substances 0.000 description 16
- 238000011084 recovery Methods 0.000 description 12
- 238000004088 simulation Methods 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- -1 Na + Chemical class 0.000 description 7
- 229910001420 alkaline earth metal ion Inorganic materials 0.000 description 6
- 150000001450 anions Chemical class 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 238000007599 discharging Methods 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 239000005416 organic matter Substances 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- 239000003011 anion exchange membrane Substances 0.000 description 4
- 238000005341 cation exchange Methods 0.000 description 4
- 150000001768 cations Chemical class 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 239000012141 concentrate Substances 0.000 description 4
- 229910001385 heavy metal Inorganic materials 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229910021645 metal ion Inorganic materials 0.000 description 4
- 239000002351 wastewater Substances 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 239000010842 industrial wastewater Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000012466 permeate Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 229910001413 alkali metal ion Inorganic materials 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000002328 demineralizing effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000013505 freshwater Substances 0.000 description 2
- 239000008235 industrial water Substances 0.000 description 2
- 238000006386 neutralization reaction Methods 0.000 description 2
- 238000010979 pH adjustment Methods 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000010865 sewage Substances 0.000 description 2
- 239000010802 sludge Substances 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005115 demineralization Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000011143 downstream manufacturing Methods 0.000 description 1
- 238000000909 electrodialysis Methods 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 239000008400 supply water Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Images
Classifications
-
- 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
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
-
- 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
- B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
- B01D61/428—Membrane capacitive deionization
-
- 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
- B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
- B01D61/44—Ion-selective electrodialysis
-
- 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
- B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
- B01D61/44—Ion-selective electrodialysis
- B01D61/46—Apparatus therefor
- B01D61/468—Apparatus therefor comprising more than two electrodes
-
- 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
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
- C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
- C02F1/4695—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis electrodeionisation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2313/00—Details relating to membrane modules or apparatus
- B01D2313/34—Energy carriers
- B01D2313/345—Electrodes
-
- 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
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/4604—Treatment of water, waste water, or sewage by electrochemical methods for desalination of seawater or brackish water
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/46—Apparatus for electrochemical processes
- C02F2201/461—Electrolysis apparatus
-
- 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
Definitions
- the present invention relates to a water treatment system that performs desalination treatment.
- Industrial wastewater drained from the plant is subjected to purification treatment such as removal of heavy metal components and suspended particles, and decomposition and removal of organic matter.
- purification treatment such as removal of heavy metal components and suspended particles, and decomposition and removal of organic matter.
- the purified treated water is reused as industrial water.
- a desalting process is performed to remove ions contained in the waste water.
- Patent Document 1 is installed at a downstream of a liquid-flow condenser that removes and collects (regenerates) ion components in water to be treated by using an electrostatic force. Discloses a desalination apparatus in combination with a reverse osmosis membrane apparatus.
- ions contained in water monovalent cations such as Na + , K + and NH 4 + and anions such as Cl ⁇ and F ⁇ are ions having high solubility in water.
- divalent metal ions such as Ca 2+ and Mg 2+ and anions and silica ions such as SO 4 2 ⁇ and CO 3 2 ⁇ are components constituting the scale. Since salts and silica to which ions of components constituting the scale are bonded have low solubility in water, they are likely to precipitate as scale.
- the above-described liquid-flow capacitor has low selectivity for the valence of ions to be removed. For this reason, not only the ions (scale component ions) that become the scale components described above, but also other ions (for example, components that are difficult to precipitate as scales such as Na + and Cl ⁇ ) must be removed at the same time.
- water containing a relatively large amount of scale component ions is treated using the desalination apparatus of Patent Document 1, water with high scale component ions is sent to the reverse osmosis membrane device without sufficient removal. Will end up.
- An object of the present invention is to provide a water treatment system that can suppress the generation of scale more effectively by increasing the removal rate of scale component ions.
- the water treatment system includes a desalting unit and an ion selective removing unit.
- the desalting unit is installed between a pair of opposing electrodes that are charged with opposite polarities, a channel that is positioned between the electrodes and that allows water containing ions to flow therethrough, and the channel side of each of the electrodes.
- the ion selective removal unit is provided on the downstream side or the upstream side of the desalting unit, and the removal rate of divalent or higher ions serving as the inner scale component of the ions is higher than the removal rate of the monovalent ions. It is relatively high and separates and removes the divalent or higher ions from the water containing the ions.
- the ion selective removing unit is provided on the downstream side of the desalting unit, and the ion selective removing unit is treated water after being desalted by the desalting unit.
- the divalent or higher ion can be removed.
- the polyvalent ion concentrated water containing the divalent or higher ions separated by the ion selective removal unit is discharged from the ion selective removal unit and supplied to the upstream side of the desalting unit. Is preferred.
- the ion selective removal unit is provided on the upstream side of the desalting unit, and the desalting unit includes the divalent or higher ions separated by the ion selective removing unit. Multivalent ion concentrated water can be received and the polyvalent ion concentrated water can be desalted. In this case, it is more preferable that the treated water discharged from the desalting unit in the desalting process is supplied to the upstream side of the ion selective removing unit.
- the treated water contains scale component ions such as alkaline earth metal ions (Ca 2+ , Sr 2+ , Ba 2+ ), Mg 2+ , sulfate ions, carbonate ions, phosphate ions, sulfide ions, and F ⁇ . It is. When the salt of the above components becomes supersaturated, it precipitates as a scale. On the other hand, if at least divalent metal ions (alkaline earth ions or Mg 2+ ) are removed from the above ions, even if monovalent scale component ions such as F ⁇ and HCO 3 ⁇ remain, scale precipitation Can be prevented.
- the ion selectivity removing unit in the water treatment system is specifically a nanofilter having ion selectivity.
- the present inventors have different removal rates with nanofilters depending on the type of ions, and can significantly remove the removal rate of divalent or higher ions (alkaline earth metal ions, Mg 2+ , SO 4 2 ⁇ , etc.) as scale components. Focused on.
- a desalting unit that performs electrostatic desalting treatment and an ion selective removing unit are combined.
- desalting and regeneration are alternately repeated, and therefore, scale is unlikely to be generated in the electrode and the ion exchange membrane.
- there is no valence selectivity of removed ions and all ions in the water to be treated are removed. Further, since a large amount of power is required for the processing, the operation cost is high.
- the ion selective removal part has a high removal rate of divalent or higher ions (scale component ions) of 80% or higher.
- the ion selective removal unit has a low removal rate of monovalent ions not constituting the scale, for example, about 45 to 80%.
- the water treatment system of the present invention can separate and remove divalent or higher ions contained in water while allowing a certain amount of monovalent ions not constituting the scale to pass. The separation effect increases as the difference between the removal rate of divalent and higher ions and the removal rate of monovalent ions increases.
- “separating and removing divalent or higher ions” in the present invention means that divalent or higher ions are removed from water by 80% or more, desirably 98% or more, more desirably 99.8% or more. Refers to the state.
- the ion selective removal unit concentrates ions.
- monovalent ions such as alkali metal ions and anions such as Cl ⁇ , Br ⁇ , I ⁇ and NO 3 ⁇ do not cause problems such as scale generation even if they remain in the treated water.
- anions such as Cl ⁇ , Br ⁇ , I ⁇ and NO 3 ⁇
- scale component ions are concentrated by the ion selective removal unit, there is a drawback that scale is easily generated. Therefore, which of the desalting part and the ion selective removing part is installed upstream is determined according to the advantages and disadvantages of the desalting part and the ion selective removing part and the quality of the water to be treated. Is done.
- Ratio of divalent or higher ions to total ion concentration in treated water (divalent or higher ion concentration / total ion concentration), or ratio of bivalent or higher ion concentration to monovalent ion concentration (bivalent or higher ion concentration / Since the monovalent ion concentration is high and the scale component including divalent or higher ions is near the saturation solubility or higher than the saturation solubility, the desalting unit is provided on the upstream side. In this configuration, after the rough removal in which the concentration of divalent or higher ions is reduced to some extent in the desalting unit, the ions of divalent or higher is selectively removed in the ion selective removal unit.
- the removal rate of divalent or higher ions in the water treatment system can be increased, and scale generation at the ion selective removal unit can be effectively prevented.
- the removal rate of divalent or higher ions can be further increased.
- an ion selective removal unit is provided on the upstream side.
- the concentrated water by the ion selective removing unit is processed in the desalting unit, the amount of water supplied to the desalting unit is reduced. For this reason, while reducing an apparatus volume, it is possible to reduce the electric power for operating a desalination part.
- the ion removal rate can be further increased and the water recovery rate of the water treatment system can be further increased.
- the scale component containing divalent or higher ions is near saturation solubility
- either a configuration in which the desalting part is provided on the upstream side or a structure in which the ion selective removal unit is provided on the upstream side is adopted. Also good. In this case, it sets suitably considering the operating cost and the requirements for the water quality after treatment in each of the desalting unit and the ion selective removing unit.
- the treated water and the water after removal of the divalent or higher ions by the ion selective removing unit are received and received.
- An ion concentrator for concentrating the ions in water may be installed.
- the ion concentrating unit includes at least one of a desalting apparatus, a cooling tower, and a boiler.
- the concentration of divalent or higher ions in the treated water by the water treatment system of the present invention is greatly reduced. Even if this treated water is treated or used in a device (ion concentrating unit) that concentrates ions in the system, such as a reverse osmosis membrane device or a cooling tower, scale generation in the ion concentrating unit is suppressed. be able to.
- a device ion concentrating unit
- an alkali metal hydroxide is provided in the water after the divalent or higher ions have been removed, downstream of the desalting unit and the ion selective removing unit and upstream of the ion concentrating unit. It is preferable that a pH adjusting unit for adjusting the pH of the water after being charged and the divalent or higher ions are removed is installed.
- silica In the water after the scale component ions are treated in the desalting part and the ion selective removing part, ionic silica and non-ionized silica remain. These are also scale components.
- Silica has a different dissolution state depending on pH, and is extremely soluble in water as ionic silica at pH 9 or higher.
- silica is dissolved in the treated water by appropriately adjusting the pH of the treated water by the pH adjusting unit installed downstream of the desalting unit and the selective removing unit. Thereby, generation
- the desalting unit is connected to a separation unit that receives the concentrated water discharged from the desalting unit in the regeneration process
- the separation unit includes a precipitation unit that precipitates the divalent or higher ions in the concentrated water as a solid, and a dehydration unit that separates the solid from the water containing the solid discharged from the precipitation unit.
- the solid can be a separate recovery comprising from concentrated water such as scale component ions such as CaCO 3 or CaSO 4. Furthermore, the water recovery rate can be further improved by circulating the separated water to the desalting unit or the ion selective removing unit.
- a separation unit including a dehydration unit for separating the solid is installed, and the supernatant discharged from the precipitation unit is fed to the desalting unit or the ion-selective removal unit to be desalted. It is also good.
- the concentration of the scale component ions is adjusted before flowing into the desalting unit and the ion selective removal unit by adopting the above configuration. It is possible to reduce the scale, and it is possible to prevent the generation of scale in the ion selective removal unit or the ion concentration unit.
- the water treatment system of the present invention by combining the ion selective removal unit and the desalination unit by electrostatic desalting, ions having a valence of 2 or more can be separated and removed from the treated water with high efficiency. For this reason, even when the apparatus (ion concentration part) which concentrates ion downstream is installed, generation
- FIG. 1 is a schematic diagram of a water treatment system according to the first embodiment of the present invention.
- the water treatment system 1 of 1st Embodiment is equipped with the desalination part 10 and the ion selective removal part 20 in an order from the upstream of to-be-processed water.
- the water to be treated includes alkali metal ions such as Na + and K + , alkaline earth metal ions such as Ca 2+ and Ba 2+ , cations such as Mg 2+ , F ⁇ , Cl ⁇ , Br ⁇ , I ⁇ and NO 3.
- Anions such as ⁇ , SO 4 2 ⁇ , HSO 4 ⁇ , SO 3 2 ⁇ , HSO 3 ⁇ , CO 3 2 ⁇ , HCO 3 ⁇ , PO 4 3 ⁇ , HS ⁇ , S 2 ⁇ are included.
- the ion enumerated above is an illustration and is not limited to these.
- alkaline earth metal ions Ca 2+ , Sr 2+ , Ba 2+ ), Mg 2+ , sulfate ions (SO 4 2 ⁇ , SO 3 2 ⁇ ), carbonate ions (HCO 3 ⁇ , CO 3 2 ⁇ ) , Phosphate ions (PO 4 3 ⁇ ), sulfide ions (HS ⁇ , S 2 ⁇ ), and F ⁇ are scale component ions.
- concentration of the salt containing the scale component ions in water exceeds the saturation solubility
- scale is generated.
- the time from the salt concentration exceeding the saturation solubility to the scale generation varies depending on conditions such as ion concentration and pH.
- Scale generation can be prevented if alkaline earth ions or Mg 2+ , which are at least divalent metal ions, are removed from the above ions. Therefore, Takamere the removal rate of a valence of two or more ions in the water treatment system 1, F - and HCO 3 - as a monovalent scale component ions such as remaining, thereby preventing scale deposition.
- the ion concentration / divalent ion concentration or the total ion concentration of bivalent or higher, or the ion concentration of bivalent or higher / monovalent ion concentration is high. Therefore, water to be treated is treated in the vicinity of the saturation solubility of the scale component that contains divalent or higher ions or higher than the saturation solubility. Specifically, the water to be treated is blowdown water, mine wastewater, desulfurization wastewater and the like drained from the cooling tower. Said to-be-processed water is a property which concerns about generation
- a discharge path 16 is provided on the downstream side of the desalting unit 10.
- the discharge path 16 is branched into a treated water discharge path 17 and a concentrated water discharge path 18 in the middle of the path.
- Valves V1 and V2 are installed in the treated water discharge path 17 and the concentrated water discharge path 18, respectively.
- FIG. 2 is a schematic view of the desalting unit.
- the desalting unit 10 includes a pair of opposed porous electrodes 11 and 13 and a flow path 15 through which supply water can flow between the electrodes.
- An anion exchange membrane 12 is installed on the side surface of the electrode 11 and a cation exchange membrane 14 is installed on the side surface of the electrode 13.
- the ion selectivity removing unit 20 is connected to the treated water discharge path 17.
- the ion selective removal unit 20 is an apparatus that can separate divalent or higher valent ions from water containing various ions with high yield.
- the ion selectivity removing unit 20 is a device including a nanofilter having ion selectivity.
- An upstream side of the nanofilter is a concentration unit, and a downstream side is a processing unit.
- the nanofilter is a filter having a large number of pores of about 1 to 2 nm.
- the removal rate (separation rate) of divalent or higher ions of the nanofilter that can be used in this embodiment is 80% or higher, preferably 98% or higher, more preferably 99.8% or higher.
- the removal rate of ions is 45 to 80%.
- the ion selective removal unit 20 includes a removal water discharge unit 21 and a multivalent ion concentrated water discharge unit 22.
- the removed water discharge unit 21 is connected to the processing unit.
- the multivalent ion concentrated water discharge unit 22 is connected to the concentration unit.
- a circulating unit 30 that connects the polyvalent ion concentrated water discharge unit 22 and the upstream pipe of the desalting unit 10 is provided. It may be installed.
- Desalting step A voltage is applied to the electrodes 11 and 13 so that the electrode 11 of the desalting unit 10 is positive and the electrode 13 is negative.
- the above energized state is referred to as “positive”.
- the valve V1 is opened and the valve V2 is closed.
- the treated water with reduced ion concentration is discharged from the desalting unit 10 as treated water, passes through the treated water discharge passage 17, and is discharged out of the system of the desalting treatment apparatus and collected.
- Regeneration process After the desalting step is performed for a predetermined time, a voltage is applied to each of the electrodes 11 and 13 so that the electrode 11 becomes negative and the electrode 13 becomes positive. That is, the electrode is in a “reverse” energized state. At the same time that the electrodes 11 and 13 are turned on in reverse, the valve V1 is closed and the valve V2 is opened. Thereby, the regeneration process is started.
- the ions adsorbed in the desalting process are desorbed from the electrodes 11 and 13 and returned to the flow path 15.
- the cations and anions that have returned to the flow channel 15 cannot accumulate through the anion exchange membrane 12 and the cation exchange membrane 14, respectively, and thus accumulate in the flow channel 15.
- clean water fresh water
- the ions released into the flow path 15 are discharged from the desalting unit 10 together with fresh water.
- the water discharged from the desalting unit 10 passes through the concentrated water discharge path 18 as concentrated water and is discharged out of the water treatment system 1.
- the desalting step and the regeneration step described above are performed alternately every predetermined time.
- the desalting step and the regeneration step are each carried out for 1 to 60 minutes, preferably 1 to 10 minutes.
- ions having a valence of 2 or more are removed by the ion selective removal unit, water containing a valence of 2 or more in the concentration unit (multivalent ion concentrated water), and in the downstream processing unit. It is separated into water from which most of the ions having a valence of 2 or more are removed (the concentration of ions having a valence of 2 or more is reduced to 2% or less).
- the multivalent ion concentrated water is supplied to the upstream side of the desalting unit 10 through the circulation unit 30.
- the concentrated polyvalent ion water supplied to the upstream side of the desalting unit 10 is mixed with the water to be treated, and desalted in the desalting step in the desalting unit 10.
- the circulation unit is not installed, the polyvalent ion concentrated water is discharged from the polyvalent ion concentrated water discharge unit 22 to the outside of the water treatment system 1.
- Table 1 shows a simulation result when water containing ions is treated in the water treatment system of FIG.
- Table 1 shows the concentrations of ions and total dissolved solids (TDS) contained in the water to be treated (mine wastewater) and the water flowing through the pipes L 1-1 to L 1-5 .
- the positions of the pipes L 1-1 to L 1-5 are as follows.
- L 1-1 Demineralization section inlet piping (downstream of the circulating section connection position)
- L 1-2 Treated water discharge path
- L 1-3 Concentrated water discharge path
- L 1-4 Circulation section piping
- L 1-5 Removed water discharge section piping
- Desalting section water recovery rate 80%, ion removal rate 80%.
- Ion selective removal part water recovery rate 85%, divalent or higher ion removal rate 98%. Monovalent ion removal rate of 60%.
- Comparative Example 1 a simulation was performed when water having the same properties as in the above example was subjected to water treatment using a water treatment system having only a desalting unit.
- Table 2 shows the TDS concentration and the ion concentration contained in the water to be treated, the treated water in the desalted portion, and the concentrated water.
- the simulation conditions were such that the water recovery rate of the desalting part was 80% and the ion removal rate was 80%.
- Example 1 the TDS concentration in the treated water of L 1-5 is reduced as compared with the water treatment system of Comparative Example 1 in which treated water of the same property is treated.
- the concentrations of Ca 2+ , Mg 2+ , and SO 4 2 ⁇ which are divalent or higher ions constituting the scale, are greatly reduced.
- HCO 3 ⁇ which is a scale component ion remains to some extent in the treated water (L 1-5 ), but scale deposition does not occur because the divalent metal ion concentration is low.
- water treatment is performed with the water regeneration treatment system having the configuration of the first embodiment. If performed, the concentration of divalent or higher ions can be made extremely low, which is advantageous in suppressing scale precipitation.
- an ion concentrating unit 40 may be installed on the downstream side of the removed water discharging unit 21 of the ion selective removing unit 20 as shown in FIG.
- the ion concentrating unit 40 is an apparatus that further concentrates ions in water that have passed through the desalting unit 10 and the ion selective removing unit 20.
- Examples of the ion concentrating unit 40 include a desalting apparatus, a boiler, and a cooling tower.
- a reverse osmosis membrane device As a desalting device, a reverse osmosis membrane device, an electrodialysis device (ED), an electric regeneration type pure water device (EDI), an ion exchange resin device, and the same desalting device as the desalting unit 10 (electrostatic desalting device) Etc. can be installed.
- ED electrodialysis device
- EDI electric regeneration type pure water device
- ion exchange resin device an ion exchange resin device
- the reverse osmosis membrane device is a device having a reverse osmosis membrane having pores (about 0.5 nm) smaller than the nanofilter and having a higher ion removal rate than the nanofilter.
- ions monovalent ions
- a reverse osmosis membrane device is installed as the ion concentrating unit 40, ions (monovalent ions) remaining in the water that has passed through the desalting unit 10 and the ion selective removing unit 20 are removed by the reverse osmosis membrane device.
- a plurality of reverse osmosis membrane devices may be connected in series. Since the concentration of divalent or higher ions serving as a scale in water treated by the reverse osmosis membrane device by the water treatment system 1 of the present embodiment is greatly reduced, scale deposition in the reverse osmosis membrane device is suppressed.
- an evaporator or a crystallizer may be installed downstream of the concentration unit side of the reverse osmosis membrane device.
- water is evaporated from the concentrated water, and ions contained in the concentrated water are precipitated as a solid and collected as a solid.
- a pH adjusting unit 50 is further installed downstream of the ion selective removing unit 20 and upstream of the ion concentrating unit 40 as shown in FIG. It is preferable.
- the water to be treated contains ionic silica and non-ionized solid silica as other scale components. Since ionic silica has a low removal rate in the desalting unit and the ion selective removing unit, it passes through the water treatment system 1. Silica that is not ionized also passes through the water treatment system 1.
- the treated water after being treated by the water treatment system 1 contains silica-like ions and solid silica. The solubility of silica present in water varies depending on the pH, and is extremely soluble in water as ionic silica when the pH is 9 or more.
- the pH adjusting unit 50 is alkaline in water so that the pH of water passing between the ion selective removing unit 20 and the ion concentrating unit 40 (measured at a pH not shown in FIG. 3) is 9 or more.
- the alkaline agent is an aqueous solution of an alkali metal hydroxide such as Na or K.
- a boiler or a cooling tower When a boiler or a cooling tower is installed as the ion concentrating unit 40, it may be configured to be combined with a desalting apparatus and treated water from the desalting apparatus is supplied to the boiler or the cooling tower.
- a reverse osmosis membrane device water (water from which ions have been removed) discharged from the evaporator and crystallizer installed downstream of the concentration unit of the reverse osmosis membrane device is sent to a cooling tower or boiler. It is good also as a structure supplied.
- the water treatment system 1 of this embodiment produces
- Second Embodiment 3 and 4 are schematic views of a water treatment system according to the second embodiment of the present invention.
- water whose scale component including divalent or higher ions is near saturation solubility or lower than saturation solubility is a treatment target.
- a treatment target For example, river water, sewage treated water, brine, factory effluent, factory effluent treated water and the like.
- Sewage treated water and industrial wastewater treated water are water after organic substances and harmful substances are removed.
- a pretreatment section and an organic matter treatment section may be installed upstream of the water treatment system.
- oil, heavy metals, suspended particles and the like in the water to be treated are removed from the water to be treated.
- the organic matter treatment unit is configured by appropriately combining a biological treatment unit that decomposes and removes organic matter using microorganisms, a chemical oxidation treatment unit that chemically oxidizes organic matter, activated carbon, and an ultraviolet treatment device. .
- 3 and 4 includes a desalting unit 110 and an ion selective removing unit 120 having the same configuration as that of the first embodiment.
- the ion selective removal unit 120 is installed upstream of the desalting unit 110.
- an ion concentrating unit 140 and a pH adjusting unit 150 may be provided on the downstream side of the water treatment systems 101 and 201.
- the removed water discharging unit 121 of the ion selective removing unit 120 is connected to the ion concentrating unit 140.
- the polyvalent ion concentrated water discharge unit 122 of the ion selective removal unit 120 is connected to the desalting unit 110.
- the treated water discharge path 117 of the desalting unit 110 is connected to the ion concentrating unit 140.
- the treated water discharge path 117 of the desalting unit 110 is connected to a pipe on the upstream side of the ion selective removal unit 120 through the circulation unit 130.
- the configuration shown in FIG. 3 or 4 is selected according to the quality of the water to be treated. In the case where the concentration of divalent or higher ions in the water to be treated is very low and the concentration of divalent or higher ions in the treated water of the desalting unit 110 is sufficiently reduced, the circulation unit is not provided as shown in FIG. Also good.
- (A) Treatment in the ion selective removal unit The water to be treated flows into the ion selective removal unit 120. Similar to the first embodiment, the ion selectivity removing unit 120 separates the water to be treated into multivalent ion-concentrated water and water having a divalent or higher ion concentration reduced. The water in which the divalent or higher ion concentration is reduced is discharged from the ion selective removing unit 120 through the removed water discharging unit 121. The discharged water is supplied to the ion concentrating unit 140. The polyvalent ion concentrated water is discharged from the ion selective removal unit 120 through the polyvalent ion concentrated water discharge unit 122 and is supplied to the desalting unit 110.
- the desalting unit 110 performs the desalting step and the regeneration step similar to those in the first embodiment, and treats the polyvalent ion concentrated water.
- divalent or higher ions in the polyvalent ion concentrated water are adsorbed and removed in the desalting step.
- the concentrated water produced by the regeneration process is discharged out of the water treatment system 101 in FIG. 3 or the water treatment system 201 in FIG. 4 through the concentrated water discharge path 118.
- the treated water is supplied to the ion selective removing unit 120 through the treated water discharge path 117 and the circulation unit 130.
- the supplied treated water flows into the ion selectivity removing unit 120 together with the treated water. That is, in the water treatment system 101 of FIG. 3, the polyvalent ion concentrated water passes through the desalting unit 110 and is then circulated to the ion selective removal unit 120.
- the treated water desalted in the desalting step is water having a reduced concentration of divalent or higher ions discharged from the ion selective removal unit 120 through the treated water discharge path 117. Join. Thereafter, the treated water is fed to the ion concentrating unit 140 together with water in which the ion concentration of two or more valences is reduced.
- Table 3 shows the simulation results when water containing ions is treated in the water treatment system of FIG. Table 3, the water to be treated (industrial wastewater) and the pipe L 2-1 ⁇ L 2-5 concentration and total dissolved solids of ions contained in the water flowing through the (TDS: Total Dissolved Solids) in concentrations shown Yes.
- the positions of the pipes L2-1 to L2-5 are as follows.
- L2-1 Ion selectivity removal unit inlet piping (downstream of the circulating unit connection position)
- L2-2 Desalination part inlet piping (connected to the polyvalent ion concentrated water discharge part)
- L 2-3 Concentrated water discharge path
- L 2-4 Circulation section piping (connected to treated water discharge path)
- L 2-5 Removal water discharge part piping of ion selective removal part The simulation was performed under the following conditions. Desalting section: water recovery rate 80%, ion removal rate 80%.
- Ion selective removal part water recovery rate 85%, divalent or higher ion removal rate 98%. Monovalent ion removal rate of 60%.
- Example 2 As Comparative Example 2, a simulation was performed when water having the same properties as in Example 2 was subjected to water treatment using a water treatment system having only a desalting unit. Table 4 shows the TDS concentration and the ion concentration contained in the water to be treated, the treated water in the desalted portion, and the concentrated water. The simulation conditions were such that the water recovery rate of the desalting part was 80% and the ion removal rate was 80%.
- Water treatment system of the second embodiment as compared with Comparative Example 2 of a water treatment system that processed the water to be treated in the same property, a divalent or more ions in the treated water of L 2-5 (Ca 2+, Mg 2+ , The concentration of SO 4 2 ⁇ ) is greatly reduced.
- the divalent or higher ion concentration in the treated water in L 2-4 is further reduced than in Table 3.
- the ion concentrating unit 140 includes a desalting apparatus, a boiler, and a cooling tower, and these may be combined.
- a reverse osmosis membrane device is employed as the desalting device, an evaporator or a crystallizer may be installed on the downstream side of the reverse osmosis membrane device.
- a pH adjusting unit 50 for adjusting the pH of water and suppressing silica precipitation is further installed on the upstream side of the ion concentrating unit 140 and on the downstream side of the water treatment system.
- adjusting the pH with the pH adjusting unit 50 it is possible to suppress the occurrence of scale when a reverse osmosis membrane device is installed at a later stage.
- ion removal is performed when the water to be treated is treated with a scale component that includes divalent or higher ions near saturation solubility or lower than saturation solubility. It is advantageous because the rate and water recovery rate can be increased.
- the ion concentration of bivalent or higher in the treated water discharged from the ion selective removing unit 120 Is greatly reduced. For this reason, generation
- the water treated by the water treatment systems 101 and 201 of the second embodiment can also be used as washing water because alkaline earth metal ions are reduced.
- FIG. 5 is a schematic diagram illustrating a configuration for separating and recovering Ca as a solid from the concentrated water of the desalting unit in the water treatment system of the first embodiment as the third embodiment of the present invention.
- the concentrated water discharge path 18 of the water treatment system 1 is connected to the separation unit 300.
- the separation unit 300 includes a precipitation unit 301 and a dehydration unit 302.
- FIG. 5 illustrates a case where CaCO 3 is recovered from the concentrated water containing Ca 2+ and CO 3 2 ⁇ as main scale component ions in the water treatment system of FIG.
- the separation unit 300 in FIG. 5 includes a first precipitation device 301 a and a second precipitation device 301 b as the precipitation unit 301.
- the concentrated water discharge path 18 is connected to the first precipitation device 301a, and the concentrated water of the desalting unit 10 is supplied to the first precipitation device 301a.
- Ca (OH) 2 is charged into the first precipitation device 301a for pH adjustment.
- CaCO 3 becomes supersaturated, CaCO 3 precipitates and precipitates at the bottom of the first precipitation device 301a.
- Heavy metals contained in the concentrated water also precipitate at the bottom of the first precipitation device 301a.
- the first precipitation device 301a and the second precipitation device 301b are connected.
- the supernatant liquid containing Ca 2+ is fed from the first precipitation device 301a to the second precipitation device 301b.
- Na 2 CO 3 is charged into the second precipitation device 301b, and Ca 2+ precipitates as CaCO 3 and precipitates at the bottom.
- the supernatant liquid in the second precipitation device 301b contains scale component ions that could not be separated by the first precipitation device 301a and the second precipitation device 301b.
- the supernatant of the second precipitation device 301 b is discharged from the second precipitation device 301 b and supplied to the upstream side of the desalting unit 10.
- the 2nd precipitation apparatus 301b may be connected to the treated water discharge path 17, and the supernatant liquid of the 2nd precipitation apparatus 301b may be supplied to the ion selective removal part 20.
- FIG. The supply destination of the supernatant can be appropriately selected according to the properties of the supernatant, the properties of the water to be treated, and the properties of the treated water in the desalting unit 10.
- the bottoms of the first precipitation device 301 a and the second precipitation device 301 b are connected to the dehydration unit 302.
- Water containing precipitates is discharged from the bottoms of the first precipitation device 301 a and the second precipitation device 301 b and fed to the dehydration unit 302.
- the dewatering unit 302 separates water and solids, and sludge containing CaCO 3 is recovered.
- the water separated by the dehydrating unit 302 is circulated to the first precipitation device 301a.
- FIG. 6 is a schematic diagram illustrating a configuration for separating and recovering Ca as a solid from the concentrated water of the desalting unit in the water treatment system of the second embodiment as the fourth embodiment of the present invention.
- FIG. 6 illustrates a case where CaCO 3 is recovered from the concentrated water containing Ca 2+ and CO 3 2 ⁇ as main scale component ions in the water treatment system of FIG.
- the configuration of the separation unit 400 is the same as that of the third embodiment.
- the supernatant of the second precipitation device 301 b is circulated upstream of the ion selective removal unit 120.
- the 2nd precipitation apparatus 301b may be connected to the piping between the ion selective removal part 120 and the desalination part 110, and the supernatant liquid of the 2nd precipitation apparatus 301b may be circulated to the desalination part 110.
- the supply destination of the supernatant can be appropriately selected according to the properties of the supernatant, the properties of the water to be treated, and the properties of the polyvalent ion concentrated water of the ion selective removal unit 120.
- the water after the sludge is recovered from the concentrated water in the desalting unit is circulated to the water treatment system, so that the water recovery rate can be further improved.
- FIG. 7 is a schematic diagram illustrating a configuration in which a separation unit is installed upstream of the water treatment system of the first embodiment as the fifth embodiment of the present invention.
- FIG. 7 is a configuration connected to the water treatment system of FIG. 1, and is an example in which scale component ions in the water to be treated are mainly Ca 2+ and CO 3 2 ⁇ .
- scale component ions in the water to be treated are mainly Ca 2+ and CO 3 2 ⁇ .
- the separation unit 500 of the fifth embodiment includes a precipitation unit 301 and a dehydration unit 302 as in the third embodiment.
- the supernatant of the second precipitation device 301b is fed to the desalting unit 10 of the first embodiment.
- Other configurations of the separation unit 500 are the same as those of the third embodiment.
- the circulation unit 30 is connected to a pipe between the second precipitation device 301 b and the desalting unit 10, and the polyvalent ion concentrated water of the ion selective removal unit 20 is sent to the desalting unit 10 together with the supernatant. Have been paid.
- the circulating unit 30 is connected to the first precipitation device 301a according to the property of the polyvalent ion concentrated water, the property of the water to be treated, and the property of the supernatant, and the polyvalent ion concentrated water is subjected to the first precipitation. It is good also as a structure supplied to the apparatus 301a.
- the configuration of the fifth embodiment is effective when Ca 2+ is water to be treated whose water quality exceeds the saturation concentration. If Ca 2+ concentration is very high treatment water flows into the water treatment system 1, it can not be sufficiently removed Ca 2+ in desalination unit 10, the ion selected in Ca 2+ concentration in the treated water desalination unit 10 is high It will flow into the property removing unit 20. In this case, since the Ca 2+ concentration on the concentration unit side of the ion selective removal unit 20 becomes high, there is a possibility that scale is generated in the ion selective removal unit 20. In such a case, the removal of scale components by the water treatment system 1 may be insufficient.
- FIG. 8 is a schematic diagram illustrating a configuration in which a separation unit is installed upstream of the water treatment system of the second embodiment as the sixth embodiment of the present invention.
- FIG. 8 is a configuration connected to the water treatment system of FIG. 3, and is an example in the case where the scale component ions in the for-treatment water are mainly Ca 2+ and CO 3 2 ⁇ .
- 6th Embodiment is good also as a structure which installed the separation part in the water treatment system of FIG.
- the separation unit 600 of the sixth embodiment includes a precipitation unit 301 and a dehydration unit 302 as in the third embodiment.
- the supernatant of the second precipitation device 301b is fed to the ion selective removal unit 120 of the second embodiment.
- Other configurations of the separation unit 600 are the same as those in the fourth embodiment.
- the concentrated water discharge path 118 is connected to the first precipitation device 301a, and the concentrated water of the desalting unit 110 is supplied to the first precipitation device 301a.
- the concentrated water discharge path 118 is connected to a pipe between the second precipitation device 301b and the ion selective removal unit 120 depending on the properties of the concentrated water, the properties of the water to be treated, and the properties of the supernatant.
- the concentrated water may be supplied to the ion selective removing unit 120.
- the pH in the precipitation part 301 is adjusted to about 10, and the saturation solubility of CaCO 3 is lowered to facilitate precipitation.
- the water treatment system is in a condition (specifically about pH 7) where CaCO 3 is difficult to precipitate. Therefore, when recovering CaCO 3 , a neutralization section (not shown) is provided on the downstream side of the second precipitation apparatus 301b, and the pH of the supernatant discharged from the second precipitation apparatus 301b in the neutralization section is 7 It is preferable to feed to a desalting part or an ion selective removal part after adjusting to a grade.
- a separation unit is provided as in the third to sixth embodiments, and the scale component ions can be recovered as a solid. . Further, by using the same arrangement as in the fifth and sixth embodiments, the concentration of scale component ions other than Ca 2+ and CO 3 2 ⁇ can be reduced. However, CaSO 4 has low solubility in water. When the separation unit mainly recovers CaSO 4 , the second precipitation device is unnecessary, and the supernatant of the first precipitation device may be circulated upstream of the desalination unit or the ion selective removal unit. good.
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Abstract
Description
この場合、前記イオン選択性除去部で分離された前記2価以上のイオンを含む多価イオン濃縮水が、前記イオン選択性除去部から排出されて前記脱塩部の上流側に供給されることが好ましい。
この場合、前記脱塩処理で前記脱塩部から排出された処理水が、前記イオン選択性除去部の上流側に供給されることがより好ましい。
上記水処理システムにおけるイオン選択性除去部は、具体的にイオン選択性を有するナノフィルタである。本発明者らは、イオンの種類によりナノフィルタによる除去率が異なり、スケール成分となる2価以上のイオン(アルカリ土類金属イオン、Mg2+、SO4 2-など)の除去率を極めて高くできることに着目した。
脱塩部は、脱塩及び再生が交互に繰り返されるため、電極及びイオン交換膜でスケールが発生しにくい。一方で、除去イオンの価数選択性がなく、被処理水中の全てのイオンが除去される。また、処理に多大な電力を要するので、運転コストが高い。
そこで、脱塩部及びイオン選択性除去部のいずれが上流側に設置されるかは、脱塩部及びイオン選択性除去部のそれぞれの利点・欠点と、被処理水の水質とに応じて決定される。
特に、イオン選択性除去部から排出された多価イオン濃縮水を脱塩部に循環させる構成とすると、2価以上のイオンの除去率を更に高めることが可能となる。
特に、脱塩部の処理水をイオン選択性除去部に循環させる構成とすると、イオン除去率を更に高めることができるとともに、水処理システムの水回収率をさらに高めることができる。
前記イオン濃縮部は、脱塩装置、冷却塔及びボイラの少なくとも一つを含む。
該分離部が、前記濃縮水中の前記2価以上のイオンを固体として析出させて沈殿させる沈殿部と、該沈殿部から排出された前記固体を含む水から前記固体を分離する脱水部とを備え、
前記沈殿部中の上澄液が、前記脱塩部の上流側または前記イオン選択性除去部の上流側に供給される構成としても良い。
さらに、本発明の水処理システムは従来の装置と比べて小型化が可能であるという効果も奏する。
図1は、本発明の第1実施形態に係る水処理システムの概略図である。第1実施形態の水処理システム1は、被処理水の上流側から順に、脱塩部10及びイオン選択性除去部20を備える。
上記イオンのうち、少なくとも2価の金属イオンであるアルカリ土類イオンやMg2+が除去されればスケール発生は防止できる。従って、水処理システム1において2価以上のイオンの除去率を高めれば、F-やHCO3 -などの1価のスケール成分イオンが残留したとしても、スケール析出を防止できる。
具体的に、イオン選択性除去部20は、イオン選択性を有するナノフィルタを備える装置である。ナノフィルタを挟んで上流側が濃縮部であり、下流側が処理部である。ナノフィルタは、1~2nm程度の孔を多数有するフィルタである。本実施形態で使用できるナノフィルタの2価以上のイオンの除去率(分離率)は、80%以上、望ましくは98%以上、さらに望ましくは99.8%以上であり、1価イオンなどその他のイオンの除去率は45~80%である。
上述した性状の被処理水が脱塩部10に流入する。脱塩部10は、以下の脱塩工程及び再生工程を実施する。
脱塩部10の電極11がプラスに、電極13がマイナスになるように、各電極11,13に電圧が印加される。上記の通電状態を「正」と称する。この時、バルブV1が開放され、バルブV2が閉鎖される。
脱塩工程が所定時間実施された後、電極11がマイナスに、電極13がプラスになるように、各電極11,13に電圧が印加される。すなわち、電極は「逆」の通電状態となる。電極11,13が逆の通電状態となるのと同時に、バルブV1が閉鎖されバルブV2が開放される。これにより、再生工程が開始される。
所定時間経過後、図1及び図2に図示されない系統から清浄な水(清水)が供給される。流路15に放出されたイオンは清水とともに脱塩部10から排出される。脱塩部10から排出された水は、濃縮水として濃縮水排出路18を通過して水処理システム1の系外へ排出される。
脱塩部10から排出された処理水がイオン選択性除去部20に流入する。脱塩部の処理水中に含まれるイオンのうち分離率に対応する量が、ナノフィルタを透過することができずに濃縮部に残留し、100%-分離率に対応する量が処理部側に透過する。従って、Na+やCl-などの1価イオンの一部は、イオン選択性除去部を透過する。一方、2価以上のイオンは、イオン選択性除去部により98%以上除去され、濃縮部内の高濃度に2価以上のイオンを含む水(多価イオン濃縮水)と、下流側の処理部内の2価以上のイオンの大部分が除去された(2価以上のイオンの濃度が2%以下に低減された)水とに分離される。
循環部が設置されない場合、多価イオン濃縮水は多価イオン濃縮水排出部22から水処理システム1の系外に排出される。
L1-1:脱塩部入口配管(循環部接続位置の下流側)
L1-2:処理水排出路
L1-3:濃縮水排出路
L1-4:循環部配管
L1-5:除去水排出部配管
シミュレーションは、以下の条件で行った。
脱塩部:水回収率80%、イオン除去率80%。
イオン選択性除去部:水回収率85%、2価以上のイオン除去率98%。1価イオン除去率60%。
このように、被処理水が2価以上のイオンを含んで構成されるスケール成分が飽和溶解度付近若しくは飽和溶解度よりも高い水質の場合、第1実施形態の構成の水再生処理システムで水処理を行うと、2価以上のイオン濃度を極めて低くすることができるので、スケール析出抑制に有利である。
水中に存在するシリカの溶解度はpHに依存し変化し、pHが9以上でイオン状のシリカとして水中に著しく溶解する。pH調整部50は、イオン選択性除去部20とイオン濃縮部40との間を通過する水のpH(図3において不図示のpHで計測される)が9以上となるように、水中にアルカリ剤を投入する。ここで、アルカリ剤は、Na、Kなどのアルカリ金属の水酸化物の水溶液である。
図3及び図4は、本発明の第2実施形態に係る水処理システムの概略図である。
第2実施形態では、2価以上のイオンを含んで構成されるスケール成分が飽和溶解度付近、若しくは、飽和溶解度より低い水が処理対象となる。例えば、河川水、下水処理水、かん水、工場排水、工場排水処理水などである。
下水処理水や工場排水処理水は、有機物や有害物質等を除去した後の水である。有機物や有害物質等を除去するために、水処理システムの上流側に前処理部、及び、有機物処理部が設置されても良い。前処理部において、被処理水中の油分、重金属類、浮遊粒子などが被処理水から除去される。有機物処理部は、微生物を用いて有機物を分解除去する生物処理部と、有機物を化学的に酸化処理する化学酸化処理部と、活性炭と、紫外線処理装置とが、適宜組み合わされた構成とされる。
被処理水の水質に応じ、図3あるいは図4の構成を選択する。被処理水中の2価以上のイオン濃度が非常に低く、脱塩部110の処理水中の2価以上のイオン濃度が十分に低減されている場合は、図4のように循環部を設けなくても良い。
被処理水がイオン選択性除去部120に流入する。第1実施形態と同様に、イオン選択性除去部120が、被処理水を多価イオン濃縮水と、2価以上のイオン濃度が低減された水とに分離する。
2価以上のイオン濃度が低減された水は、除去水排出部121を通じてイオン選択性除去部120から排出される。排出された水は、イオン濃縮部140に送給される。
多価イオン濃縮水は、多価イオン濃縮水排出部122を通じてイオン選択性除去部120から排出され、脱塩部110に送給される。
脱塩部110は第1実施形態と同様の脱塩工程及び再生工程を実施し、多価イオン濃縮水を処理する。第2実施形態では、脱塩工程で多価イオン濃縮水中の2価以上のイオンを吸着・除去する。
再生工程により生成する濃縮水は、濃縮水排出路118を通じて図3の水処理システム101または図4の水処理システム201の系外に排出される。
L2-1:イオン選択性除去部入口配管(循環部接続位置の下流側)
L2-2:脱塩部入口配管(多価イオン濃縮水排出部に接続)
L2-3:濃縮水排出路
L2-4:循環部配管(処理水排出路に接続)
L2-5:イオン選択性除去部の除去水排出部配管
シミュレーションは、以下の条件で行った。
脱塩部:水回収率80%、イオン除去率80%。
イオン選択性除去部:水回収率85%、2価以上のイオン除去率98%。1価イオン除去率60%。
実施例2の被処理水よりも2価以上のイオン濃度が低い水を処理する場合には、L2-4での処理水中の2価以上のイオン濃度が表3よりも更に低減することになる。従って、脱塩部の処理水の水質(表3のL2-4に相当)がイオン選択性除去部の除去水の水質(表3のL2-5に相当)と同程度になる場合は、図4のように循環部を設けなくても良い。
脱塩装置として逆浸透膜装置を採用した場合は、逆浸透膜装置の下流側に、蒸発器や晶析器が設置されても良い。
図5は、本発明の第3実施形態として、第1実施形態の水処理システムにおける脱塩部の濃縮水からCaを固体として分離回収する構成を説明する概略図である。
水処理システム1の濃縮水排出路18は、分離部300に接続する。分離部300は、沈殿部301及び脱水部302を備える。図5は、図1の水処理システムにおいて、Ca2+及びCO3 2-を主たるスケール成分イオンとして含む濃縮水からCaCO3を回収する場合を例示する。
図6は、本発明の第4実施形態として、第2実施形態の水処理システムにおける脱塩部の濃縮水からCaを固体として分離回収する構成を説明する概略図である。図6は、図3の水処理システムにおいて、Ca2+及びCO3 2-を主たるスケール成分イオンとして含む濃縮水からCaCO3を回収する場合を例示する。図6において、図5と同じ構成には同じ符号を付している。
分離部400の構成は第3実施形態と同じである。図6においては、第2沈殿装置301bの上澄液が、イオン選択性除去部120の上流側に循環される構成となっている。なお、第2沈殿装置301bがイオン選択性除去部120と脱塩部110との間の配管に接続され、第2沈殿装置301bの上澄液が脱塩部110に循環されても良い。上澄液の供給先は、上澄液の性状、被処理水の性状、及び、イオン選択性除去部120の多価イオン濃縮水の性状に応じて、適宜選択することができる。
図7は、本発明の第5実施形態として、第1実施形態の水処理システムの上流に分離部を設置する構成を説明する概略図である。図7は、図1の水処理システムに接続される構成であり、被処理水中のスケール成分イオンが主としてCa2+及びCO3 2-である場合の例である。図7において、図5と同じ構成には同じ符号を付している。
図7では、循環部30は第2沈殿装置301bと脱塩部10との間の配管に接続され、イオン選択性除去部20の多価イオン濃縮水が上澄液とともに脱塩部10に送給されている。ただし、多価イオン濃縮水の性状、被処理水の性状、及び、上澄液の性状に応じて、循環部30は第1沈殿装置301aに接続されて、多価イオン濃縮水が第1沈殿装置301aに供給される構成としても良い。
<第6実施形態>
図8は、本発明の第6実施形態として、第2実施形態の水処理システムの上流に分離部を設置する構成を説明する概略図である。図8は、図3の水処理システムに接続される構成であり、被処理水中のスケール成分イオンが主としてCa2+及びCO3 2-である場合の例である。図8において、図5と同じ構成には同じ符号を付している。
なお、第6実施形態は、図4の水処理システムに分離部を設置した構成としても良い。
図8では、濃縮水排出路118は第1沈殿装置301aに接続され、脱塩部110の濃縮水が第1沈殿装置301aに送給されている。ただし、濃縮水の性状、被処理水の性状、及び、上澄液の性状に応じて、濃縮水排出路118は第2沈殿装置301bとイオン選択性除去部120との間の配管に接続されて、濃縮水がイオン選択性除去部120に供給される構成としても良い。
但し、CaSO4は水に対する溶解度が小さい。分離部が主にCaSO4を回収する場合は、第2沈殿装置が不要であり、第1沈殿装置の上澄液が脱塩部またはイオン選択性除去部の上流側に循環される構成としても良い。
10,110 脱塩部
11,13 電極
12 陰イオン交換膜
14 陽イオン交換膜
15 流路
16 排出路
17,117 処理水排出路
18,118 濃縮水排出路
20,120 イオン選択性除去部
21,121 除去水排出部
22,122 多価イオン濃縮水排出部
30,130 循環部
40,140 イオン濃縮部
50,150 pH調整部
300,400,500,600 分離部
301 沈殿部
301a 第1沈殿装置
301b 第2沈殿装置
302 脱水部
Claims (10)
- 互いに逆極性に帯電される一対の対向する電極、該電極の間に位置しイオンを含む水が流通可能とされる流路、及び、各々の前記電極の前記流路側に設置されるイオン交換膜を含み、前記電極に前記イオンを吸着させて前記イオンを含む水を脱塩処理する脱塩処理と前記電極から前記イオンを脱離させる再生処理とを行う脱塩部と、
前記脱塩部の下流側または上流側に設けられ、前記イオンの内スケール成分となる2価以上のイオンの除去率が、1価イオンの前記イオンの除去率よりも相対的に高く、前記イオンを含む水から前記2価以上のイオンを分離し除去するイオン選択性除去部とを備える水処理システム。 - 前記イオン選択性除去部が前記脱塩部の下流側に設けられ、前記イオン選択性除去部が、前記脱塩部で前記脱塩処理された後の処理水から前記2価以上のイオンを除去する請求項1に記載の水処理システム。
- 前記イオン選択性除去部で分離された前記2価以上のイオンを含む多価イオン濃縮水が、前記イオン選択性除去部から排出されて前記脱塩部の上流側に供給される請求項2に記載の水処理システム。
- 前記イオン選択性除去部が前記脱塩部の上流側に設けられ、
前記脱塩部が、前記イオン選択性除去部で分離された前記2価以上のイオンを含む多価イオン濃縮水を受け入れ、前記多価イオン濃縮水を脱塩処理する請求項1に記載の水処理システム。 - 前記脱塩処理で前記脱塩部から排出された処理水が、前記イオン選択性除去部の上流側に供給される請求項4に記載の水処理システム。
- 前記脱塩部及び前記イオン選択性除去部の下流側に、前記処理水及び前記イオン選択性除去部で前記2価以上のイオンが除去された後の水を受け入れ、前記受け入れた水中の前記イオンを濃縮するイオン濃縮部が設置される請求項1乃至請求項5に記載の水処理システム。
- 前記イオン濃縮部が、脱塩装置、冷却塔及びボイラの少なくとも一つを含む請求項6に記載の水処理システム。
- 前記脱塩部及び前記イオン選択性除去部の下流側であって前記イオン濃縮部の上流側に、前記2価以上のイオンが除去された後の水中にアルカリ金属水酸化物を投入して前記2価以上のイオンが除去された後の水のpHを調整するpH調整部が設置される請求項6または請求項7に記載の水処理システム。
- 前記脱塩部が、前記再生処理で前記脱塩部から排出された濃縮水を受け入れる分離部と接続し、
該分離部が、前記濃縮水中の前記2価以上のイオンを固体として析出させて沈殿させる沈殿部と、該沈殿部から排出された前記固体を含む水から前記固体を分離する脱水部とを備え、
前記沈殿部中の上澄液が、前記脱塩部の上流側または前記イオン選択性除去部の上流側に供給される請求項1乃至請求項8のいずれかに記載の水処理システム。 - 前記脱塩部の上流側に、前記イオンを含む水中の前記2価以上のイオンを固体として析出させて沈殿させる沈殿部と、該沈殿部から排出された前記固体を含む水から前記固体を分離する脱水部とを備える分離部が設置され、
前記沈殿部から排出された上澄液が、前記脱塩部または前記イオン選択性除去部に送給されて脱塩処理される請求項1乃至請求項8のいずれかに記載の水処理システム。
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JP2015512242A JP6189422B2 (ja) | 2013-04-18 | 2013-04-18 | 水処理システム |
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