WO2011108589A1 - Méthode de lavage d'un module à membrane poreuse et appareil de production d'eau douce - Google Patents
Méthode de lavage d'un module à membrane poreuse et appareil de production d'eau douce Download PDFInfo
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- WO2011108589A1 WO2011108589A1 PCT/JP2011/054771 JP2011054771W WO2011108589A1 WO 2011108589 A1 WO2011108589 A1 WO 2011108589A1 JP 2011054771 W JP2011054771 W JP 2011054771W WO 2011108589 A1 WO2011108589 A1 WO 2011108589A1
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- Prior art keywords
- membrane module
- porous membrane
- water
- cleaning
- membrane
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- 238000000034 method Methods 0.000 title claims abstract description 48
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 150
- 239000007800 oxidant agent Substances 0.000 claims abstract description 64
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 42
- 238000001914 filtration Methods 0.000 claims description 59
- 238000004140 cleaning Methods 0.000 claims description 50
- 239000000706 filtrate Substances 0.000 claims description 35
- 230000001590 oxidative effect Effects 0.000 claims description 32
- 238000003860 storage Methods 0.000 claims description 20
- 238000005374 membrane filtration Methods 0.000 claims description 17
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- 230000004907 flux Effects 0.000 description 9
- 239000011148 porous material Substances 0.000 description 8
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 7
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 description 7
- 239000000460 chlorine Substances 0.000 description 7
- 229910052801 chlorine Inorganic materials 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 description 7
- 239000005708 Sodium hypochlorite Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000001223 reverse osmosis Methods 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 6
- 238000000108 ultra-filtration Methods 0.000 description 6
- 238000010612 desalination reaction Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000001471 micro-filtration Methods 0.000 description 5
- 229920002647 polyamide Polymers 0.000 description 5
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- 239000010410 layer Substances 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 244000005700 microbiome Species 0.000 description 3
- 238000001728 nano-filtration Methods 0.000 description 3
- -1 polyethylene Polymers 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000013535 sea water Substances 0.000 description 3
- 239000002351 wastewater Substances 0.000 description 3
- BQCIDUSAKPWEOX-UHFFFAOYSA-N 1,1-Difluoroethene Chemical compound FC(F)=C BQCIDUSAKPWEOX-UHFFFAOYSA-N 0.000 description 2
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- 239000012267 brine Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 229920001577 copolymer Polymers 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 239000002346 layers by function Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000008239 natural water Substances 0.000 description 2
- 230000003472 neutralizing effect Effects 0.000 description 2
- 239000005416 organic matter Substances 0.000 description 2
- 238000010525 oxidative degradation reaction Methods 0.000 description 2
- 229920002239 polyacrylonitrile Polymers 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 102000004169 proteins and genes Human genes 0.000 description 2
- 108090000623 proteins and genes Proteins 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 2
- 235000019345 sodium thiosulphate Nutrition 0.000 description 2
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 1
- QDHHCQZDFGDHMP-UHFFFAOYSA-N Chloramine Chemical compound ClN QDHHCQZDFGDHMP-UHFFFAOYSA-N 0.000 description 1
- 229920001780 ECTFE Polymers 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 239000004695 Polyether sulfone Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 1
- 235000010323 ascorbic acid Nutrition 0.000 description 1
- 229960005070 ascorbic acid Drugs 0.000 description 1
- 239000011668 ascorbic acid Substances 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000009295 crossflow filtration Methods 0.000 description 1
- 238000011033 desalting Methods 0.000 description 1
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- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000003204 osmotic effect Effects 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 229920002493 poly(chlorotrifluoroethylene) Polymers 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 239000005023 polychlorotrifluoroethylene (PCTFE) polymer Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920006393 polyether sulfone Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
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- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
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- 238000011085 pressure filtration Methods 0.000 description 1
- 238000009287 sand filtration Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- UKLNMMHNWFDKNT-UHFFFAOYSA-M sodium chlorite Chemical compound [Na+].[O-]Cl=O UKLNMMHNWFDKNT-UHFFFAOYSA-M 0.000 description 1
- 229960002218 sodium chlorite Drugs 0.000 description 1
- 229940079827 sodium hydrogen sulfite Drugs 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000008400 supply water Substances 0.000 description 1
- 229910021642 ultra pure water Inorganic materials 0.000 description 1
- 239000012498 ultrapure water Substances 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Images
Classifications
-
- 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
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
-
- 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
- B01D2321/04—Backflushing
-
- 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
- B01D2321/16—Use of chemical agents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/02—Details relating to pores or porosity of the membranes
- B01D2325/0283—Pore size
-
- 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
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- 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
- C02F1/70—Treatment of water, waste water, or sewage by reduction
-
- 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
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/14—Maintenance of water treatment installations
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/16—Regeneration of sorbents, filters
Definitions
- the present invention relates to a method for cleaning a porous membrane module and a fresh water generator in a fresh water generator that obtains water by membrane filtration of raw water with a porous membrane.
- a semipermeable membrane module provided with (hereinafter collectively referred to as a semipermeable membrane) is frequently used.
- pretreatment means such as sand filtration, activated carbon filtration, MF membrane filtration, UF membrane filtration are provided in front of the semipermeable membrane module to prevent clogging of the semipermeable membrane and prolong the membrane life.
- MF membranes and UF membranes that reliably capture and remove turbid substances and microorganisms are preferably used.
- Patent Document 1 proposes a method of adding sodium hypochlorite to the counter pressure cleaning water
- Patent Document 2 proposes using ozone-containing water for the counter pressure cleaning water.
- the oxidizing agent has an effect of decomposing and removing organic substances such as humic substances and microorganism-derived proteins adhering to the membrane surface and membrane pores.
- the membrane filtration water immediately after the start of filtration is highly charged. Concentration of oxidant is often included.
- Semipermeable membranes, especially polyamide-based semipermeable membranes are prone to oxidative degradation due to oxidizers, so the membrane module and the secondary pipe on the filtration side can be washed thoroughly with raw water or membrane filtered water, It is necessary to add a reducing agent such as sodium thiosulfate or sodium bisulfite to reduce and neutralize the oxidizing agent.
- Patent Document 5 proposes a method of performing back pressure cleaning with a reducing agent after back pressure cleaning with an oxidizing agent. However, since backwashing is frequently used, the water recovery rate and the amount of produced water are reduced.
- Japanese Unexamined Patent Publication No. 2001-79366 Japanese Unexamined Patent Publication No. 2001-187324 Japanese Unexamined Patent Publication No. 2006-305444 Japanese Unexamined Patent Publication No. 2008-29906 Japanese Patent No. 3380114
- a membrane separation apparatus for membrane filtration of raw water with a porous membrane module
- a method for preventing the leakage of an oxidant to the subsequent stage having a high water recovery rate and a high production water volume, and effectively washing the porous membrane module, and fresh water
- a method for preventing the leakage of an oxidant to the subsequent stage having a high water recovery rate and a high production water volume, and effectively washing the porous membrane module, and fresh water
- the present invention relates to the following (1) to (12).
- (1) A method for cleaning a porous membrane module comprising performing back pressure cleaning using water containing an oxidizing agent and then filtering water containing a reducing agent through the porous membrane module.
- (2) The method for cleaning a porous membrane module according to (1) comprising discharging at least a part of the membrane filtrate of water containing a reducing agent from a bypass line provided in the back pressure cleaning line.
- (3) The method according to (1) or (2) including feeding at least a part of the membrane filtrate of the water containing the reducing agent from the bypass line provided in the back pressure washing line to the membrane filtrate storage tank. Cleaning method for porous membrane module.
- the method for cleaning a porous membrane module according to any one of (1) to (5) comprising: (7) The porous material according to any one of (1) to (6), comprising filtering at least part of the membrane filtrate obtained by filtration using a porous membrane module with a semipermeable membrane. Membrane module cleaning method.
- a porous membrane module a porous membrane module; A counter pressure washing unit for supplying membrane filtration water of the porous membrane module from the secondary side to the primary side of the porous membrane module; An oxidizing agent supply unit that supplies an oxidizing agent to a line that supplies the membrane filtrate of the porous membrane module from the secondary side to the primary side of the porous membrane module; A reducing agent supply unit for supplying a reducing agent to the primary side of the porous membrane module; Including fresh water generator. (9) The fresh water generator according to (8), including a bypass line connected to a line for supplying membrane filtrate from the secondary side to the primary side of the porous membrane module and an out-of-system discharge line.
- the membrane module cleaning method of the present invention in a membrane separation apparatus for membrane filtration of raw water with a porous membrane module, leakage of an oxidant to the subsequent stage is prevented, water recovery rate and production water volume are high, and effectively A method for cleaning a porous membrane module can be provided.
- FIG. 1 is a schematic flow diagram of a fresh water generator to which the present invention is applied.
- FIG. 1 An embodiment of the present invention will be described below with reference to FIG. 1, taking as an example the case of membrane filtration using a pressure-type hollow fiber membrane module (hereinafter referred to as hollow fiber membrane module) filtration device provided with a porous membrane. .
- hollow fiber membrane module a pressure-type hollow fiber membrane module
- the present invention is not limited to the embodiment described below.
- a fresh water generator to which the cleaning method of the present invention can be applied is, for example, as shown in FIG. 1, a raw water storage tank 1 for storing raw water, a raw water supply pump 2 for supplying raw water, and opened when raw water is supplied.
- a membrane filtrate storage tank 7 for storing filtrate
- a semipermeable membrane module 8 a booster pump 9 for supplying hollow fiber membrane filtrate to the semipermeable membrane module 8, and a hollow fiber by supplying hollow fiber membrane filtrate.
- Drain valve 12 and compressed air are used as primary for hollow fiber membrane module 4 Oxidized into an air supply unit including an air flush valve 13 and a compressor 14 which is a supply source of compressed air, an oxidant storage tank 15 for storing an oxidant, and back-pressure wash water.
- An oxidant supply unit including an oxidant supply pump 16 for supplying the oxidant, a reductant storage tank 17 for storing the reductant, a reducing agent supply unit including a reductant supply pump 18 for supplying the reductant to raw water, and an oxidant
- the air supply unit may include a blower.
- raw water stored in the raw water storage tank 1 with the raw water supply valve 3 open is supplied to the primary side of the hollow fiber membrane module 4 by the raw water supply pump 2.
- the filtration of the hollow fiber membrane module 4 is performed by opening the filtration valve 6.
- the filtration time is preferably set as appropriate according to the raw water quality and the filtration flux, but the filtration may be continued until a predetermined filtration differential pressure is reached.
- the membrane filtrate of the hollow fiber membrane module 4 was temporarily stored in the membrane filtrate storage tank 7, then pressurized by the booster pump 9, supplied to the semipermeable membrane module 8, and solutes such as salt were removed. Membrane filtrate and solutes such as salt are separated into concentrated water.
- the hollow fiber membrane module 4 is periodically subjected to back pressure washing in which washing water is caused to flow backward from the direction opposite to the filtration direction. Since this cleaning is performed while the semipermeable membrane module 8 continues to operate, the semipermeable membrane module 8 uses the filtrate stored in the membrane filtrate storage tank 7 during this period.
- the raw water supply pump 2 is stopped, the raw water supply valve 3 and the filtration valve 6 are closed, and the filtration process of the hollow fiber membrane module 4 is stopped. Then, the air vent valve 5 and the backwash valve 11 are opened, and backwashing is performed. This is done by operating the pump 10.
- the cleaning water is water containing an oxidizing agent
- the oxidizing agent in the oxidizing agent storage tank 15 is supplied by the oxidizing agent supply pump 16.
- the back-pressure washing of the hollow fiber membrane module is performed regularly while continuing the membrane filtration, and the frequency is usually about once every 15 to 120 minutes. Further, the back pressure cleaning using the cleaning water containing the oxidant may be applied to the back pressure cleaning every time, but the chemical cost is reduced and the risk of the oxidant leaking to the semipermeable membrane module 8 at the subsequent stage is reduced. For the reason, it is preferable to carry out the treatment at a frequency of several times a day to once a week.
- the time for the two types of backwashing described above is not particularly limited, but is preferably within the range of 5 to 120 seconds. If the back pressure washing time for one time is less than 5 seconds, a sufficient washing effect cannot be obtained, and if it exceeds 120 seconds, the operation efficiency of the hollow fiber membrane module is lowered.
- the flux at the time of back pressure washing is not particularly limited, but is preferably 0.5 times or more of the filtration flux. If the back-pressure washing flux is less than 0.5 times the filtration flux, it is difficult to sufficiently remove the organic pollutant adhered and deposited on the membrane surface. A higher back-pressure cleaning flux is preferable because the membrane cleaning effect is higher, but it is appropriately set within a range that does not cause damage to the membrane module container or membrane cracks.
- the concentration of the oxidizing agent may be in the range of several mg / L to several thousand mg / L in the case of sodium hypochlorite, but 50 mg / L when the hollow fiber membrane module 4 is held with washing water containing the oxidizing agent. L to about 1000 mg / L is preferable. This is because if the oxidant concentration is too low, the hollow fiber membrane module 4 is completely consumed while being held in the wash water containing the oxidant, and a sufficient cleaning effect cannot be obtained. This is because the cost of treating wastewater is high.
- the holding time in the hollow fiber membrane module 4 with the washing water containing the oxidizing agent is preferably about 5 to 180 minutes, and more preferably about 10 to 30 minutes. This is because if the contact time is too short, the cleaning power is weak, and if it is too long, the apparatus is stopped for a long time, and the operation efficiency of the apparatus is lowered.
- the air washing valve 13 is opened and the compressed air of the compressor 14 is sent to the primary side of the hollow fiber membrane module 4 to vibrate the membrane.
- the air cleaning is preferably performed during the two types of back pressure cleaning described above, before or after the execution, or at least a part of the time held in the hollow fiber membrane filtered water containing the oxidizing agent in the hollow fiber membrane module 4. .
- Water pushed out to the primary side of the hollow fiber membrane module 4 and air supplied to the primary side of the hollow fiber membrane module 4 are discharged out of the system through the air vent valve 5.
- the pressure of the compressed air is higher because the cleaning effect of the membrane is higher, but it is appropriately set within a range in which the membrane is not damaged.
- natural water to which the reducing agent was added with a membrane module is implemented.
- the air washing valve 13 was closed, and the drain valve 12 was opened, so that it was detached from the membrane surface and pores and floated in the hollow fiber membrane module 4.
- a drainage process in which fouling substances are discharged out of the system is performed.
- the drainage valve 12 After completion of the drainage process, the drainage valve 12 is closed, the raw water supply valve 3 is opened, the raw water supply pump 2 and the reducing agent supply pump 18 are operated to perform the water supply process, and the primary side of the hollow fiber membrane module 4 is filled with water. After that, the air vent valve 5 is closed and the bypass valve 20 is opened, and filtration is performed while discharging from the bypass line 19 to the outside of the system. After filtering for a certain time, the reducing agent supply pump 18 is stopped, the filtration valve 6 is opened, and the backwash valve 11 and the bypass valve 20 are closed, so that the process returns to the filtration process and the above-described process is repeated.
- the reducing agent used for neutralizing the oxidizing agent inorganic reducing agents such as sodium hydrogen sulfite, sodium sulfite, and sodium thiosulfate can be used.
- Organic reducing agents such as oxalic acid and ascorbic acid are not suitable for the present invention due to the problem of increasing the wastewater TOC concentration and increasing the cost of wastewater treatment.
- the concentration of the reducing agent may be in the range of several mg / L to several thousand mg / L, and is necessary for reducing and neutralizing the oxidizing agent remaining in the hollow fiber membrane module 4 and the secondary pipe on the filtration side. More preferably, the concentration is about 1 to 5 times the theoretical concentration.
- the water to which the oxidant is added may be the membrane filtered water of the hollow fiber membrane module 4, the membrane filtered water of the semipermeable membrane module 8, or the concentrated water.
- the rate is lowered and concentrated water is used, the oxidant is consumed by the concentrated organic matter. Therefore, it is preferable to use the membrane filtered water of the hollow fiber membrane module 4.
- the membrane filtrate containing the reducing agent may be sent to the membrane filtrate storage tank 7 without passing through the bypass line 19, but the reduction neutralization is insufficient or the backwash valve 11. Since a small amount of oxidant remaining between the oxidant supply pump 16 and the oxidant supply pump 16 may leak into the secondary pipe of the hollow fiber membrane module 4 at the time of the next back pressure washing, It is preferable to pass all of the water.
- bypass line 19 may be provided in the backwash pump 10 and the membrane filtrate storage tank 7. I do not care.
- the bypass line 19 may be connected to the membrane filtrate storage tank 7, but may be connected to an out-of-system discharge line in order to reduce the risk of leakage of an oxidizing agent that is insufficiently reduced and neutralized. preferable.
- the water to which the reducing agent is added may be raw water, membrane filtered water of the hollow fiber membrane module 4, membrane filtered water of the semipermeable membrane module 8, or concentrated water, but the membrane of the hollow fiber membrane module 4 or the semipermeable membrane module 8 may be used.
- filtered water the water recovery rate is lowered, and when concentrated water of the semipermeable membrane module 8 is used, there is a concern about clogging with concentrated organic substances and inorganic substances, and therefore, raw water is preferably used.
- the time for filtering the water containing the reducing agent is preferably performed until the oxidizing agent in the hollow fiber membrane module 4 or the secondary side pipe of the hollow fiber membrane module 4 is reduced and neutralized.
- the concentration of free chlorine in the bypass line 19 is about 0.1 m / L.
- a method for measuring the free chlorine concentration a DPD method, a current method, an absorptiometric method, or the like is used.
- water is collected as appropriate, and the free chlorine concentration is measured by the DPD method and the current method, or the free chlorine concentration is measured by a continuous automatic measuring instrument using the absorptiometry. By these measurements, it is preferable to monitor the free chlorine concentration and determine and adjust the time for filtering the water to which the reducing agent has been added.
- any of the immersion membrane modules that are immersed in a membrane immersion tank containing raw water and suction filtered with a pump, siphon or the like can be used. I do not care.
- a pressurizing membrane module an external pressure type or an internal pressure type may be used, but an external pressure type is preferred from the viewpoint of simplicity of pretreatment.
- the material of the porous membrane constituting the module is not particularly limited as long as it is a porous hollow fiber membrane, but is not limited to inorganic materials such as ceramics, polyethylene, polypropylene, polyacrylonitrile, ethylene-tetrafluoroethylene copolymer, polychloro Trifluoroethylene, polytetrafluoroethylene, polyvinyl fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, chlorotrifluoroethylene-ethylene copolymer, polyvinylidene fluoride, It is preferable to contain at least one selected from the group consisting of polysulfone, cellulose acetate, polyvinyl alcohol, polyethersulfone, and vinyl chloride, and in terms of film strength and chemical resistance, More preferably vinylidene fluoride (PVDF), polyacrylonitrile is more preferable from the viewpoint that
- the shape of the separation membrane is not particularly limited, and may be a hollow fiber membrane, a flat membrane, a tubular membrane, a monolith membrane, or the like.
- the filtration method may be either a full-volume filtration method or a cross-flow filtration method, but a full-volume filtration is preferred from the viewpoint of low energy consumption.
- the filtration flow rate control method of the membrane filtration device may be constant flow filtration or constant pressure filtration, but it is constant flow filtration from the viewpoint of easy control of the production water quantity of filtrate water. Is preferred.
- the semipermeable membrane is a membrane having a semipermeable property that allows some components in the mixed liquid to be separated, for example, a solvent to permeate but not other components, and includes a nanofiltration membrane and a reverse osmosis membrane.
- the material polymer materials such as cellulose acetate polymer, polyamide, polyester, polyimide, vinyl polymer are often used.
- the membrane structure has a dense layer on at least one side of the membrane, an asymmetric membrane having fine pores gradually increasing from the dense layer to the inside of the membrane or the other side, and another layer on the dense layer of the asymmetric membrane.
- a composite membrane having a very thin separation functional layer formed of a material can be used as appropriate.
- the membrane form includes a hollow fiber membrane and a flat membrane.
- the present invention can be carried out regardless of the film material, film structure and film form, and any of them is effective, but as typical films, for example, cellulose acetate-based or polyamide-based asymmetric membranes and polyamide-based, There are composite membranes having a urea-based separation functional layer, and it is preferable to use a cellulose acetate-based asymmetric membrane and a polyamide-based composite membrane from the viewpoint of water production, durability, and salt rejection.
- the operating pressure of the semipermeable membrane module 8 is 0.1 MPa to 15 MPa, and can be properly used depending on the type of supply water, the operation method, and the like. It is used at a relatively low pressure when supplying low osmotic pressure water such as brine or ultrapure water, and at a relatively high pressure when desalinating seawater, treating wastewater, and recovering useful materials.
- the semipermeable membrane module 8 provided with a nanofiltration membrane or a reverse osmosis membrane is of course a module in which one to several pressure permeable membrane elements are housed in a pressure vessel. It also includes those arranged in parallel. Combination, number, and arrangement can be arbitrarily performed according to the purpose.
- the semipermeable membrane element is formed for practical use of the semipermeable membrane, the flat membrane is a spiral, tubular, plate and frame type element, and the hollow fiber membrane is It can be used after being bundled into a case, but the present invention does not depend on the form of these semipermeable membrane elements.
- the hollow fiber membrane module 4 includes a pressure-sensitive membrane module (HFU-2020), which is a hollow fiber UF membrane made of polyvinylidene fluoride having a molecular weight cut off of 150,000 Da manufactured by Toray Industries, Inc. and having a membrane area of 72 m 2.
- HFU-2020 a pressure-sensitive membrane module
- TM820-400 reverse osmosis membrane elements manufactured by Toray Industries, Inc. were used for the semipermeable membrane module 8, and the membrane filtration flow rate was 60 m 3 / d, the concentrated water flow rate was 120 m 3 / d, and the recovery rate was 33%. did.
- the raw water supply valve 3 and the filtration valve 6 are closed and the raw water supply pump 2 is stopped, and at the same time, the backwash valve 11, the air washing valve 13 and the air vent valve 5 are opened.
- the backwash pump 10 was operated, and backwashing with a flux of 3 m / d and air washing for supplying air at 100 L / min from below the membrane module were simultaneously performed for 1 minute. Thereafter, the backwash valve 11 and the air wash valve 13 were closed and the backwash pump 10 was stopped.
- the drain valve 12 was opened to discharge all the water in the hollow fiber membrane module 4 out of the system.
- the raw water supply valve 3 and the filtration valve 6 are opened, the raw water supply pump 2 is operated, the raw water is supplied into the hollow fiber membrane module 4, the air vent valve 5 is closed, and the process returns to the filtration step. The process was repeated.
- back pressure washing using washing water in which sodium hypochlorite in the oxidant storage tank 15 was added to the membrane filtrate of the hollow fiber membrane module 4 was performed four times a day.
- the backwash valve 11, the air wash valve 13, and the air vent valve 5 are opened, the backwash pump 10 and the oxidant supply pump 16 are operated, and the back pressure washing of the flux 3 m / d and the primary of the hollow fiber membrane module 4 are performed.
- Air cleaning was simultaneously performed for 1 minute to supply air at 100 L / min to the side.
- the chlorine concentration in the backwash water at this time was 300 mg / L.
- the backwash pump 10 and the oxidant supply pump 16 were stopped, and the inside of the hollow fiber membrane module 4 was held at a chlorine concentration of 300 mg / L for 20 minutes.
- the drain valve 12 was opened, and all the water in the hollow fiber membrane module 4 was discharged out of the system.
- the raw water supply valve 3 and the bypass valve 20 are opened, the raw water supply pump 2 and the reducing agent supply pump 18 are operated, and the raw water to which sodium bisulfite is added is supplied into the hollow fiber membrane module 4, and then the air
- the drain valve 5 was closed, and filtration was carried out for 1 minute while passing water through the bypass line 19.
- the raw water supply valve 3 is closed, the raw water supply pump 2 and the reducing agent supply pump 18 are stopped, the air vent valve 5 and the drain valve 12 are opened, and all the water in the hollow fiber membrane module 4 is discharged out of the system. did.
- Such a reducing agent rinsing step was performed three times. At this time, the concentration of sodium bisulfite in the raw water was 300 mg / L.
- the reducing agent supply pump 18 was stopped, the filtration valve 6 was opened, the backwash valve 11 and the bypass valve 20 were closed, the process was returned to the filtration step, and the above-described steps were repeated.
- the water recovery rate of the hollow fiber membrane module 4 was 92.7% (product water volume: 162.1 m 3 / day), and the filtration differential pressure was 60-70 kPa for 2 months against 60 kPa immediately after the start of operation. Stable operation was possible. Moreover, the desalination rate of the semipermeable membrane module 8 remained stable at 99.6% immediately after the start of operation, and 99.6% after two months.
- Example 1 was the same as Example 1 except that sodium bisulfite was not added to the raw water after backwashing with wash water to which sodium hypochlorite had been added.
- the water recovery rate of the hollow fiber membrane module 4 was 92.7% (product water volume: 162.1 m 3 / day), and the filtration differential pressure was 60-70 kPa for 2 months against 60 kPa immediately after the start of operation. Stable operation was possible.
- the desalination rate of the reverse osmosis membrane module 8 decreased to 92.3% after two months, compared with 99.7% immediately after the start of operation due to oxidative degradation.
- the water recovery rate and production water volume of the hollow fiber membrane module 4 were the same, but the desalination rate of the semipermeable membrane module 8 was lowered.
- the water recovery rate of the hollow fiber membrane module 4 was 92.6% (product water volume 159.7 m 3 / day), and the filtration differential pressure was 60 to 70 kPa for 2 months with respect to 60 kPa immediately after the start of operation. Stable operation was possible.
- the desalination rate of the reverse osmosis membrane module 8 was stable at 99.6% immediately after the start of operation, and 99.6% after 2 months. Compared to Example 1, the desalination rate of the semipermeable membrane module 8 could be stably operated without decreasing, but the water recovery rate of the hollow fiber membrane module 4 was decreased.
- the membrane module cleaning method of the present invention in a membrane separation apparatus for membrane filtration of raw water with a porous membrane module, leakage of an oxidant to the subsequent stage is prevented, water recovery rate and production water volume are high, and effectively A method for cleaning a porous membrane module can be provided.
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
L'invention concerne un appareil de production d'eau douce et une méthode de lavage d'un module à membrane poreuse consistant à réaliser un lavage à contre-pression à l'aide d'eau contenant un agent oxydant, après quoi de l'eau contenant un agent réducteur est filtrée grâce au module à membrane poreuse.
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JP2011517133A JPWO2011108589A1 (ja) | 2010-03-02 | 2011-03-02 | 多孔質膜モジュールの洗浄方法および造水装置 |
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Cited By (3)
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US9333464B1 (en) | 2014-10-22 | 2016-05-10 | Koch Membrane Systems, Inc. | Membrane module system with bundle enclosures and pulsed aeration and method of operation |
USD779631S1 (en) | 2015-08-10 | 2017-02-21 | Koch Membrane Systems, Inc. | Gasification device |
JP2017100101A (ja) * | 2015-12-04 | 2017-06-08 | 住友電気工業株式会社 | 濾過膜の洗浄方法 |
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Publication number | Priority date | Publication date | Assignee | Title |
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US9333464B1 (en) | 2014-10-22 | 2016-05-10 | Koch Membrane Systems, Inc. | Membrane module system with bundle enclosures and pulsed aeration and method of operation |
US9956530B2 (en) | 2014-10-22 | 2018-05-01 | Koch Membrane Systems, Inc. | Membrane module system with bundle enclosures and pulsed aeration and method of operation |
US10702831B2 (en) | 2014-10-22 | 2020-07-07 | Koch Separation Solutions, Inc. | Membrane module system with bundle enclosures and pulsed aeration and method of operation |
USD779631S1 (en) | 2015-08-10 | 2017-02-21 | Koch Membrane Systems, Inc. | Gasification device |
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JP2017100101A (ja) * | 2015-12-04 | 2017-06-08 | 住友電気工業株式会社 | 濾過膜の洗浄方法 |
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