JP2018122206A - Method for washing reverse osmosis membrane - Google Patents
Method for washing reverse osmosis membrane Download PDFInfo
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- JP2018122206A JP2018122206A JP2017014123A JP2017014123A JP2018122206A JP 2018122206 A JP2018122206 A JP 2018122206A JP 2017014123 A JP2017014123 A JP 2017014123A JP 2017014123 A JP2017014123 A JP 2017014123A JP 2018122206 A JP2018122206 A JP 2018122206A
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- Prior art keywords
- cleaning
- reverse osmosis
- osmosis membrane
- cleaning liquid
- alkaline
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- 239000012528 membrane Substances 0.000 title claims abstract description 143
- 238000001223 reverse osmosis Methods 0.000 title claims abstract description 111
- 238000005406 washing Methods 0.000 title claims abstract description 57
- 238000000034 method Methods 0.000 title claims abstract description 45
- 239000007788 liquid Substances 0.000 claims abstract description 105
- -1 amide compound Chemical class 0.000 claims abstract description 39
- 238000004140 cleaning Methods 0.000 claims description 251
- 239000002738 chelating agent Substances 0.000 claims description 22
- 239000002253 acid Substances 0.000 claims description 19
- 239000004094 surface-active agent Substances 0.000 claims description 14
- 239000003638 chemical reducing agent Substances 0.000 claims description 10
- 229920002647 polyamide Polymers 0.000 claims description 7
- 239000003945 anionic surfactant Substances 0.000 claims description 6
- 150000008430 aromatic amides Chemical class 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 30
- 238000011084 recovery Methods 0.000 abstract description 26
- 239000003795 chemical substances by application Substances 0.000 abstract description 23
- 239000003513 alkali Substances 0.000 abstract description 13
- 238000011282 treatment Methods 0.000 abstract description 12
- 239000013522 chelant Substances 0.000 abstract 2
- 238000007796 conventional method Methods 0.000 abstract 1
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 51
- 230000000694 effects Effects 0.000 description 37
- 239000000243 solution Substances 0.000 description 27
- 239000007864 aqueous solution Substances 0.000 description 17
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 12
- 230000004907 flux Effects 0.000 description 12
- DFPAKSUCGFBDDF-UHFFFAOYSA-N Nicotinamide Chemical compound NC(=O)C1=CC=CN=C1 DFPAKSUCGFBDDF-UHFFFAOYSA-N 0.000 description 10
- 238000011156 evaluation Methods 0.000 description 10
- 239000000126 substance Substances 0.000 description 10
- KXDAEFPNCMNJSK-UHFFFAOYSA-N Benzamide Chemical compound NC(=O)C1=CC=CC=C1 KXDAEFPNCMNJSK-UHFFFAOYSA-N 0.000 description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 238000011033 desalting Methods 0.000 description 7
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 description 7
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 description 7
- 239000002351 wastewater Substances 0.000 description 7
- 238000004065 wastewater treatment Methods 0.000 description 7
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 6
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 6
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 6
- 230000006866 deterioration Effects 0.000 description 6
- 239000006185 dispersion Substances 0.000 description 6
- 238000007654 immersion Methods 0.000 description 6
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- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 5
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 5
- 238000010612 desalination reaction Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
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- 229940083575 sodium dodecyl sulfate Drugs 0.000 description 5
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- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
- 239000004952 Polyamide Substances 0.000 description 3
- 150000001346 alkyl aryl ethers Chemical class 0.000 description 3
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- SZHQPBJEOCHCKM-UHFFFAOYSA-N 2-phosphonobutane-1,2,4-tricarboxylic acid Chemical compound OC(=O)CCC(P(O)(O)=O)(C(O)=O)CC(O)=O SZHQPBJEOCHCKM-UHFFFAOYSA-N 0.000 description 2
- QIKYZXDTTPVVAC-UHFFFAOYSA-N 4-Aminobenzamide Chemical compound NC(=O)C1=CC=C(N)C=C1 QIKYZXDTTPVVAC-UHFFFAOYSA-N 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- RGHNJXZEOKUKBD-SQOUGZDYSA-N D-gluconic acid Chemical compound OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C(O)=O RGHNJXZEOKUKBD-SQOUGZDYSA-N 0.000 description 2
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 2
- ZHNUHDYFZUAESO-UHFFFAOYSA-N Formamide Chemical compound NC=O ZHNUHDYFZUAESO-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- DCXYFEDJOCDNAF-REOHCLBHSA-N L-asparagine Chemical compound OC(=O)[C@@H](N)CC(N)=O DCXYFEDJOCDNAF-REOHCLBHSA-N 0.000 description 2
- QIAFMBKCNZACKA-UHFFFAOYSA-N N-benzoylglycine Chemical compound OC(=O)CNC(=O)C1=CC=CC=C1 QIAFMBKCNZACKA-UHFFFAOYSA-N 0.000 description 2
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 2
- DFPAKSUCGFBDDF-ZQBYOMGUSA-N [14c]-nicotinamide Chemical compound N[14C](=O)C1=CC=CN=C1 DFPAKSUCGFBDDF-ZQBYOMGUSA-N 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 2
- 150000008051 alkyl sulfates Chemical class 0.000 description 2
- 150000001408 amides Chemical class 0.000 description 2
- 150000001412 amines Chemical class 0.000 description 2
- CDQSJQSWAWPGKG-UHFFFAOYSA-N butane-1,1-diol Chemical compound CCCC(O)O CDQSJQSWAWPGKG-UHFFFAOYSA-N 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 2
- 238000007865 diluting Methods 0.000 description 2
- 239000012776 electronic material Substances 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- 150000002170 ethers Chemical class 0.000 description 2
- DEFVIWRASFVYLL-UHFFFAOYSA-N ethylene glycol bis(2-aminoethyl)tetraacetic acid Chemical compound OC(=O)CN(CC(O)=O)CCOCCOCCN(CC(O)=O)CC(O)=O DEFVIWRASFVYLL-UHFFFAOYSA-N 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 150000002576 ketones Chemical class 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- NAYYNDKKHOIIOD-UHFFFAOYSA-N phthalamide Chemical compound NC(=O)C1=CC=CC=C1C(N)=O NAYYNDKKHOIIOD-UHFFFAOYSA-N 0.000 description 2
- 229920001515 polyalkylene glycol Polymers 0.000 description 2
- 229920005862 polyol Polymers 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910021642 ultra pure water Inorganic materials 0.000 description 2
- ZFPGARUNNKGOBB-UHFFFAOYSA-N 1-Ethyl-2-pyrrolidinone Chemical compound CCN1CCCC1=O ZFPGARUNNKGOBB-UHFFFAOYSA-N 0.000 description 1
- AEQDJSLRWYMAQI-UHFFFAOYSA-N 2,3,9,10-tetramethoxy-6,8,13,13a-tetrahydro-5H-isoquinolino[2,1-b]isoquinoline Chemical compound C1CN2CC(C(=C(OC)C=C3)OC)=C3CC2C2=C1C=C(OC)C(OC)=C2 AEQDJSLRWYMAQI-UHFFFAOYSA-N 0.000 description 1
- QHWDUJPWCGEBTH-UHFFFAOYSA-N 4-amino-n-phenylbenzamide Chemical compound C1=CC(N)=CC=C1C(=O)NC1=CC=CC=C1 QHWDUJPWCGEBTH-UHFFFAOYSA-N 0.000 description 1
- 229940126062 Compound A Drugs 0.000 description 1
- RGHNJXZEOKUKBD-UHFFFAOYSA-N D-gluconic acid Natural products OCC(O)C(O)C(O)C(O)C(O)=O RGHNJXZEOKUKBD-UHFFFAOYSA-N 0.000 description 1
- WHUUTDBJXJRKMK-UHFFFAOYSA-N Glutamic acid Natural products OC(=O)C(N)CCC(O)=O WHUUTDBJXJRKMK-UHFFFAOYSA-N 0.000 description 1
- NLDMNSXOCDLTTB-UHFFFAOYSA-N Heterophylliin A Natural products O1C2COC(=O)C3=CC(O)=C(O)C(O)=C3C3=C(O)C(O)=C(O)C=C3C(=O)OC2C(OC(=O)C=2C=C(O)C(O)=C(O)C=2)C(O)C1OC(=O)C1=CC(O)=C(O)C(O)=C1 NLDMNSXOCDLTTB-UHFFFAOYSA-N 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- WHUUTDBJXJRKMK-VKHMYHEASA-N L-glutamic acid Chemical compound OC(=O)[C@@H](N)CCC(O)=O WHUUTDBJXJRKMK-VKHMYHEASA-N 0.000 description 1
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- 229930182816 L-glutamine Natural products 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- ABLZXFCXXLZCGV-UHFFFAOYSA-N Phosphorous acid Chemical compound OP(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 1
- GMZVRMREEHBGGF-UHFFFAOYSA-N Piracetam Chemical compound NC(=O)CN1CCCC1=O GMZVRMREEHBGGF-UHFFFAOYSA-N 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- LEHOTFFKMJEONL-UHFFFAOYSA-N Uric Acid Chemical compound N1C(=O)NC(=O)C2=C1NC(=O)N2 LEHOTFFKMJEONL-UHFFFAOYSA-N 0.000 description 1
- TVWHNULVHGKJHS-UHFFFAOYSA-N Uric acid Natural products N1C(=O)NC(=O)C2NC(=O)NC21 TVWHNULVHGKJHS-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 229960001230 asparagine Drugs 0.000 description 1
- ZVSKZLHKADLHSD-UHFFFAOYSA-N benzanilide Chemical compound C=1C=CC=CC=1C(=O)NC1=CC=CC=C1 ZVSKZLHKADLHSD-UHFFFAOYSA-N 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 229920002301 cellulose acetate Polymers 0.000 description 1
- 239000013043 chemical agent Substances 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 150000003950 cyclic amides Chemical class 0.000 description 1
- 239000011790 ferrous sulphate Substances 0.000 description 1
- 235000003891 ferrous sulphate Nutrition 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000000174 gluconic acid Substances 0.000 description 1
- 235000012208 gluconic acid Nutrition 0.000 description 1
- 235000013922 glutamic acid Nutrition 0.000 description 1
- 239000004220 glutamic acid Substances 0.000 description 1
- YAMHXTCMCPHKLN-UHFFFAOYSA-N imidazolidin-2-one Chemical compound O=C1NCCN1 YAMHXTCMCPHKLN-UHFFFAOYSA-N 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 1
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- 238000005259 measurement Methods 0.000 description 1
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- 230000003204 osmotic effect Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- ACVYVLVWPXVTIT-UHFFFAOYSA-N phosphinic acid Chemical compound O[PH2]=O ACVYVLVWPXVTIT-UHFFFAOYSA-N 0.000 description 1
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Landscapes
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
Description
本発明は、逆浸透（ＲＯ：Reverse Osmosis）膜の洗浄方法に関し、より詳しくは、排水処理、特に、半導体や液晶等の電子材料の製造工程等の排水回収系における排水処理に用いられる逆浸透膜の洗浄方法に関する。 The present invention relates to a method for cleaning a reverse osmosis (RO) membrane, and more specifically, wastewater treatment, particularly reverse osmosis used in wastewater treatment in a wastewater recovery system such as a manufacturing process of electronic materials such as semiconductors and liquid crystals. The present invention relates to a method for cleaning a film.
逆浸透膜は、海水の淡水化や超純水の製造、排水処理等の種々の水処理に用いられている。これらの水処理に用いられる逆浸透膜は、継続使用によって、膜供給水中の除去対象物質等によるファウリングを生じる場合がある。特に、半導体や液晶等の電子材料の製造工程における排水回収系の排水処理に用いられる逆浸透膜においては、鉄等の金属成分（無機成分）に起因する無機ファウリングのみならず、ノニオン界面活性剤等に起因する有機ファウリングや、バイオファウリング等の様々な要因によるファウリングが生じる。 Reverse osmosis membranes are used in various water treatments such as seawater desalination, ultrapure water production, and wastewater treatment. The reverse osmosis membranes used in these water treatments may cause fouling due to substances to be removed in the membrane supply water due to continuous use. Especially in reverse osmosis membranes used for wastewater treatment in wastewater recovery systems in the manufacturing process of electronic materials such as semiconductors and liquid crystals, not only inorganic fouling caused by metal components (inorganic components) such as iron, but also nonionic surface activity Fouling due to various factors such as organic fouling and bio-fouling due to the agent occurs.
逆浸透膜にファウリングが生じると、膜の閉塞による水処理能力の低下や水処理装置の運転コストの増大を招くこととなる。このため、逆浸透膜を継続的に使用する場合には、ファウリング対策として、随時、洗浄が行われる。
無機ファウリングは、通常、酸により洗浄され、これによる膜性能の低下は比較的容易に回復させることができる。これに対して、有機ファウリングやバイオファウリング、さらに、これらに金属酸化物等が複合した汚染物質に起因するファウリングによる膜性能の低下を回復させることは比較的困難である。
When fouling occurs in the reverse osmosis membrane, the water treatment capacity is lowered due to the blockage of the membrane, and the operating cost of the water treatment apparatus is increased. For this reason, when the reverse osmosis membrane is continuously used, cleaning is performed as needed as a countermeasure against fouling.
Inorganic fouling is usually washed with an acid, and the deterioration of the membrane performance due to this can be recovered relatively easily. On the other hand, it is relatively difficult to recover the deterioration of film performance due to organic fouling, bio-fouling, and fouling caused by contaminants in which metal oxides are combined.
有機ファウリングやバイオファウリングに対する洗浄方法としては、例えば、非特許文献１に、バイオファウリングに対しては、高ｐＨのアルカリ洗浄液を用いて浸漬洗浄し、また、有機ファウリングに対しては、高ｐＨのアルカリ洗浄液を用いたアルカリ洗浄工程と、低ｐＨの洗浄液を用いた酸洗浄工程とを１セットとした浸漬洗浄を行うことが記載されている。 As a cleaning method for organic fouling and bio-fouling, for example, in Non-Patent Document 1, for bio-fouling, immersion cleaning is performed using a high pH alkaline cleaning solution, and for organic fouling. In addition, it is described that immersion cleaning is performed with one set of an alkali cleaning step using a high pH alkaline cleaning solution and an acid cleaning step using a low pH cleaning solution.
しかしながら、上記のような洗浄方法は、初回の洗浄効果は高いものの、継続的に使用される逆浸透膜に対して、随時、同じ方法で洗浄しても、洗浄効果が徐々に低下し、逆浸透膜の性能の回復率の低下度が大きくなるという課題を有していた。 However, although the cleaning method as described above has a high initial cleaning effect, even if the reverse osmosis membrane that is continuously used is cleaned by the same method at any time, the cleaning effect gradually decreases, and the reverse There was a problem that the degree of decrease in the recovery rate of the performance of the osmotic membrane was increased.
本発明は、上記技術的課題を解決するためになされたものであり、水処理に継続的に使用される逆浸透膜にファウリングが生じた際、より効果的に洗浄することができ、逆浸透膜の性能の回復率の低下を従来よりも抑えることができる、逆浸透膜の洗浄方法を提供することを目的とするものである。 The present invention has been made to solve the above technical problem, and when fouling occurs in a reverse osmosis membrane continuously used for water treatment, it can be washed more effectively. An object of the present invention is to provide a method for cleaning a reverse osmosis membrane, which can suppress a decrease in the recovery rate of the performance of the osmosis membrane as compared with the prior art.
本発明は、逆浸透膜の洗浄において、アミド化合物を含有するアルカリ洗浄液とキレート剤を含有するアルカリ洗浄液とを交替で用いることにより、洗浄後の逆浸透膜の透過流束の回復率が低下する程度を小さく抑えることができることを見出したことに基づくものである。 In the reverse osmosis membrane cleaning, the recovery rate of the permeation flux of the reverse osmosis membrane after cleaning is lowered by alternately using an alkaline cleaning solution containing an amide compound and an alkaline cleaning solution containing a chelating agent. This is based on the finding that the degree can be kept small.
すなわち、本発明は、以下の［１］〜［９］を提供するものである。
［１］ファウリングが生じた逆浸透膜を、定期又は不定期に複数回、アルカリ洗浄液を用いて洗浄する方法において、アミド化合物を含有し、かつキレート剤を含有しないアルカリ洗浄液１を用いる回と、キレート剤を含有し、かつアミド化合物を含有しないアルカリ洗浄液２を用いる回とを含む、逆浸透膜の洗浄方法。
［２］前記アミド化合物が芳香族アミドである、上記［１］に記載の逆浸透膜の洗浄方法。
［３］前記アルカリ洗浄液１及び前記アルカリ洗浄液２のうちの少なくともいずれかのアルカリ洗浄液が、界面活性剤をさらに含有する、上記［１］又は［２］に記載の逆浸透膜の洗浄方法。
［４］前記界面活性剤がアニオン系界面活性剤である、上記［３］に記載の逆浸透膜の洗浄方法。
［５］前記アルカリ洗浄液２が、還元剤をさらに含有する、上記［１］〜［４］のいずれか１項に記載の逆浸透膜の洗浄方法。
［６］前記アルカリ洗浄液１及び前記アルカリ洗浄液２のうちの少なくともいずれかのアルカリ洗浄液が、ｐＨ１０〜１３である、上記［１］〜［５］のいずれか１項に記載の逆浸透膜の洗浄方法。
That is, the present invention provides the following [1] to [9].
[1] In a method of cleaning a reverse osmosis membrane in which fouling has occurred regularly or irregularly using an alkaline cleaning solution a plurality of times, using an alkaline cleaning solution 1 containing an amide compound and not containing a chelating agent And a method of cleaning the reverse osmosis membrane, including the step of using the alkaline cleaning liquid 2 containing a chelating agent and not containing an amide compound.
[2] The reverse osmosis membrane cleaning method according to [1], wherein the amide compound is an aromatic amide.
[3] The reverse osmosis membrane cleaning method according to the above [1] or [2], wherein at least one of the alkaline cleaning liquid 1 and the alkaline cleaning liquid 2 further contains a surfactant.
[4] The reverse osmosis membrane cleaning method according to [3], wherein the surfactant is an anionic surfactant.
[5] The reverse osmosis membrane cleaning method according to any one of the above [1] to [4], wherein the alkaline cleaning liquid 2 further contains a reducing agent.
[6] The reverse osmosis membrane cleaning according to any one of [1] to [5] above, wherein the alkaline cleaning liquid of at least one of the alkaline cleaning liquid 1 and the alkaline cleaning liquid 2 has a pH of 10 to 13. Method.
［７］前記アルカリ洗浄液１を用いる回、及び前記アルカリ洗浄液２を用いる回のうちの少なくともいずれかの回において、各アルカリ洗浄液による洗浄の前もしくは後に、又は前後両方で酸洗浄液による洗浄を行う、上記［１］〜［６］のいずれか１項に記載の逆浸透膜の洗浄方法。
［８］前記酸洗浄液がｐＨ２〜４である、上記［７］に記載の逆浸透膜の洗浄方法。
［９］前記逆浸透膜がポリアミド系逆浸透膜である、上記［１］〜［８］のいずれか１項に記載の逆浸透膜の洗浄方法。
[7] In at least one of the times using the alkaline cleaning liquid 1 and the times using the alkaline cleaning liquid 2, cleaning with an acid cleaning liquid is performed before or after cleaning with each alkaline cleaning liquid, or both before and after. The method for cleaning a reverse osmosis membrane according to any one of [1] to [6] above.
[8] The reverse osmosis membrane cleaning method according to [7], wherein the acid cleaning solution has a pH of 2 to 4.
[9] The method for cleaning a reverse osmosis membrane according to any one of the above [1] to [8], wherein the reverse osmosis membrane is a polyamide-based reverse osmosis membrane.
本発明の逆浸透膜の洗浄方法によれば、水処理に継続的に使用される逆浸透膜にファウリングが生じた際、より効果的に洗浄することができ、逆浸透膜の性能の回復率の低下を従来よりも抑えることができる。
したがって、本発明の洗浄方法によれば、初回の洗浄と同等レベルの洗浄効果を、２回目以降の洗浄においても長期間にわたって維持することができるため、逆浸透膜の使用寿命を延ばすことができる。ひいては、逆浸透膜の水処理能力の低下の抑制や水処理装置の運転コストの増大の抑制にもつながる。
According to the reverse osmosis membrane cleaning method of the present invention, when fouling occurs in the reverse osmosis membrane continuously used for water treatment, the reverse osmosis membrane can be more effectively cleaned and the performance of the reverse osmosis membrane can be recovered. The decrease in rate can be suppressed as compared with the conventional case.
Therefore, according to the cleaning method of the present invention, the cleaning effect of the same level as that of the first cleaning can be maintained over a long period of time in the second and subsequent cleanings, so that the service life of the reverse osmosis membrane can be extended. . As a result, it leads to suppression of the fall of the water treatment capability of a reverse osmosis membrane, and suppression of the increase in the operating cost of a water treatment apparatus.
以下、本発明について詳細に説明する。
本発明の逆浸透膜の洗浄方法は、ファウリングが生じた逆浸透膜を、定期又は不定期に複数回、アルカリ洗浄液を用いて洗浄する方法である。そして、アミド化合物を含有し、かつキレート剤を含有しないアルカリ洗浄液１を用いる回と、キレート剤を含有し、かつアミド化合物を含有しないアルカリ洗浄液２を用いる回とを含むことを特徴とする。
このように、逆浸透膜の複数回の洗浄において、２種類のアルカリ洗浄液１及び２を交替で用いることにより、逆浸透膜の性能の回復率の低下を従来よりも抑えることができる。また、洗浄のいずれの回でも、アミド化合物及びキレート剤を含有するアルカリ洗浄液を用いる場合よりも、良好な洗浄効果を得ることができ、洗浄液のコスト面においても有利である。
なお、ここで言う「交替」とは、アルカリ洗浄液１又は２のいずれか一方から他方への１回限りの変更の場合も、相互の変更が複数回繰り返される場合も含むものとする。
Hereinafter, the present invention will be described in detail.
The reverse osmosis membrane cleaning method of the present invention is a method of cleaning a reverse osmosis membrane in which fouling has occurred, using an alkaline cleaning liquid a plurality of times regularly or irregularly. And it includes the time of using the alkaline cleaning liquid 1 containing an amide compound and not containing a chelating agent, and the time of using the alkaline cleaning liquid 2 containing a chelating agent and not containing an amide compound.
In this way, in the multiple washing of the reverse osmosis membrane, by using the two types of alkaline cleaning liquids 1 and 2 alternately, it is possible to suppress a reduction in the recovery rate of the reverse osmosis membrane performance as compared with the conventional case. Further, at any time of cleaning, a better cleaning effect can be obtained than in the case of using an alkaline cleaning liquid containing an amide compound and a chelating agent, which is advantageous in terms of the cost of the cleaning liquid.
In addition, the “replacement” referred to here includes both a case where the alkaline cleaning liquid 1 or 2 is changed only once and the case where the mutual change is repeated a plurality of times.
［逆浸透膜］
本発明における洗浄対象である逆浸透膜は、海水の淡水化や超純水の製造、排水処理等の種々の水処理に使用されて、ファウリングが生じた逆浸透膜である。
逆浸透膜の材質は、芳香族ポリアミド等のポリアミド系や、酢酸セルロース系等の水処理用逆浸透膜において公知のものでよく、本発明の洗浄方法は、特に、ポリアミド系逆浸透膜の洗浄に効果的である。
また、本発明は、従来の洗浄液では十分な洗浄効果を得ることができない逆浸透膜、特に、有機ファウリングやバイオファウリングが生じた逆浸透膜に効果的である。
[Reverse osmosis membrane]
The reverse osmosis membrane to be cleaned in the present invention is a reverse osmosis membrane that has been used for various water treatments such as desalination of seawater, production of ultrapure water, and wastewater treatment, and fouling has occurred.
The material of the reverse osmosis membrane may be a known material for water treatment reverse osmosis membranes such as polyamides such as aromatic polyamides and cellulose acetates, and the cleaning method of the present invention is particularly suitable for cleaning polyamide reverse osmosis membranes. It is effective.
In addition, the present invention is effective for reverse osmosis membranes in which sufficient cleaning effects cannot be obtained with conventional cleaning liquids, particularly for reverse osmosis membranes in which organic fouling or biofouling has occurred.
［アルカリ洗浄液１］
アルカリ洗浄液１は、アミド化合物を含有し、かつキレート剤を含有しない、高ｐＨの洗浄液である。
アルカリ洗浄液１は、アミド化合物の他に、例えば、アルカリ剤及び界面活性剤等の薬剤、並びに溶媒等を含んでいてもよいが、キレート剤は含まない。アルカリ洗浄液１は、１液型でも、あるいはまた、２剤以上からなり、これらが混合されてなるものであってもよく、通常、水溶液として用いられる。また、高濃度又は固形剤を水等の溶媒で希釈又は溶解して調製されたものであってもよい。
[Alkali cleaning solution 1]
The alkaline cleaning liquid 1 is a high pH cleaning liquid that contains an amide compound and does not contain a chelating agent.
In addition to the amide compound, the alkaline cleaning liquid 1 may contain, for example, a chemical agent such as an alkaline agent and a surfactant, and a solvent, but does not contain a chelating agent. The alkaline cleaning liquid 1 may be a one-pack type, or may be composed of two or more agents mixed with each other, and is usually used as an aqueous solution. Alternatively, it may be prepared by diluting or dissolving a high concentration or solid agent with a solvent such as water.
アルカリ洗浄液１のｐＨは、アミド化合物による洗浄効果の観点から、８以上であることが好ましく、また、逆浸透膜の劣化を抑制する観点から、１４以下であることが好ましく、より好ましくは９〜１４であり、さらに好ましくは１０〜１３である。所望のｐＨの調整は、アルカリ剤の添加により行うことができる。 The pH of the alkaline cleaning liquid 1 is preferably 8 or more from the viewpoint of the cleaning effect by the amide compound, and is preferably 14 or less from the viewpoint of suppressing the deterioration of the reverse osmosis membrane, more preferably 9 to 14, more preferably 10-13. The desired pH can be adjusted by adding an alkali agent.
＜アミド化合物＞
アミド化合物による洗浄作用の機構は明らかではないが、アミド化合物のアミド結合部位が、逆浸透膜とファウリングの原因物質との間に浸透し、該原因物質の膜表面からの剥離を促す作用を奏するものと考えられる。特に、ポリアミド系逆浸透膜は、アミド結合部位を有している点で、該アミド化合物と共通していることから、該アミド化合物との親和性が高く、前記原因物質の剥離作用がより促されるものと推測される。
したがって、アミド化合物は、逆浸透膜とファウリングの原因物質との間に浸透しやすいものであることが好ましく、このような観点から、水に対して可溶性を有していることが好ましい。また、良好な洗浄効果を得る観点から、分子量３００以下と比較的低分子量であることが好ましく、より好ましくは２５０以下、より好ましくは２００以下である。
<Amide compound>
The mechanism of the cleaning action by the amide compound is not clear, but the amide binding site of the amide compound penetrates between the reverse osmosis membrane and the causative substance of fouling, and promotes the peeling of the causative substance from the membrane surface. It is thought to play. In particular, since the polyamide-based reverse osmosis membrane has an amide bond site and is in common with the amide compound, the polyamide-based reverse osmosis membrane has a high affinity with the amide compound and further promotes the peeling action of the causative substance. It is speculated that
Therefore, the amide compound is preferably one that easily permeates between the reverse osmosis membrane and the causative substance of fouling. From such a viewpoint, the amide compound is preferably soluble in water. Further, from the viewpoint of obtaining a good cleaning effect, the molecular weight is preferably 300 or less and relatively low molecular weight, more preferably 250 or less, more preferably 200 or less.
前記アミド化合物としては、洗浄効果の観点から、カルボン酸アミドが好ましい。具体的には、ニコチンアミド、ベンズアミド、ｐ−アミノベンズアミド、フタルアミド、テレフタルアミド、フタルアミド酸、馬尿酸、ベンズアニリド及びｐ−アミノベンズアニリド等の芳香族アミド；Ｌ−アスパラギン、Ｌ−グルタミン、ホルミアミド、アセトアミド、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド及びピラセタム等の脂肪族アミド；２−ピロリドン、Ｎ−メチルピロリドン、１−エチル−２−ピロリドン、Ｎ−ビニル−２−ピロリドン、Ｌ−ピログルタミン酸及び２−イミダゾリジノン等の環状アミドが挙げられる。これらのうち、１種単独で用いても、２種以上を併用してもよい。
良好な洗浄効果を得る観点からは、アミド化合物としては、芳香族アミドを用いることが好ましく、これらのうち、水溶性の観点から、ニコチンアミド、ベンズアミド、ｐ−アミノベンズアミド、フタルアミド、フタルアミド酸又は馬尿酸がより好ましく、さらに好ましくはニコチンアミド又はベンズアミドである。
The amide compound is preferably a carboxylic acid amide from the viewpoint of cleaning effect. Specifically, aromatic amides such as nicotinamide, benzamide, p-aminobenzamide, phthalamide, terephthalamide, phthalamic acid, hippuric acid, benzanilide and p-aminobenzanilide; L-asparagine, L-glutamine, formamide, acetamide Aliphatic amides such as N, N-dimethylformamide, N, N-dimethylacetamide and Piracetam; 2-pyrrolidone, N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, L-pyro And cyclic amides such as glutamic acid and 2-imidazolidinone. Among these, it may be used alone or in combination of two or more.
From the viewpoint of obtaining a good cleaning effect, it is preferable to use an aromatic amide as the amide compound. Among these, from the viewpoint of water solubility, nicotinamide, benzamide, p-aminobenzamide, phthalamide, phthalamic acid, or horse Uric acid is more preferable, and nicotinamide or benzamide is more preferable.
アルカリ洗浄液１中のアミド化合物の含有量は、アミド化合物の種類や洗浄液のｐＨ、洗浄液中の他の併用薬剤等により異なり、適宜設定されるが、十分な洗浄効果が得られる量とする観点から、通常、０．１〜１０質量％であることが好ましく、より好ましくは０．２〜８質量％、さらに好ましくは０．５〜５質量％である。 The content of the amide compound in the alkaline cleaning liquid 1 varies depending on the type of the amide compound, the pH of the cleaning liquid, other concomitant drugs in the cleaning liquid, and the like, and is set as appropriate. From the viewpoint of obtaining a sufficient cleaning effect. Usually, it is preferably 0.1 to 10% by mass, more preferably 0.2 to 8% by mass, and still more preferably 0.5 to 5% by mass.
＜その他の成分＞
アミド化合物以外に、アルカリ洗浄液１に含まれ得る薬剤としては、例えば、アルカリ剤、界面活性剤等が挙げられる。これらの薬剤のうち、１種単独で用いられても、２種以上が併用されてもよい。
<Other ingredients>
As a chemical | medical agent which can be contained in the alkaline cleaning liquid 1 other than an amide compound, an alkaline agent, surfactant, etc. are mentioned, for example. Among these drugs, one kind may be used alone, or two or more kinds may be used in combination.
アルカリ剤は、アルカリ洗浄液１を所望のｐＨとなるように調整するために添加される。アルカリ剤としては、例えば、水酸化ナトリウム及び水酸化カリウム等のアルカリ金属の水酸化物を用いることができる。 The alkaline agent is added to adjust the alkaline cleaning liquid 1 to have a desired pH. As the alkali agent, for example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide can be used.
界面活性剤は、アルカリ洗浄液１中の各薬剤の分散効果を高め、洗浄効果を向上させる観点から添加されることが好ましい。界面活性剤としては、ドデシルベンゼンスルホン酸ナトリウム等のアルキルベンゼンスルホン酸塩；ドデシル硫酸ナトリウム等のアルキル硫酸塩のようなアニオン系界面活性剤、また、ジエチレングリコールモノメチルエーテル等のポリアルキレングリコールモノアルキルエーテルのようなノニオン系界面活性剤等が挙げられる。これらのうち、分散効果の観点から、アニオン系界面活性剤が好ましい。
界面活性剤の添加濃度は、分散効果及び洗浄効果の観点から、１〜１００００ｐｐｍであることが好ましく、好ましくは１０〜５０００ｐｐｍ、より好ましくは５０〜２０００ｐｐｍである。
The surfactant is preferably added from the viewpoint of enhancing the dispersion effect of each agent in the alkaline cleaning liquid 1 and improving the cleaning effect. Surfactants include alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate; anionic surfactants such as alkyl sulfate such as sodium dodecyl sulfate; and polyalkylene glycol monoalkyl ethers such as diethylene glycol monomethyl ether. Nonionic surfactants and the like. Of these, anionic surfactants are preferable from the viewpoint of dispersion effect.
The addition concentration of the surfactant is preferably 1 to 10000 ppm, preferably 10 to 5000 ppm, more preferably 50 to 2000 ppm from the viewpoints of the dispersion effect and the cleaning effect.
また、溶媒としては、アルカリ洗浄液１中の各薬剤の溶解性向上の観点から、水以外に有機溶媒を含有してもよく、例えば、エタノール等のアルコール類；エチレングリコール、プロピレングリコール及びブタンジオール等のポリオール類；モノエタノールアミン、ジエタノールアミン及びトリエタノールアミン等のアミン類、アセトン等のケトン類；ジメチルエーテル、ジエチルエーテル及びジエチレングリコールモノメチルエーテル等のエーテル類等が挙げられる。これらのうち、１種単独で用いられても、２種以上が併用されてもよい。 Moreover, as a solvent, from a viewpoint of the solubility improvement of each chemical | medical agent in the alkaline cleaning liquid 1, you may contain organic solvents other than water, for example, alcohols, such as ethanol; ethylene glycol, propylene glycol, butanediol, etc. Polyols; amines such as monoethanolamine, diethanolamine and triethanolamine; ketones such as acetone; ethers such as dimethyl ether, diethyl ether and diethylene glycol monomethyl ether. Among these, one kind may be used alone, or two or more kinds may be used in combination.
［アルカリ洗浄液２］
アルカリ洗浄液２は、キレート剤を含有し、かつアミド化合物を含有しない、高ｐＨの洗浄液である。
アルカリ洗浄液２は、キレート剤の他に、例えば、アルカリ剤、界面活性剤及び還元剤等の薬剤、並びに溶媒等を含んでいてもよいが、アミド化合物は含まない。アルカリ洗浄液２も、アルカリ洗浄液１と同様に、１液型でも、あるいはまた、２剤以上からなり、これらが混合されてなるものであってもよく、通常、水溶液として用いられる。また、高濃度又は固形剤を水等の溶媒で希釈又は溶解して調製されたものであってもよい。
[Alkaline cleaning solution 2]
The alkaline cleaning liquid 2 is a high pH cleaning liquid that contains a chelating agent and does not contain an amide compound.
In addition to the chelating agent, the alkali cleaning liquid 2 may contain, for example, an agent such as an alkali agent, a surfactant and a reducing agent, a solvent, etc., but does not contain an amide compound. Similarly to the alkaline cleaning liquid 1, the alkaline cleaning liquid 2 may be a one-pack type or may be a mixture of two or more agents, and these are usually used as an aqueous solution. Alternatively, it may be prepared by diluting or dissolving a high concentration or solid agent with a solvent such as water.
アルカリ洗浄液２のｐＨは、キレート剤による洗浄効果の観点から、８以上であることが好ましく、また、逆浸透膜の劣化を抑制する観点から、１４以下であることが好ましく、より好ましくは９〜１４であり、さらに好ましくは１０〜１３である。所望のｐＨの調整は、アルカリ剤の添加により行うことができる。 The pH of the alkaline cleaning liquid 2 is preferably 8 or more from the viewpoint of the cleaning effect by the chelating agent, and is preferably 14 or less from the viewpoint of suppressing the deterioration of the reverse osmosis membrane, more preferably 9 to 14, more preferably 10-13. The desired pH can be adjusted by adding an alkali agent.
＜キレート剤＞
キレート剤は、カルシウムやマグネシウム、鉄等の金属イオンを封鎖する金属封鎖作用を有するものであり、金属成分、特に有機金属成分に起因するファウリングに対する洗浄効果を奏するものである。
したがって、キレート剤は、良好な洗浄効果を得るために、逆浸透膜の膜表面に満遍なく分散することが好ましく、このような観点から、水に対して可溶性を有していることが好ましい。
<Chelating agent>
The chelating agent has a metal sequestering action to sequester metal ions such as calcium, magnesium, and iron, and has a cleaning effect on fouling caused by metal components, particularly organometallic components.
Accordingly, the chelating agent is preferably evenly dispersed on the membrane surface of the reverse osmosis membrane in order to obtain a good cleaning effect. From such a viewpoint, the chelating agent is preferably soluble in water.
前記キレート剤としては、例えば、エチレンジアミン四酢酸（ＥＤＴＡ）、グリコールエーテルジアミン四酢酸（ＥＧＴＡ）、ヘキサメタリン酸、ポリリン酸、ホスホノブタントリカルボン酸（ＰＢＴＣ）、ホスホン酸、ポリマレイン酸、クエン酸、シュウ酸、グルコン酸、及びこれらの塩等が挙げられる。これらのうち、１種単独で用いても、２種以上を併用してもよい。 Examples of the chelating agent include ethylenediaminetetraacetic acid (EDTA), glycol etherdiaminetetraacetic acid (EGTA), hexametaphosphoric acid, polyphosphoric acid, phosphonobutanetricarboxylic acid (PBTC), phosphonic acid, polymaleic acid, citric acid, and oxalic acid. , Gluconic acid, and salts thereof. Among these, it may be used alone or in combination of two or more.
アルカリ洗浄液２中のキレート剤の含有量は、キレート剤の種類や洗浄液のｐＨ、洗浄液中の他の併用薬剤等により異なり、適宜設定されるが、十分な洗浄効果が得られる量とする観点から、通常、１０〜２００００ｐｐｍであることが好ましく、好ましくは１００〜１００００ｐｐｍ、より好ましくは５００〜８０００ｐｐｍである。 The content of the chelating agent in the alkaline cleaning liquid 2 varies depending on the type of the chelating agent, the pH of the cleaning liquid, other concomitant drugs in the cleaning liquid, and the like, and is set as appropriate. From the viewpoint of obtaining an amount sufficient for a cleaning effect. Usually, it is preferably 10 to 20000 ppm, preferably 100 to 10000 ppm, more preferably 500 to 8000 ppm.
＜その他の成分＞
キレート剤以外に、アルカリ洗浄液２に含まれ得る薬剤としては、例えば、アルカリ剤、界面活性剤、還元剤等が挙げられる。これらの薬剤のうち、１種単独で用いられても、２種以上が併用されてもよい。
<Other ingredients>
In addition to the chelating agent, examples of the agent that can be contained in the alkaline cleaning liquid 2 include an alkali agent, a surfactant, and a reducing agent. Among these drugs, one kind may be used alone, or two or more kinds may be used in combination.
アルカリ剤は、アルカリ洗浄液２を所望のｐＨとなるように調整するために添加される。アルカリ剤としては、例えば、水酸化ナトリウム及び水酸化カリウム等のアルカリ金属の水酸化物を用いることができる。 The alkaline agent is added to adjust the alkaline cleaning liquid 2 to have a desired pH. As the alkali agent, for example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide can be used.
界面活性剤は、アルカリ洗浄液２中の各薬剤の分散効果を高め、洗浄効果を向上させる観点から添加されることが好ましい。界面活性剤としては、アルカリ洗浄液１に添加されるものと同様のものを用いることができ、ドデシルベンゼンスルホン酸ナトリウム等のアルキルベンゼンスルホン酸塩；ドデシル硫酸ナトリウム等のアルキル硫酸塩のようなアニオン系界面活性剤、また、ジエチレングリコールモノメチルエーテル等のポリアルキレングリコールモノアルキルエーテルのようなノニオン系界面活性剤等が挙げられる。これらのうち、分散効果の観点から、アニオン系界面活性剤が好ましい。
界面活性剤の添加濃度は、分散効果及び洗浄効果の観点から、１〜１００００ｐｐｍであることが好ましく、好ましくは１０〜５０００ｐｐｍ、より好ましくは５０〜２０００ｐｐｍである。
The surfactant is preferably added from the viewpoint of enhancing the dispersion effect of each chemical in the alkaline cleaning liquid 2 and improving the cleaning effect. As the surfactant, the same one as that added to the alkaline cleaning liquid 1 can be used, and an anionic interface such as an alkylbenzene sulfonate such as sodium dodecylbenzenesulfonate; an alkylsulfate such as sodium dodecylsulfate. Activators and nonionic surfactants such as polyalkylene glycol monoalkyl ethers such as diethylene glycol monomethyl ether can be used. Of these, anionic surfactants are preferable from the viewpoint of dispersion effect.
The addition concentration of the surfactant is preferably 1 to 10000 ppm, preferably 10 to 5000 ppm, more preferably 50 to 2000 ppm from the viewpoints of the dispersion effect and the cleaning effect.
還元剤は、ファウリングの原因となる金属成分を還元し、キレート剤の金属封鎖作用を補助する役割を有しており、また、前記金属成分を析出させて除去する機能も有している。このため、還元剤を添加することにより、逆浸透膜の洗浄効果をより向上させることができる。還元剤は、良好な洗浄効果を得るために、逆浸透膜の膜表面に満遍なく分散することが好ましく、このような観点から、水に対して可溶性を有していることが好ましい。還元剤としては、例えば、ホルムアルデヒドやヒドラジン、また、次亜リン酸、亜硫酸、重亜硫酸、及びメタ重亜硫酸、並びにこれらの塩、硫酸第一鉄、二酸化硫黄等が挙げられる。これらのうち、１種単独で用いても、２種以上を併用してもよい。これらのうち、重亜硫酸ナトリウム、亜硫酸ナトリウム又はヒドラジンが好ましい。
還元剤の添加濃度は、洗浄効果の観点から、１〜２００００ｐｐｍであることが好ましく、好ましくは１０〜１００００ｐｐｍ、より好ましくは１００〜５０００ｐｐｍである。
The reducing agent has a role of reducing the metal component causing fouling and assisting the metal sequestering action of the chelating agent, and also has a function of precipitating and removing the metal component. For this reason, the washing | cleaning effect of a reverse osmosis membrane can be improved more by adding a reducing agent. In order to obtain a good cleaning effect, the reducing agent is preferably dispersed evenly on the membrane surface of the reverse osmosis membrane. From such a viewpoint, the reducing agent is preferably soluble in water. Examples of the reducing agent include formaldehyde and hydrazine, hypophosphorous acid, sulfurous acid, bisulfurous acid, and metabisulfuric acid, and salts thereof, ferrous sulfate, sulfur dioxide, and the like. Among these, it may be used alone or in combination of two or more. Of these, sodium bisulfite, sodium sulfite or hydrazine is preferred.
The addition concentration of the reducing agent is preferably 1 to 20000 ppm, preferably 10 to 10000 ppm, more preferably 100 to 5000 ppm from the viewpoint of the cleaning effect.
また、溶媒としては、アルカリ洗浄液２中の各薬剤の溶解性向上の観点から、アルカリ洗浄液１と同様に、水以外に有機溶媒を含有してもよく、例えば、エタノール等のアルコール類；エチレングリコール、プロピレングリコール及びブタンジオール等のポリオール類；モノエタノールアミン、ジエタノールアミン及びトリエタノールアミン等のアミン類、アセトン等のケトン類；ジメチルエーテル、ジエチルエーテル及びジエチレングリコールモノメチルエーテル等のエーテル類等が挙げられる。これらのうち、１種単独で用いられても、２種以上が併用されてもよい。 Moreover, as a solvent, from a viewpoint of the solubility improvement of each chemical | medical agent in the alkaline washing | cleaning liquid 2, similarly to the alkaline washing | cleaning liquid 1, you may contain organic solvents other than water, for example, alcohols, such as ethanol; ethylene glycol Polyols such as propylene glycol and butanediol; amines such as monoethanolamine, diethanolamine and triethanolamine; ketones such as acetone; ethers such as dimethyl ether, diethyl ether and diethylene glycol monomethyl ether. Among these, one kind may be used alone, or two or more kinds may be used in combination.
［洗浄方法］
本発明の洗浄方法においては、ファウリングにより膜性能が所定の程度にまで低下する毎に、その都度、アルカリ洗浄液１又はアルカリ洗浄液２を用いた洗浄を１回行い、このような洗浄を継続的に複数回行う。
１回の洗浄を行う時期は、定期でも不定期でもいずれでもよい。例えば、排水処理に用いられる逆浸透膜においては、処理する汚染液の汚染の程度によって適宜設定され、通常、水処理効率の観点から、各回の間隔は、１〜６か月程度であることが好ましい。
[Cleaning method]
In the cleaning method of the present invention, each time the membrane performance is reduced to a predetermined level due to fouling, cleaning is performed once using the alkaline cleaning liquid 1 or the alkaline cleaning liquid 2, and such cleaning is continuously performed. Repeat several times.
The time for performing one cleaning may be either regular or irregular. For example, in a reverse osmosis membrane used for wastewater treatment, it is appropriately set depending on the degree of contamination of the contaminated liquid to be treated, and the interval between each time is usually about 1 to 6 months from the viewpoint of water treatment efficiency. preferable.
各回のアルカリ洗浄において、アルカリ洗浄液１又はアルカリ洗浄液２のいずれを用いるかは、特に限定されるものではなく、ファウリングの原因物質や程度等に応じて適宜設定される。アルカリ洗浄液１とアルカリ洗浄液２とを１回毎に交替して用いてもよく、また、アルカリ洗浄液１及び２のいずれか一方を複数回連続して用いた後、他方のアルカリ洗浄液に交替させてもよい。
目安としては、アルカリ洗浄液１及び２のいずれか一方を用いた洗浄を複数回連続して用いた後、逆浸透膜の透過流束の回復度が低下してきた場合、すなわち、十分な洗浄効果が得られなくなってきたと判断される場合に、その次の回の洗浄において、他方のアルカリ洗浄液に交替させるようにすることが好ましい。
Whether to use the alkaline cleaning liquid 1 or the alkaline cleaning liquid 2 in each alkali cleaning is not particularly limited, and is appropriately set according to the causative substance and degree of fouling. The alkaline cleaning liquid 1 and the alkaline cleaning liquid 2 may be used alternately every time, and after either one of the alkaline cleaning liquids 1 and 2 is used continuously several times, the other alkaline cleaning liquid is used instead. Also good.
As a guideline, when the degree of recovery of the permeation flux of the reverse osmosis membrane has decreased after a plurality of times of continuous washing using either one of the alkaline washing liquids 1 and 2, that is, a sufficient washing effect. In the case where it is determined that it is no longer obtained, it is preferable to replace the other alkaline cleaning liquid in the next cleaning.
アルカリ洗浄液１又は２を用いた逆浸透膜の洗浄は、各洗浄液に逆浸透膜を接触させればよく、特に限定されるものではない。例えば、逆浸透膜に対する通液の順方向又は逆方向に洗浄液を循環流通させる循環洗浄、又は、逆浸透膜を洗浄液に浸漬する浸漬洗浄により、洗浄することができる。１回の洗浄において、これらの複数の方法を組み合わせてもよい。 The cleaning of the reverse osmosis membrane using the alkaline cleaning liquid 1 or 2 is not particularly limited as long as the reverse osmosis membrane is brought into contact with each cleaning liquid. For example, the cleaning can be performed by circulating cleaning in which the cleaning liquid is circulated in the forward direction or reverse direction of the flow through the reverse osmosis membrane, or by immersion cleaning in which the reverse osmosis membrane is immersed in the cleaning liquid. You may combine these several methods in 1 time of washing | cleaning.
また、アルカリ洗浄液１又はアルカリ洗浄液２を用いた１回の洗浄において、各アルカリ洗浄液による洗浄の前又は後に、又は前後両方で酸洗浄液による洗浄を行ってもよい。このような酸洗浄を行うことにより、金属成分に起因するスケールや金属コロイド等によるファウリングに対して有効な洗浄効果が得られる。
酸洗浄液による洗浄は、複数回のアルカリ洗浄液（アルカリ洗浄液１又は２）を用いた洗浄のうちの１回のみにおいて行ってもよく、あるいはまた、２回以上、さらにいずれの回においても行うようにしてもよい。
Further, in one cleaning using the alkaline cleaning liquid 1 or the alkaline cleaning liquid 2, cleaning with the acid cleaning liquid may be performed before or after the cleaning with each alkaline cleaning liquid, or both before and after. By performing such acid cleaning, an effective cleaning effect can be obtained against fouling caused by scales, metal colloids, and the like caused by metal components.
The cleaning with the acid cleaning liquid may be performed only once among the cleanings using a plurality of alkaline cleaning liquids (alkaline cleaning liquid 1 or 2), or may be performed twice or more, and at any time. May be.
酸洗浄液としては、例えば、塩酸、硝酸、クエン酸、シュウ酸等の酸を含む水溶液を用いることができる。これらの酸は、１種単独で用いても、２種以上を併用してもよい。
酸洗浄液のｐＨは、洗浄効果の観点から、５以下であることが好ましく、また、逆浸透膜の劣化を抑制する観点から、１以上であることが好ましく、より好ましくは２〜４、さらに好ましくは３〜４である。
As the acid cleaning solution, for example, an aqueous solution containing an acid such as hydrochloric acid, nitric acid, citric acid, or oxalic acid can be used. These acids may be used alone or in combination of two or more.
The pH of the acid cleaning solution is preferably 5 or less from the viewpoint of the cleaning effect, and is preferably 1 or more, more preferably 2 to 4, more preferably from the viewpoint of suppressing the deterioration of the reverse osmosis membrane. Is 3-4.
各洗浄液による洗浄時間は、特に限定されるものではなく、ファウリングの原因物質や程度等に応じて適宜設定される。逆浸透膜の膜性能が回復するのに十分な時間とする観点から、また、膜の劣化を考慮して、通常、０．５〜４８時間程度とする。 The cleaning time with each cleaning liquid is not particularly limited, and is appropriately set according to the cause and degree of fouling. From the viewpoint of setting the time sufficient for the membrane performance of the reverse osmosis membrane to recover, and taking into consideration the deterioration of the membrane, the time is usually about 0.5 to 48 hours.
各洗浄液による洗浄後は、通常、逆浸透膜に純水等の高純度水を流通させてリンスする。その後、逆浸透膜を再使用に供する。 After washing with each washing solution, usually, high purity water such as pure water is circulated through the reverse osmosis membrane for rinsing. Thereafter, the reverse osmosis membrane is reused.
以下、本発明をより詳細に説明するが、本発明は下記実施例により限定されるものではない。 Hereinafter, the present invention will be described in more detail, but the present invention is not limited to the following examples.
［試験１］アミド化合物を含有するアルカリ洗浄液による洗浄効果の確認
擬似排水を流通させることによってファウリングが生じた逆浸透膜（汚染膜）を、各種洗浄液試料を用いて洗浄した。このときの逆浸透膜の膜性能について、下記に示す評価を行った。なお、評価温度は２５℃（標準温度）とした。評価条件を以下に示す。
＜逆浸透膜＞
芳香族ポリアミド系逆浸透膜：「ＥＳ−２０」、日東電工株式会社製；平膜；有効膜面積（Ｓ）：８．０４×１０-4［ｍ2］、温度換算係数α＝１．０２４（２５−ｔ）（ｔ：温度［℃］）
[Test 1] Confirmation of cleaning effect by alkaline cleaning liquid containing amide compound A reverse osmosis membrane (contamination membrane) in which fouling was caused by circulating simulated waste water was cleaned using various cleaning liquid samples. The following evaluation was performed about the membrane performance of the reverse osmosis membrane at this time. The evaluation temperature was 25 ° C. (standard temperature). Evaluation conditions are shown below.
<Reverse osmosis membrane>
Aromatic polyamide-based reverse osmosis membrane: “ES-20”, manufactured by Nitto Denko Corporation; flat membrane; effective membrane area (S): 8.04 × 10 −4 [m 2 ], temperature conversion coefficient α = 1.024 (25-t) (t: temperature [° C.])
＜洗浄液＞
各洗浄液試料は、いずれも、水酸化ナトリウム（ＮａＯＨ）添加によりｐＨ１２に調整した。
（試料１）２質量％ニコチンアミド＋ＮａＯＨの水溶液
（試料２）１質量％ベンズアミド＋ＮａＯＨの水溶液
（試料３）２質量％ニコチンアミド＋１５００ｐｐｍドデシルベンゼンスルホン酸ナトリウム（ＳＤＢＳ）＋ＮａＯＨの水溶液
（試料４）ＮａＯＨ水溶液
（試料５）１５００ｐｐｍＳＤＢＳ＋ＮａＯＨの水溶液
<Cleaning liquid>
Each cleaning liquid sample was adjusted to pH 12 by adding sodium hydroxide (NaOH).
(Sample 1) 2% by weight nicotinamide + NaOH aqueous solution (Sample 2) 1% by weight benzamide + NaOH aqueous solution (Sample 3) 2% by weight nicotinamide + 1500 ppm sodium dodecylbenzenesulfonate (SDBS) + NaOH aqueous solution (Sample 4) NaOH aqueous solution (Sample 5) 1500 ppm SDBS + NaOH aqueous solution
＜擬似排水＞
ガラス基材用洗浄剤（「セミクリーンＫＧ」、横浜油脂工業株式会社製）を含む水溶液；ノニオン系界面活性剤含有濃度２００ｐｐｍ
＜洗浄方法＞
上記各試料の洗浄液を用いて、循環洗浄を２時間、浸漬洗浄を１５時間、及び循環洗浄を２時間、順次行った。循環洗浄時の透過圧力は０．２ＭＰａ（ゲージ圧；以下、同様。）とした。
<Pseudo drainage>
Aqueous solution containing glass substrate cleaner (“Semi-clean KG”, manufactured by Yokohama Oils & Fats Co., Ltd.); Nonionic surfactant-containing concentration: 200 ppm
<Washing method>
Using the cleaning liquid of each sample, circulation cleaning was performed for 2 hours, immersion cleaning for 15 hours, and circulation cleaning for 2 hours. The permeation pressure during the circulation cleaning was 0.2 MPa (gauge pressure; the same applies hereinafter).
＜評価方法＞
以下の手順により、逆浸透膜の膜性能の評価を行った。
（１）逆浸透膜の新膜に、純水（ｐＨ７）を０．７５ＭＰａで２４時間流通させて、新膜の透過流束（Ｊｖ0）を求めた。次いで、５００ｐｐｍ塩化ナトリウム水溶液を０．７５ＭＰａで２４時間流通させて、脱塩率を求めた。
（２）その後、擬似排水を０．７５ＭＰａで３日間流通させて汚染膜を得た。この汚染膜（洗浄前の逆浸透膜）について、上記（１）と同様にして、純水の透過流束（Ｊｖ1）及び脱塩率を求めた。
（３）そして、前記汚染膜を上記洗浄方法により洗浄し、洗浄後の逆浸透膜について、上記（１）と同様にして、純水の透過流束（Ｊｖ2）及び脱塩率を求めた。
（４）上記の各測定結果から、新膜の透過流束（Ｊｖ0）に対する洗浄後の逆浸透膜の透過流束（Ｊｖ2）の比率（百分率）を算出し、これを逆浸透膜の膜性能の回復率［％］とした。
なお、透過流束（Ｊｖ）は、逆浸透膜に対する純水の透過流量（Ｑ）を測定することにより、下記式から求められる。
Ｊｖ［ｍ3／（ｍ2・ｄａｙ）］＝Ｑ［ｍ3／ｄａｙ］／Ｓ［ｍ2］×α
上記式において、Ｓ：有効膜面積、α：温度換算係数を表す。なお、温度換算係数αは、使用する膜に固有の温度に対応して定められた値であり、標準温度２５℃における値に換算するための係数である。
また、脱塩率（ＳＲ）は、逆浸透膜の透過液の電気伝導率（σｐ）及び濃縮液の電気伝導率（σｃ）を測定することにより、下記式から求められる。
ＳＲ［％］＝（１−σｐ［ｍＳ／ｍ］／σｃ［ｍＳ／ｍ］）×１００
<Evaluation method>
The membrane performance of the reverse osmosis membrane was evaluated by the following procedure.
(1) Pure water (pH 7) was passed through the new membrane of the reverse osmosis membrane at 0.75 MPa for 24 hours, and the permeation flux (Jv 0 ) of the new membrane was determined. Next, a 500 ppm sodium chloride aqueous solution was circulated at 0.75 MPa for 24 hours to obtain a desalting rate.
(2) Thereafter, simulated waste water was circulated at 0.75 MPa for 3 days to obtain a contaminated film. For this contaminated membrane (reverse osmosis membrane before washing), the permeation flux (Jv 1 ) and desalting rate of pure water were determined in the same manner as in (1) above.
(3) Then, the contaminated membrane was washed by the washing method, and the permeation flux (Jv 2 ) and desalting rate of pure water were determined for the reverse osmosis membrane after washing in the same manner as in (1) above. .
(4) From the above measurement results, the ratio (percentage) of the permeation flux (Jv 2 ) of the reverse osmosis membrane after washing to the permeation flux (Jv 0 ) of the new membrane was calculated, and this was calculated. The recovery rate of the film performance was taken as [%].
The permeation flux (Jv) is obtained from the following equation by measuring the permeation flow rate (Q) of pure water with respect to the reverse osmosis membrane.
Jv [m 3 / (m 2 · day)] = Q [m 3 / day] / S [m 2 ] × α
In the above formula, S: effective membrane area, α: temperature conversion coefficient. The temperature conversion coefficient α is a value determined corresponding to the temperature unique to the film to be used, and is a coefficient for conversion into a value at a standard temperature of 25 ° C.
Further, the desalting rate (SR) is obtained from the following formula by measuring the electrical conductivity (σp) of the permeated liquid of the reverse osmosis membrane and the electrical conductivity (σc) of the concentrated liquid.
SR [%] = (1−σp [mS / m] / σc [mS / m]) × 100
各洗浄液試料について、上記評価方法により求められた各透過流束及び洗浄前後でのその変化量、並びに回復率を下記表１にまとめて示す。また、脱塩率は、いずれにおいても、９７〜９９％と高い値を示していた。 For each cleaning liquid sample, the permeation flux obtained by the above evaluation method, the amount of change before and after cleaning, and the recovery rate are summarized in Table 1 below. Moreover, the salt rejection showed a high value of 97 to 99% in all cases.
表１に示した結果から分かるように、アミド化合物を用いたアルカリ洗浄液を用いた場合（試料１〜３）は、膜性能の回復率が高く、脱塩率も高く維持されていることから、離良好な洗浄効果が得られることが認められた。特に、ドデシルベンゼンスルホン酸ナトリウム（アニオン系界面活性剤）を併用した場合（試料３）は、より優れた洗浄効果が得られると言える。 As can be seen from the results shown in Table 1, when an alkaline cleaning liquid using an amide compound is used (Samples 1 to 3), the membrane performance recovery rate is high and the desalination rate is maintained high. It was confirmed that a good cleaning effect was obtained. In particular, when sodium dodecylbenzenesulfonate (anionic surfactant) is used in combination (Sample 3), it can be said that a more excellent cleaning effect can be obtained.
［実施例１］
擬似排水を流通させた逆浸透膜（汚染膜）を、アルカリ洗浄液１及び２を用いた交替洗浄により、６回洗浄した。逆浸透膜に擬似排水を０．７５ＭＰａで１．５時間流通させる毎に、１回洗浄した。
各回の洗浄毎に、逆浸透膜の膜性能の回復率及び脱塩率を評価した。アルカリ洗浄液１による洗浄を３回行った時点で回復率が低下し、４回目の洗浄においても回復率の大幅な上昇は見られなかったため、５回目の洗浄からアルカリ洗浄液２による洗浄に交替して行った。
上記洗浄における評価条件を以下に示す。なお、評価温度は２５℃（標準温度）とした。
＜逆浸透膜＞
芳香族ポリアミド系逆浸透膜：「ＥＳ−２０」、日東電工株式会社製；平膜；有効膜面積（Ｓ）：８．０４×１０-4［ｍ2］
[Example 1]
The reverse osmosis membrane (contamination membrane) through which the simulated waste water was circulated was washed six times by alternate washing using the alkaline washing liquids 1 and 2. Each time the pseudo drainage was passed through the reverse osmosis membrane at 0.75 MPa for 1.5 hours, it was washed once.
For each washing, the recovery rate and desalting rate of the reverse osmosis membrane performance were evaluated. When the washing with the alkaline cleaning liquid 1 was performed three times, the recovery rate decreased, and no significant increase in the recovery rate was observed in the fourth cleaning, so that the cleaning with the alkaline cleaning liquid 2 was replaced with the fifth cleaning. went.
The evaluation conditions in the above washing are shown below. The evaluation temperature was 25 ° C. (standard temperature).
<Reverse osmosis membrane>
Aromatic polyamide-based reverse osmosis membrane: “ES-20”, manufactured by Nitto Denko Corporation; flat membrane; effective membrane area (S): 8.04 × 10 −4 [m 2 ]
＜洗浄液＞
各洗浄液は、いずれも、水酸化ナトリウム（ＮａＯＨ）添加によりｐＨ１２に調整した。
・アルカリ洗浄液１：２質量％ニコチンアミド＋５０ｐｐｍドデシル硫酸ナトリウム＋ＮａＯＨの水溶液
・アルカリ洗浄液２：５０００ｐｐｍグルコン酸ナトリウム＋５０ｐｐｍドデシル硫酸ナトリウム＋ＮａＯＨの水溶液
<Cleaning liquid>
Each cleaning solution was adjusted to pH 12 by adding sodium hydroxide (NaOH).
-Alkaline cleaning solution 1: 2 mass% nicotinamide + 50 ppm sodium dodecyl sulfate + NaOH aqueous solution-Alkaline cleaning solution 2: 5000 ppm sodium gluconate + 50 ppm sodium dodecyl sulfate + NaOH aqueous solution
＜擬似排水＞
ノニオン系界面活性剤（ポリオキシエチレンポリオキシプロピレンモノアルキルエーテル；アルキル基の炭素数１６〜１８）含有量５０ｐｐｍ＋鉄分含有量（塩化第二鉄由来）０．５ｐｐｍ＋塩化ナトリウム含有量３００ｐｐｍの水溶液；Ｍアルカリ度１０ｐｐｍ；カルシウム硬度１０ｐｐｍ；ｐＨ７
＜各回の洗浄方法＞
アルカリ洗浄液１又は２のいずれかを用いて、循環洗浄を１時間、浸漬洗浄を１時間、及び循環洗浄を１時間、順次行った。循環洗浄時の透過圧力は約０．７５ＭＰａとした。
<Pseudo drainage>
Nonionic surfactant (polyoxyethylene polyoxypropylene monoalkyl ether; alkyl group having 16 to 18 carbon atoms) content 50 ppm + iron content (derived from ferric chloride) 0.5 ppm + sodium chloride content 300 ppm aqueous solution; M Alkalinity 10 ppm; calcium hardness 10 ppm; pH 7
<How to wash each time>
Using either the alkaline cleaning solution 1 or 2, circulating cleaning was performed for 1 hour, immersion cleaning for 1 hour, and circulating cleaning for 1 hour. The permeation pressure during the circulation cleaning was set to about 0.75 MPa.
＜回復率の評価＞
逆浸透膜に純水（２５℃）を０．７５ＭＰａで２４時間流通させた後、逆浸透膜の透過流束を求めた。
新膜の透過流束に対する各回の洗浄後の透過流束の比率（百分率）を算出し、これを逆浸透膜の膜性能の回復率［％］とした。
＜脱塩率の評価＞
逆浸透膜にｐＨ７の５００ｐｐｍ塩化ナトリウム水溶液を０．７５ＭＰａで１時間流通させて、上記試験１と同様にして、脱塩率を求めた。
<Evaluation of recovery rate>
After flowing pure water (25 ° C.) through the reverse osmosis membrane at 0.75 MPa for 24 hours, the permeation flux of the reverse osmosis membrane was determined.
The ratio (percentage) of the permeation flux after each washing to the permeation flux of the new membrane was calculated and used as the recovery rate [%] of the membrane performance of the reverse osmosis membrane.
<Evaluation of desalination rate>
A 500 ppm sodium chloride aqueous solution with a pH of 7 was passed through the reverse osmosis membrane at 0.75 MPa for 1 hour, and the desalting rate was determined in the same manner as in Test 1 above.
新膜及び各回の洗浄前後での透過流量及びその変化量、並びに回復率及び脱塩率を下記表２に示す。 The new membrane and the permeation flow rate before and after each washing, the amount of change, the recovery rate, and the desalination rate are shown in Table 2 below.
表２に示した結果から分かるように、アルカリ洗浄液１を用いた洗浄から、５回目の洗浄において、アルカリ洗浄液２を用いた洗浄に交替したことにより、回復率も脱塩率も向上した。このことから、アルカリ洗浄液１による洗浄及びアルカリ洗浄液２による洗浄を交替させて洗浄することにより、初回の洗浄と同等レベルの洗浄効果を、後の回の洗浄においても維持し得ると言える。 As can be seen from the results shown in Table 2, the recovery rate and the desalting rate were improved by switching from the cleaning using the alkaline cleaning liquid 1 to the cleaning using the alkaline cleaning liquid 2 in the fifth cleaning. From this, it can be said that the cleaning effect equivalent to that of the first cleaning can be maintained in the subsequent cleaning by performing the cleaning by replacing the cleaning with the alkaline cleaning liquid 1 and the cleaning with the alkaline cleaning liquid 2.
［実施例２］
工場の液晶製造工程の排水（ノニオン系界面活性剤及び鉄分含有）回収系に設置されている逆浸透膜モジュール（汚染膜）を、アルカリ洗浄液１による洗浄工程を含む洗浄１、及びアルカリ洗浄液２による洗浄工程を含む洗浄２の交替洗浄により、１か月毎に、６回洗浄した。
各回の洗浄毎に、逆浸透膜の膜性能の回復率を評価した。洗浄１を３回行ったところ、３回目の洗浄による回復率が低下していたため、４回目の洗浄は洗浄２に交替して行った。
上記洗浄において用いた逆浸透膜、洗浄液、及び各回の洗浄方法の詳細を以下に示す。
＜逆浸透膜＞
複合ポリアミド系逆浸透膜：「ＣＰＡ５−ＬＤ」、日東電工株式会社製；スパイラル型モジュール：有効膜面積（Ｓ）：３７．１［ｍ2］
[Example 2]
The reverse osmosis membrane module (contamination membrane) installed in the wastewater (containing nonionic surfactant and iron content) recovery system of the liquid crystal manufacturing process in the factory is washed with the washing step 1 including the washing step with the alkaline washing solution 1 and the alkaline washing solution 2 Washing was performed 6 times per month by alternate washing of washing 2 including a washing step.
The recovery rate of the reverse osmosis membrane performance was evaluated for each washing. When washing 1 was performed 3 times, the recovery rate due to the 3rd washing was decreased, so the 4th washing was performed in place of washing 2.
The details of the reverse osmosis membrane, the cleaning liquid, and each cleaning method used in the above cleaning are shown below.
<Reverse osmosis membrane>
Composite polyamide reverse osmosis membrane: “CPA5-LD”, manufactured by Nitto Denko Corporation; spiral module: effective membrane area (S): 37.1 [m 2 ]
＜洗浄液＞
各アルカリ洗浄液は、いずれも、水酸化ナトリウム（ＮａＯＨ）添加によりｐＨ１２に調整した。
（洗浄１）
・酸洗浄液：０．１質量％シュウ酸水溶液；ｐＨ２
・アルカリ洗浄液１：２質量％ニコチンアミド＋１５００ｐｐｍドデシル硫酸ナトリウム＋ＮａＯＨの水溶液
（洗浄２）
・酸洗浄液：０．１質量％シュウ酸水溶液；ｐＨ２
・アルカリ洗浄液２：１５００ｐｐｍヘキサメタリン酸ナトリウム＋１５００ｐｐｍドデシルベンゼンスルホン酸ナトリウム＋１５００ｐｐｍ重亜硫酸ナトリウム＋ＮａＯＨの水溶液
<Cleaning liquid>
Each alkaline cleaning solution was adjusted to pH 12 by adding sodium hydroxide (NaOH).
(Wash 1)
Acid cleaning solution: 0.1% by mass oxalic acid aqueous solution; pH 2
・ Alkaline cleaning solution 1: 2% by mass of nicotinamide + 1500 ppm sodium dodecyl sulfate + NaOH aqueous solution (cleaning 2)
Acid cleaning solution: 0.1% by mass oxalic acid aqueous solution; pH 2
・ Alkaline cleaning solution 2: 1500 ppm sodium hexametaphosphate + 1500 ppm sodium dodecylbenzenesulfonate + 1500 ppm sodium bisulfite + NaOH aqueous solution
＜各回の洗浄方法＞
洗浄１による洗浄を行う回、及び洗浄２による洗浄を行う回のいずれも、以下の手順により行った。
（１）逆浸透膜モジュールを排水回収系の運転ラインから洗浄ラインに切り換えた。
（２）酸洗浄液を用いて２時間循環洗浄を行った後、純水を流通させてリンスした。
（３）アルカリ洗浄液を用いて２時間循環洗浄を行った後、循環を止めて、１５時間浸漬洗浄を行った。再び、２時間循環洗浄を行った後、純水を流通させてリンスした。
（４）洗浄ラインから前記運転ラインに切り換えて、洗浄後の逆浸透膜モジュールを排水処理に供した。
<How to wash each time>
Both the time of washing by washing 1 and the time of washing by washing 2 were performed according to the following procedure.
(1) The reverse osmosis membrane module was switched from the wastewater recovery system operation line to the washing line.
(2) After carrying out circulation washing for 2 hours using an acid washing solution, pure water was circulated and rinsed.
(3) Circulating cleaning was performed for 2 hours using an alkaline cleaning solution, and then the circulation was stopped and immersion cleaning was performed for 15 hours. After carrying out circulation washing for 2 hours again, pure water was circulated and rinsed.
(4) The washing line was switched to the operation line, and the washed reverse osmosis membrane module was subjected to wastewater treatment.
＜回復率の評価＞
逆浸透膜モジュールに、純水（２５℃）を０．７５ＭＰａで２４時間流通させた後、逆浸透膜モジュール１本当たりの透過流量［ｍ3／（本・ｄａｙ）］を求めた。
新膜の透過流量に対する各回の洗浄後の透過流量の比率（百分率）を算出し、これを逆浸透膜の膜性能の回復率［％］とした。
<Evaluation of recovery rate>
After flowing pure water (25 ° C.) through the reverse osmosis membrane module at 0.75 MPa for 24 hours, the permeation flow rate [m 3 / (main · day)] per reverse osmosis membrane module was determined.
The ratio (percentage) of the permeation flow rate after each washing to the permeation flow rate of the new membrane was calculated, and this was taken as the recovery rate [%] of the reverse osmosis membrane performance.
新膜及び各回の洗浄前後での透過流量及びその変化量、並びに回復率を下記表３にまとめて示す。 The new membrane and the permeation flow rate before and after each washing, the amount of change, and the recovery rate are summarized in Table 3 below.
表３に示した結果から分かるように、アルカリ洗浄液１を用いた洗浄１から、アルカリ洗浄液２を用いた洗浄２に交替した４回目の洗浄において、回復率が向上し、良好な洗浄効果が得られることが認められた。このことから、アルカリ洗浄液１による洗浄のみを繰り返すよりも、アルカリ洗浄液２による洗浄と交替させる洗浄方法によれば、初回の洗浄と同等レベルの洗浄効果を、後の回の洗浄においても維持し得ると言える。 As can be seen from the results shown in Table 3, in the fourth cleaning in which the cleaning 1 using the alkaline cleaning liquid 1 is replaced with the cleaning 2 using the alkaline cleaning liquid 2, the recovery rate is improved and a good cleaning effect is obtained. It was recognized that Therefore, according to the cleaning method that replaces the cleaning with the alkaline cleaning liquid 2 rather than only the cleaning with the alkaline cleaning liquid 1, the cleaning effect equivalent to that of the first cleaning can be maintained in the subsequent cleaning. It can be said.
Claims (9)
アミド化合物を含有し、かつキレート剤を含有しないアルカリ洗浄液１を用いる回と、キレート剤を含有し、かつアミド化合物を含有しないアルカリ洗浄液２を用いる回とを含む、逆浸透膜の洗浄方法。 In the method of cleaning the reverse osmosis membrane in which fouling has occurred, using an alkaline cleaning solution, multiple times regularly or irregularly,
A method for cleaning a reverse osmosis membrane, comprising: using an alkaline cleaning solution 1 containing an amide compound and not containing a chelating agent; and using a alkaline cleaning solution 2 containing a chelating agent and not containing an amide compound.
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