JP7492873B2 - Water recovery method and water recovery device - Google Patents
Water recovery method and water recovery device Download PDFInfo
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- JP7492873B2 JP7492873B2 JP2020119877A JP2020119877A JP7492873B2 JP 7492873 B2 JP7492873 B2 JP 7492873B2 JP 2020119877 A JP2020119877 A JP 2020119877A JP 2020119877 A JP2020119877 A JP 2020119877A JP 7492873 B2 JP7492873 B2 JP 7492873B2
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 284
- 238000011084 recovery Methods 0.000 title claims description 64
- 238000000034 method Methods 0.000 title claims description 52
- 239000012528 membrane Substances 0.000 claims description 179
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 142
- 239000000203 mixture Substances 0.000 claims description 61
- 238000001223 reverse osmosis Methods 0.000 claims description 61
- CUILPNURFADTPE-UHFFFAOYSA-N hypobromous acid Chemical compound BrO CUILPNURFADTPE-UHFFFAOYSA-N 0.000 claims description 57
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 claims description 53
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 claims description 52
- 229910052794 bromium Inorganic materials 0.000 claims description 50
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 47
- 239000004202 carbamide Substances 0.000 claims description 47
- -1 sulfamic acid compound Chemical class 0.000 claims description 41
- 239000007800 oxidant agent Substances 0.000 claims description 35
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 32
- 239000000460 chlorine Substances 0.000 claims description 32
- 229910052801 chlorine Inorganic materials 0.000 claims description 32
- 230000000844 anti-bacterial effect Effects 0.000 claims description 30
- 239000003899 bactericide agent Substances 0.000 claims description 27
- 239000012466 permeate Substances 0.000 claims description 22
- 241000894006 Bacteria Species 0.000 claims description 18
- 239000010865 sewage Substances 0.000 claims description 14
- 239000004065 semiconductor Substances 0.000 claims description 9
- 239000000645 desinfectant Substances 0.000 claims description 7
- 238000005342 ion exchange Methods 0.000 claims description 6
- 238000000354 decomposition reaction Methods 0.000 claims description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 18
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 description 18
- 238000004519 manufacturing process Methods 0.000 description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 239000007795 chemical reaction product Substances 0.000 description 12
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 10
- 239000003513 alkali Substances 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 10
- JHJLBTNAGRQEKS-UHFFFAOYSA-M sodium bromide Chemical compound [Na+].[Br-] JHJLBTNAGRQEKS-UHFFFAOYSA-M 0.000 description 10
- 229910021529 ammonia Inorganic materials 0.000 description 9
- IIACRCGMVDHOTQ-UHFFFAOYSA-N sulfamic acid Chemical class NS(O)(=O)=O IIACRCGMVDHOTQ-UHFFFAOYSA-N 0.000 description 9
- SXDBWCPKPHAZSM-UHFFFAOYSA-N bromic acid Chemical compound OBr(=O)=O SXDBWCPKPHAZSM-UHFFFAOYSA-N 0.000 description 8
- SXDBWCPKPHAZSM-UHFFFAOYSA-M bromate Chemical class [O-]Br(=O)=O SXDBWCPKPHAZSM-UHFFFAOYSA-M 0.000 description 7
- 238000005259 measurement Methods 0.000 description 6
- LNOPIUAQISRISI-UHFFFAOYSA-N n'-hydroxy-2-propan-2-ylsulfonylethanimidamide Chemical compound CC(C)S(=O)(=O)CC(N)=NO LNOPIUAQISRISI-UHFFFAOYSA-N 0.000 description 6
- 229920002647 polyamide Polymers 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 239000003795 chemical substances by application Substances 0.000 description 5
- 239000011261 inert gas Substances 0.000 description 5
- 239000005416 organic matter Substances 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 239000012298 atmosphere Substances 0.000 description 4
- CODNYICXDISAEA-UHFFFAOYSA-N bromine monochloride Chemical compound BrCl CODNYICXDISAEA-UHFFFAOYSA-N 0.000 description 4
- 125000004432 carbon atom Chemical group C* 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 4
- 239000002270 dispersing agent Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 4
- 229920005597 polymer membrane Polymers 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 238000000108 ultra-filtration Methods 0.000 description 4
- 239000004952 Polyamide Substances 0.000 description 3
- 125000000217 alkyl group Chemical group 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 229910052736 halogen Inorganic materials 0.000 description 3
- 150000002367 halogens Chemical class 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 description 3
- 230000035755 proliferation Effects 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- QNGVNLMMEQUVQK-UHFFFAOYSA-N 4-n,4-n-diethylbenzene-1,4-diamine Chemical compound CCN(CC)C1=CC=C(N)C=C1 QNGVNLMMEQUVQK-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000003673 groundwater Substances 0.000 description 2
- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 description 2
- 238000001471 micro-filtration Methods 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 125000000962 organic group Chemical group 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- IOLCXVTUBQKXJR-UHFFFAOYSA-M potassium bromide Chemical compound [K+].[Br-] IOLCXVTUBQKXJR-UHFFFAOYSA-M 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000012086 standard solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- VYECFMCAAHMRNW-UHFFFAOYSA-N sulfamic acid Chemical compound NS(O)(=O)=O.NS(O)(=O)=O VYECFMCAAHMRNW-UHFFFAOYSA-N 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- BMYNFMYTOJXKLE-UHFFFAOYSA-N 3-azaniumyl-2-hydroxypropanoate Chemical compound NCC(O)C(O)=O BMYNFMYTOJXKLE-UHFFFAOYSA-N 0.000 description 1
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 1
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- ABLZXFCXXLZCGV-UHFFFAOYSA-N Phosphorous acid Chemical compound OP(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 229910001854 alkali hydroxide Inorganic materials 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- SWLVFNYSXGMGBS-UHFFFAOYSA-N ammonium bromide Chemical compound [NH4+].[Br-] SWLVFNYSXGMGBS-UHFFFAOYSA-N 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 159000000009 barium salts Chemical class 0.000 description 1
- BEHLMOQXOSLGHN-UHFFFAOYSA-N benzenamine sulfate Chemical compound OS(=O)(=O)NC1=CC=CC=C1 BEHLMOQXOSLGHN-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- FECFIIXKXJBOSU-UHFFFAOYSA-N butylsulfamic acid Chemical compound CCCCNS(O)(=O)=O FECFIIXKXJBOSU-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- OGQPUOLFKIMRMF-UHFFFAOYSA-N chlorosulfamic acid Chemical compound OS(=O)(=O)NCl OGQPUOLFKIMRMF-UHFFFAOYSA-N 0.000 description 1
- 150000001868 cobalt Chemical class 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- BAQKWXACUNEBOT-UHFFFAOYSA-N dibutylsulfamic acid Chemical compound CCCCN(S(O)(=O)=O)CCCC BAQKWXACUNEBOT-UHFFFAOYSA-N 0.000 description 1
- NXFNZLHFBJYCPG-UHFFFAOYSA-N diethylsulfamic acid Chemical compound CCN(CC)S(O)(=O)=O NXFNZLHFBJYCPG-UHFFFAOYSA-N 0.000 description 1
- YGNOYUCUPMACDT-UHFFFAOYSA-N dimethylsulfamic acid Chemical compound CN(C)S(O)(=O)=O YGNOYUCUPMACDT-UHFFFAOYSA-N 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- XRVWREPFYXZOPK-UHFFFAOYSA-N dipropylsulfamic acid Chemical compound CCCN(S(O)(=O)=O)CCC XRVWREPFYXZOPK-UHFFFAOYSA-N 0.000 description 1
- 230000035622 drinking Effects 0.000 description 1
- 230000001614 effect on membrane Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- IOISAJSHULNACL-UHFFFAOYSA-N ethyl(methyl)sulfamic acid Chemical compound CCN(C)S(O)(=O)=O IOISAJSHULNACL-UHFFFAOYSA-N 0.000 description 1
- SIVVHUQWDOGLJN-UHFFFAOYSA-N ethylsulfamic acid Chemical compound CCNS(O)(=O)=O SIVVHUQWDOGLJN-UHFFFAOYSA-N 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 150000002357 guanidines Chemical class 0.000 description 1
- 239000012510 hollow fiber Substances 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 239000011630 iodine Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 159000000014 iron salts Chemical class 0.000 description 1
- 238000004895 liquid chromatography mass spectrometry Methods 0.000 description 1
- 150000002696 manganese Chemical class 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- YZVQGLCYZLGIAM-UHFFFAOYSA-N methyl(propyl)sulfamic acid Chemical compound CCCN(C)S(O)(=O)=O YZVQGLCYZLGIAM-UHFFFAOYSA-N 0.000 description 1
- MYMDOKBFMTVEGE-UHFFFAOYSA-N methylsulfamic acid Chemical compound CNS(O)(=O)=O MYMDOKBFMTVEGE-UHFFFAOYSA-N 0.000 description 1
- 239000008239 natural water Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 150000002815 nickel Chemical class 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 238000001139 pH measurement Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229920001444 polymaleic acid Polymers 0.000 description 1
- 159000000001 potassium salts Chemical class 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- JWQSOOZHYMZRBT-UHFFFAOYSA-N propan-2-ylsulfamic acid Chemical compound CC(C)NS(O)(=O)=O JWQSOOZHYMZRBT-UHFFFAOYSA-N 0.000 description 1
- HLIBNTOXKQCYMV-UHFFFAOYSA-N propylsulfamic acid Chemical compound CCCNS(O)(=O)=O HLIBNTOXKQCYMV-UHFFFAOYSA-N 0.000 description 1
- 230000009291 secondary effect Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 1
- 235000019345 sodium thiosulphate Nutrition 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 159000000008 strontium salts Chemical class 0.000 description 1
- 239000008400 supply water Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000010977 unit operation Methods 0.000 description 1
- 150000003751 zinc Chemical class 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Landscapes
- Treatment Of Water By Oxidation Or Reduction (AREA)
- Water Treatment By Sorption (AREA)
- Biological Treatment Of Waste Water (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Treatment Of Water By Ion Exchange (AREA)
- Physical Water Treatments (AREA)
Description
本発明は、尿素を含む被処理水からの水回収方法および水回収装置に関する。 The present invention relates to a method and device for recovering water from treated water that contains urea.
近年では、水不足を背景として、飲料用や産業用の用途を問わず河川や地下水等からの取水が制限されてきている。半導体産業等の水を多量に使用する業種の工場においては特にその傾向が強く、天然水の代替として下水処理水等を工場給水等に利用する動きが見られる。 In recent years, water shortages have led to restrictions on the withdrawal of water from rivers and groundwater, regardless of whether it is for drinking or industrial use. This tendency is particularly strong in factories in industries that use large amounts of water, such as the semiconductor industry, and there is a movement to use treated sewage water as an alternative to natural water for factory water supply, etc.
下水処理水等の有機物を多く含む水からの水回収方法としては、例えば下水の二次処理水（標準活性汚泥等による生物処理水）を、限外ろ過膜等の除濁膜で除濁処理した後に逆浸透膜（ＲＯ膜）に通水して透過水を得る方法等が取られることがある。この方法では、除濁膜の生物等による閉塞を抑制するために、被処理水中に次亜塩素酸を添加する方法が取られることが普通である（特許文献１参照）。 One method for recovering water from water containing a large amount of organic matter, such as sewage treatment water, is to clarify the secondary sewage treatment water (biologically treated water using standard activated sludge, etc.) using a turbidity membrane such as an ultrafiltration membrane, and then pass the water through a reverse osmosis membrane (RO membrane) to obtain permeate. In this method, hypochlorous acid is usually added to the water being treated to prevent clogging of the turbidity membrane by organisms, etc. (see Patent Document 1).
下水処理水等の有機物含有水を水回収するにあたり、ＲＯ透過水の水質が重要である。特に、半導体工場の給水として利用する場合はＴＯＣの濃度が重要である。ＴＯＣ濃度は低いほど好ましく、十分にＴＯＣが低減された水（例えば、ＴＯＣ１０μｇ／Ｌ以下、好ましくは２μｇ／Ｌ以下）であれば、純水の原水としての再利用可能性があり、工場の取水量の削減に大きく貢献できる場合がある。 When recovering water containing organic matter, such as sewage treatment water, the quality of the RO permeate is important. In particular, when using it as supply water for semiconductor factories, the TOC concentration is important. The lower the TOC concentration, the better, and water with sufficiently reduced TOC (for example, TOC 10 μg/L or less, preferably 2 μg/L or less) can be reused as raw water for pure water, which can make a significant contribution to reducing the amount of water intake by the factory.
通常のＴＯＣ源となる有機物は前述の除濁膜、逆浸透膜でその大部分が除去される。場合によっては、逆浸透膜の後段にさらにＵＶやオゾンによる処理等が設けられる場合もある。しかし、下水処理水等の中に含まれる尿素（尿素濃度／５＝ＴＯＣ濃度）は上記のいずれの単位操作での除去率も低いため、回収水中のＴＯＣ源として残存し、回収先が制限されてしまうという課題がある。 Most of the organic matter that is a normal TOC source is removed by the aforementioned turbidity removal membrane and reverse osmosis membrane. In some cases, further UV or ozone treatment may be performed downstream of the reverse osmosis membrane. However, the removal rate of urea (urea concentration / 5 = TOC concentration) contained in sewage treatment water, etc. is low in any of the above unit operations, so it remains as a TOC source in the recovered water, which creates the problem of limiting where it can be recovered.
一方で、活性炭上に尿素分解菌を担持させて生物活性炭とすることによって、尿素を分解することが可能であることが知られている（特許文献２参照）。特許文献２の方法では、生物活性炭の被処理水中に結合塩素剤を注入することによって尿素を分解する菌種を優先菌種として尿素を分解している。被処理水中に次亜塩素酸を注入すると、この次亜塩素酸が生物活性炭に流入するために、尿素分解菌の生成が抑制され、尿素を効率的に除去することが困難であった。被処理水中に結合塩素剤を注入すれば活性炭と接触しても結合塩素が分解されにくいとしているが、活性炭処理水中の残留塩素濃度を０．０２～０．１ｍｇ／Ｌに調整して尿素分解菌が死滅しないように調整する必要があり、制御が難しく装置が複雑になる。また、被処理水の水質が変動した場合には、追従することが困難である。活性炭を複数段にして前段の活性炭で次亜塩素酸を除去する方法もあるが、設備が大きくなる。 On the other hand, it is known that urea can be decomposed by supporting urea-decomposing bacteria on activated carbon to make biological activated carbon (see Patent Document 2). In the method of Patent Document 2, urea is decomposed by injecting a combined chlorine agent into the water to be treated with biological activated carbon, with the urea-decomposing bacteria being the preferred species. When hypochlorous acid is injected into the water to be treated, this hypochlorous acid flows into the biological activated carbon, suppressing the production of urea-decomposing bacteria, making it difficult to efficiently remove urea. It is said that combined chlorine is less likely to be decomposed even when it comes into contact with activated carbon if a combined chlorine agent is injected into the water to be treated, but it is necessary to adjust the residual chlorine concentration in the activated carbon-treated water to 0.02 to 0.1 mg/L so that the urea-decomposing bacteria are not killed, which makes control difficult and the equipment complicated. In addition, it is difficult to follow if the water quality of the water to be treated changes. There is also a method of using multiple stages of activated carbon to remove hypochlorous acid with the activated carbon in the front stage, but this requires large equipment.
本発明の目的は、尿素を含む被処理水からの水回収において、除濁膜での生物等による閉塞を抑制することができ、かつ生物活性炭における閉塞を抑制し、尿素分解菌の生成を大きく抑制することなく、尿素の除去が可能である水回収方法および水回収装置を提供することにある。 The object of the present invention is to provide a water recovery method and water recovery device that can prevent clogging of the turbidity membrane by organisms and the like when recovering water from treated water that contains urea, and that can remove urea without significantly suppressing the production of urea-decomposing bacteria by preventing clogging of the biological activated carbon.
本発明は、尿素を含む被処理水について逆浸透膜処理を行い水回収する水回収方法であって、前記逆浸透膜処理の前処理として除濁膜処理、および担体である活性炭上に尿素分解菌を担持させた生物活性炭処理を順に行い、前記除濁膜処理の前段において殺菌剤を添加し、前記殺菌剤が、臭素系酸化剤とスルファミン酸化合物とを含む安定化次亜臭素酸組成物である、水回収方法である。 The present invention relates to a water recovery method for recovering water by performing reverse osmosis membrane treatment on urea-containing water to be treated, in which a turbidity removal membrane treatment and a biological activated carbon treatment in which urea-decomposing bacteria are supported on an activated carbon carrier are sequentially performed as pretreatments for the reverse osmosis membrane treatment, and a bactericide is added in the stage prior to the turbidity removal membrane treatment , the bactericide being a stabilized hypobromous acid composition containing a bromine-based oxidant and a sulfamic acid compound .
前記水回収方法において、前記除濁膜処理で得られる除濁膜処理水中の残留塩素濃度が０．０２～０．５ｍｇ－Ｃｌ２／Ｌの範囲となるように前記安定化次亜臭素酸組成物を添加することが好ましい。 In the water recovery method, it is preferable to add the stabilized hypobromous acid composition so that the residual chlorine concentration in the turbidity membrane treated water obtained in the turbidity membrane treatment is in the range of 0.02 to 0.5 mg-Cl 2 /L.
前記水回収方法において、前記被処理水が下水処理水であり、前記逆浸透膜処理の透過水を半導体工場の純水製造の原水として回収することが好ましい。 In the water recovery method, it is preferable that the water to be treated is sewage treatment water, and the permeate from the reverse osmosis membrane treatment is recovered as raw water for producing pure water in a semiconductor factory.
前記水回収方法における前記逆浸透膜処理の後段において、第２の逆浸透膜処理、ＵＶ処理、または、イオン交換処理のうちの少なくとも１つを行うことが好ましい。 In the water recovery method, it is preferable to carry out at least one of a second reverse osmosis membrane treatment, a UV treatment, or an ion exchange treatment after the reverse osmosis membrane treatment.
本発明は、尿素を含む被処理水について逆浸透膜処理を行い水回収する逆浸透膜処理手段を備える水回収装置であって、前記逆浸透膜処理の前処理として除濁膜処理、および担体である活性炭上に尿素分解菌を担持させた生物活性炭処理を順に行う除濁膜処理手段および生物活性炭処理手段と、前記除濁膜処理の前段において殺菌剤を添加する殺菌剤添加手段と、を備え、前記殺菌剤が、臭素系酸化剤とスルファミン酸化合物とを含む安定化次亜臭素酸組成物である、水回収装置である。 The present invention is a water recovery apparatus equipped with a reverse osmosis membrane treatment means for performing reverse osmosis membrane treatment on urea-containing water to be treated and recovering water, the water recovery apparatus comprising a turbidity removal membrane treatment means and a biological activated carbon treatment means for sequentially performing a turbidity removal membrane treatment as a pretreatment for the reverse osmosis membrane treatment and a biological activated carbon treatment in which urea-decomposing bacteria are supported on an activated carbon carrier, and a bactericide adding means for adding a bactericide in the stage prior to the turbidity removal membrane treatment , wherein the bactericide is a stabilized hypobromous acid composition containing a bromine-based oxidant and a sulfamic acid compound .
前記水回収装置において、前記殺菌剤添加手段は、前記除濁膜処理で得られる除濁膜処理水中の残留塩素濃度が０．０２～０．５ｍｇ－Ｃｌ２／Ｌの範囲となるように前記安定化次亜臭素酸組成物を添加することが好ましい。 In the water recovery apparatus, the disinfectant adding means preferably adds the stabilized hypobromous acid composition so that the residual chlorine concentration in the turbidity membrane treated water obtained by the turbidity membrane treatment is in the range of 0.02 to 0.5 mg-Cl 2 /L.
前記水回収装置において、前記被処理水が下水処理水であり、前記逆浸透膜処理の透過水を半導体工場の純水製造の原水として回収することが好ましい。 In the water recovery device, it is preferable that the water to be treated is sewage treatment water, and the permeate from the reverse osmosis membrane treatment is recovered as raw water for producing pure water in a semiconductor factory.
前記水回収装置において、前記逆浸透膜処理手段の後段に、第２の逆浸透膜処理手段、ＵＶ処理手段、または、イオン交換処理手段のうちの少なくとも１つを備えることが好ましい。 In the water recovery device, it is preferable to provide at least one of a second reverse osmosis membrane treatment means, a UV treatment means, or an ion exchange treatment means downstream of the reverse osmosis membrane treatment means.
本発明では、尿素を含む被処理水からの水回収において、除濁膜での生物等による閉塞を抑制することができ、かつ生物活性炭における閉塞を抑制し、尿素分解菌の生成を大きく抑制することなく、尿素の除去が可能である水回収方法および水回収装置を提供することができる。 The present invention provides a water recovery method and water recovery device that can prevent clogging of the turbidity membrane by organisms and the like when recovering water from treated water that contains urea, and can also prevent clogging of the biological activated carbon, thereby removing urea without significantly suppressing the production of urea-decomposing bacteria.
本発明の実施の形態について以下説明する。本実施形態は本発明を実施する一例であって、本発明は本実施形態に限定されるものではない。 The following describes an embodiment of the present invention. This embodiment is an example of implementing the present invention, and the present invention is not limited to this embodiment.
本発明の実施形態に係る水回収装置の一例の概略を図１に示し、その構成について説明する。 An example of a water recovery device according to an embodiment of the present invention is shown in FIG. 1, and its configuration will be described.
図１に示す水回収装置１は、尿素を含む被処理水について逆浸透膜処理を行い水回収する逆浸透膜処理手段として、逆浸透膜処理装置２０と、逆浸透膜処理装置２０の前処理として除濁膜処理および生物活性炭処理を順に行う除濁膜処理手段として除濁膜処理装置１２および生物活性炭処理手段として生物活性炭処理装置１６と、除濁膜処理の前段において殺菌剤を添加する殺菌剤添加手段として、殺菌剤添加配管５０と、を備える。水回収装置１は、被処理水を貯留する被処理水槽１０と、除濁膜処理で得られた除濁膜処理水を貯留する除濁膜処理水槽１４と、生物活性炭処理で得られた活性炭処理水を貯留する活性炭処理水槽１８と、を備えてもよい。 The water recovery device 1 shown in FIG. 1 includes a reverse osmosis membrane treatment device 20 as a reverse osmosis membrane treatment means for performing reverse osmosis membrane treatment on urea-containing water to recover water, a turbidity removal membrane treatment device 12 as a turbidity removal membrane treatment means for sequentially performing turbidity removal membrane treatment and biological activated carbon treatment as pretreatment for the reverse osmosis membrane treatment device 20, a biological activated carbon treatment device 16 as a biological activated carbon treatment means, and a bactericide addition pipe 50 as a bactericide addition means for adding a bactericide before the turbidity removal membrane treatment. The water recovery device 1 may include a treated water tank 10 for storing the water to be treated, a turbidity removal membrane treatment water tank 14 for storing the turbidity removal membrane treatment water obtained by the turbidity removal membrane treatment, and an activated carbon treatment water tank 18 for storing the activated carbon treatment water obtained by the biological activated carbon treatment.
水回収装置１において、被処理水槽１０の被処理水入口には、被処理水配管３０が接続されている。被処理水槽１０の出口と除濁膜処理装置１２の入口とは、ポンプ２２を介して被処理水配管３２により接続されている。除濁膜処理装置１２の二次側の出口と除濁膜処理水槽１４の入口とは、除濁膜処理水配管３４により接続されている。除濁膜処理水槽１４の除濁膜処理水出口と生物活性炭処理装置１６の入口とは、ポンプ２４を介して除濁膜処理水配管３６により接続されている。生物活性炭処理装置１６の出口と活性炭処理水槽１８の入口とは、活性炭処理水配管３８により接続されている。活性炭処理水槽１８の出口と逆浸透膜処理装置２０の入口とは、ポンプ２８を介して活性炭処理水配管４０により接続されている。逆浸透膜処理装置２０の透過水出口には、透過水配管４２が接続され、濃縮水出口には、濃縮水配管４４が接続されている。除濁膜処理水槽１４の逆洗水出口と除濁膜処理水配管３４の途中とは、ポンプ２６を介して逆洗水配管４６により接続されている。除濁膜処理装置１２の一次側の逆洗排水出口には、逆洗排水配管４８が接続されている。被処理水槽１０の殺菌剤入口には、殺菌剤添加配管５０が接続されている。 In the water recovery device 1, the treated water inlet of the treated water tank 10 is connected to the treated water pipe 30. The outlet of the treated water tank 10 and the inlet of the turbidity removal membrane treatment device 12 are connected by the treated water pipe 32 via the pump 22. The secondary side outlet of the turbidity removal membrane treatment device 12 and the inlet of the turbidity removal membrane treatment water tank 14 are connected by the turbidity removal membrane treatment water pipe 34. The turbidity removal membrane treatment water outlet of the turbidity removal membrane treatment water tank 14 and the inlet of the biological activated carbon treatment device 16 are connected by the turbidity removal membrane treatment water pipe 36 via the pump 24. The outlet of the biological activated carbon treatment device 16 and the inlet of the activated carbon treatment water tank 18 are connected by the activated carbon treatment water pipe 38. The outlet of the activated carbon treatment water tank 18 and the inlet of the reverse osmosis membrane treatment device 20 are connected by the activated carbon treatment water pipe 40 via the pump 28. The permeated water outlet of the reverse osmosis membrane treatment device 20 is connected to the permeated water pipe 42, and the concentrated water outlet is connected to the concentrated water pipe 44. The backwash water outlet of the turbidity removal membrane treatment tank 14 is connected to the middle of the turbidity removal membrane treatment water piping 34 by a backwash water piping 46 via a pump 26. A backwash drainage pipe 48 is connected to the backwash drainage outlet on the primary side of the turbidity removal membrane treatment device 12. A bactericide addition pipe 50 is connected to the bactericide inlet of the treated water tank 10.
本実施形態に係る水回収方法および水回収装置１の動作について説明する。 The water recovery method and operation of the water recovery device 1 according to this embodiment will be described.
尿素を含む被処理水は、被処理水配管３０を通して必要に応じて被処理水槽１０へ貯留される。被処理水槽１０において、被処理水へ殺菌剤添加配管５０を通して殺菌剤が添加される（殺菌剤添加工程）。殺菌剤が添加された被処理水は、ポンプ２２により被処理水配管３２を通して除濁膜処理装置１２へ送液される。除濁膜処理装置１２において、逆浸透膜処理の前処理として除濁膜処理が行われ、被処理水中の濁質等が除去される（除濁膜処理工程）。 The water to be treated, which contains urea, is stored in the water tank 10 as needed through the water pipe 30. In the water tank 10, a bactericide is added to the water to be treated through the bactericide addition pipe 50 (bactericide addition process). The water to be treated to which the bactericide has been added is pumped by the pump 22 through the water pipe 32 to the turbidity removal membrane treatment device 12. In the turbidity removal membrane treatment device 12, turbidity removal membrane treatment is performed as a pretreatment for the reverse osmosis membrane treatment, and turbid matter and the like in the water to be treated are removed (turbidity removal membrane treatment process).
殺菌剤は除濁膜処理の前段において添加されればよく、被処理水配管３０において添加されてもよいし、被処理水配管３２において添加されてもよい。 The bactericide may be added prior to the turbidity membrane treatment, and may be added in the treated water pipe 30 or in the treated water pipe 32.
除濁膜処理により得られた除濁膜処理水は、除濁膜処理水配管３４を通して必要に応じて除濁膜処理水槽１４へ貯留される。除濁膜処理水は、ポンプ２４により除濁膜処理水配管３６を通して生物活性炭処理装置１６へ送液される。生物活性炭処理装置１６において、逆浸透膜処理の前処理として生物活性炭処理が行われ、除濁膜処理水中の有機物、尿素等が除去され、有機物、尿素等の量が低減される（生物活性炭処理工程）。 The turbidity membrane treated water obtained by the turbidity membrane treatment is stored in the turbidity membrane treated water tank 14 as needed through the turbidity membrane treated water piping 34. The turbidity membrane treated water is pumped to the biological activated carbon treatment device 16 through the turbidity membrane treated water piping 36 by the pump 24. In the biological activated carbon treatment device 16, biological activated carbon treatment is performed as a pretreatment for the reverse osmosis membrane treatment, and organic matter, urea, etc. in the turbidity membrane treated water are removed, and the amount of organic matter, urea, etc. is reduced (biological activated carbon treatment process).
生物活性炭処理により得られた活性炭処理水は、活性炭処理水配管３８を通して必要に応じて活性炭処理水槽１８へ貯留される。活性炭処理水は、ポンプ２８により活性炭処理水配管４０を通して逆浸透膜処理装置２０へ送液される。逆浸透膜処理装置２０において、逆浸透膜処理が行われ、透過水と濃縮水とが得られる（逆浸透膜処理工程）。透過水は、透過水配管４２を通して排出され、例えば半導体工場の純水製造の原水として回収される。濃縮水は、濃縮水配管４４を通して排出される。 The activated carbon treated water obtained by the biological activated carbon treatment is stored in the activated carbon treated water tank 18 as needed through the activated carbon treated water piping 38. The activated carbon treated water is pumped by the pump 28 through the activated carbon treated water piping 40 to the reverse osmosis membrane treatment device 20. In the reverse osmosis membrane treatment device 20, reverse osmosis membrane treatment is performed, and permeated water and concentrated water are obtained (reverse osmosis membrane treatment process). The permeated water is discharged through the permeated water piping 42 and is recovered as raw water for pure water production in a semiconductor factory, for example. The concentrated water is discharged through the concentrated water piping 44.
除濁膜の洗浄が必要になった場合には、例えば、除濁膜処理水槽１４から除濁膜処理水が逆洗水としてポンプ２６により逆洗水配管４６、除濁膜処理水配管３４を通して除濁膜処理装置１２の二次側へ供給され、除濁膜の逆洗が行われる（逆洗工程）。逆洗排水は、除濁膜処理装置１２の一次側から逆洗排水配管４８を通して排出される。 When it becomes necessary to clean the turbidity removal membrane, for example, the turbidity removal membrane treated water is supplied as backwash water from the turbidity removal membrane treatment tank 14 by the pump 26 through the backwash water pipe 46 and the turbidity removal membrane treated water pipe 34 to the secondary side of the turbidity removal membrane treatment device 12, and the turbidity removal membrane is backwashed (backwash process). The backwash wastewater is discharged from the primary side of the turbidity removal membrane treatment device 12 through the backwash wastewater pipe 48.
本実施形態に係る水回収方法および水回収装置１では、下水二次処理水等の尿素を含む被処理水を除濁膜、生物活性炭、逆浸透膜の順で水回収する方法において、除濁膜処理の前段で殺菌剤を添加する。 In the water recovery method and water recovery device 1 according to this embodiment, in a method for recovering water containing urea, such as secondary sewage treatment water, in the order of turbidity removal membrane, biological activated carbon, and reverse osmosis membrane, a bactericide is added prior to the turbidity removal membrane treatment.
尿素を含む被処理水からの水回収において、逆浸透膜処理の前処理として除濁膜処理および生物活性炭処理を順に行い、除濁膜処理の前段で被処理水中に殺菌剤を添加することによって、除濁膜での生物等による閉塞を抑制することができ、かつ生物活性炭における閉塞を抑制し、尿素分解菌の生成を大きく抑制することなく、尿素の除去が可能であることがわかった。本方法によれば、ＲＯ透過水中の尿素濃度を低減することができ、回収水を純水原水に使用することも可能となり、工場の取水量の削減に大きく貢献することができる。 In recovering water from treated water that contains urea, it has been found that by carrying out turbidity removal membrane treatment and biological activated carbon treatment in that order as pretreatment for reverse osmosis membrane treatment, and adding a bactericide to the treated water prior to the turbidity removal membrane treatment, it is possible to prevent clogging of the turbidity removal membrane by organisms, and also to prevent clogging of the biological activated carbon, making it possible to remove urea without significantly suppressing the production of urea-decomposing bacteria. This method can reduce the urea concentration in the RO permeate, and also makes it possible to use the recovered water as pure raw water, making a significant contribution to reducing the amount of water intake from the factory.
殺菌剤としては、次亜塩素酸、クロロスルファミン酸（結合塩素剤）、次亜臭素酸、安定化次亜臭素酸組成物等のハロゲン系殺菌剤等が挙げられ、生物活性炭における尿素分解菌の生成、繁殖を抑制しにくい等の点から、安定化次亜臭素酸組成物が好ましい。 Examples of disinfectants include halogen-based disinfectants such as hypochlorous acid, chlorosulfamic acid (combined chlorine agent), hypobromous acid, and stabilized hypobromous acid compositions, and stabilized hypobromous acid compositions are preferred because they are less likely to inhibit the production and proliferation of urea-decomposing bacteria in biological activated carbon.
安定化次亜臭素酸組成物は、臭素系酸化剤とスルファミン酸化合物とを含むものである。「臭素系酸化剤とスルファミン酸化合物とを含む安定化次亜臭素酸組成物」は、「臭素系酸化剤」と「スルファミン酸化合物」との混合物を含む安定化次亜臭素酸組成物であってもよいし、「臭素系酸化剤とスルファミン酸化合物との反応生成物」を含む安定化次亜臭素酸組成物であってもよい。 The stabilized hypobromous acid composition contains a bromine-based oxidizing agent and a sulfamic acid compound. The "stabilized hypobromous acid composition containing a bromine-based oxidizing agent and a sulfamic acid compound" may be a stabilized hypobromous acid composition containing a mixture of a "bromine-based oxidizing agent" and a "sulfamic acid compound", or may be a stabilized hypobromous acid composition containing a "reaction product of a bromine-based oxidizing agent and a sulfamic acid compound".
すなわち、本実施形態に係る水回収方法では、除濁膜処理の前段において尿素を含む被処理水中に、例えば「臭素系酸化剤」と「スルファミン酸化合物」との混合物を添加する。これにより、被処理水中で、安定化次亜臭素酸組成物が生成すると考えられる。 That is, in the water recovery method according to this embodiment, a mixture of, for example, a "bromine-based oxidizing agent" and a "sulfamic acid compound" is added to the water to be treated that contains urea in the stage prior to the turbidity membrane treatment. This is thought to produce a stabilized hypobromous acid composition in the water to be treated.
また、本実施形態に係る水回収方法では、除濁膜処理の前段において尿素を含む被処理水中に、例えば「臭素系酸化剤とスルファミン酸化合物との反応生成物」である安定化次亜臭素酸組成物を添加する。 In addition, in the water recovery method according to this embodiment, a stabilized hypobromous acid composition, which is, for example, a "reaction product between a bromine-based oxidizing agent and a sulfamic acid compound," is added to the urea-containing water to be treated prior to the turbidity membrane treatment.
具体的には本実施形態に係る水回収方法では、除濁膜処理の前段において尿素を含む被処理水中に、例えば、「臭素」、「塩化臭素」、「次亜臭素酸」または「臭化ナトリウムと次亜塩素酸との反応物」と、「スルファミン酸化合物」との混合物を添加する。 Specifically, in the water recovery method according to this embodiment, a mixture of, for example, "bromine," "bromine chloride," "hypobromous acid" or "a reaction product of sodium bromide and hypochlorous acid" and a "sulfamic acid compound" is added to the urea-containing water to be treated in the stage prior to the turbidity membrane treatment.
また、本実施形態に係る水回収方法では、除濁膜処理の前段において尿素を含む被処理水中に、例えば、「臭素とスルファミン酸化合物との反応生成物」、「塩化臭素とスルファミン酸化合物との反応生成物」、「次亜臭素酸とスルファミン酸化合物との反応生成物」、または「臭化ナトリウムと次亜塩素酸との反応物と、スルファミン酸化合物と、の反応生成物」である安定化次亜臭素酸組成物を添加する。 In the water recovery method according to this embodiment, a stabilized hypobromous acid composition, which is, for example, a "reaction product of bromine and a sulfamic acid compound," a "reaction product of bromine chloride and a sulfamic acid compound," a "reaction product of hypobromous acid and a sulfamic acid compound," or a "reaction product of sodium bromide, hypochlorous acid, and a sulfamic acid compound," is added to the urea-containing water to be treated in the preliminary stage of the turbidity removal membrane treatment.
安定化次亜臭素酸組成物は次亜塩素酸等の塩素系酸化剤等の殺菌剤と同等以上の殺菌効果を発揮するにも関わらず、塩素系酸化剤等の殺菌剤と比較すると、尿素分解菌の生成を大きく抑制することなく、除濁膜、逆浸透膜への劣化影響も低いため、除濁膜、逆浸透膜でのファウリングを抑制しながら、除濁膜、逆浸透膜の酸化劣化を抑制できる。このため、本実施形態に係る水回収方法で用いられる安定化次亜臭素酸組成物は、除濁膜処理、生物活性炭処理、逆浸透膜処理の順で処理を行う水回収で用いる殺菌剤としては好適である。 Although the stabilized hypobromous acid composition exerts a bactericidal effect equal to or greater than that of bactericides such as chlorine-based oxidizing agents, such as hypochlorous acid, it does not significantly suppress the production of urea-decomposing bacteria and has a low degradation effect on the turbidity removal membrane and reverse osmosis membrane compared to bactericides such as chlorine-based oxidizing agents, so that it can suppress oxidative deterioration of the turbidity removal membrane and reverse osmosis membrane while suppressing fouling in the turbidity removal membrane and reverse osmosis membrane. For this reason, the stabilized hypobromous acid composition used in the water recovery method according to this embodiment is suitable as a bactericide to be used in water recovery in which treatment is performed in the order of turbidity removal membrane treatment, biological activated carbon treatment, and reverse osmosis membrane treatment.
本実施形態に係る水回収方法のうち、「臭素系酸化剤」が、臭素である場合、塩素系酸化剤が存在しないため、除濁膜、逆浸透膜への劣化影響が著しく低い。 In the water recovery method according to this embodiment, when the "bromine-based oxidizing agent" is bromine, there is no chlorine-based oxidizing agent present, so the degradation effect on the turbidity removal membrane and reverse osmosis membrane is significantly low.
本実施形態に係る水回収方法では、除濁膜処理の前段において尿素を含む被処理水中に、例えば、「臭素系酸化剤」と「スルファミン酸化合物」とを薬注ポンプ等により注入すればよい。「臭素系酸化剤」と「スルファミン酸化合物」とは別々に被処理水に添加してもよく、または、原液同士で混合させてから被処理水に添加してもよい。 In the water recovery method according to this embodiment, for example, a "bromine-based oxidizing agent" and a "sulfamic acid compound" are injected into the water to be treated containing urea in the stage prior to the turbidity membrane treatment using a chemical injection pump or the like. The "bromine-based oxidizing agent" and the "sulfamic acid compound" may be added separately to the water to be treated, or the raw solutions may be mixed together and then added to the water to be treated.
また、除濁膜処理の前段において尿素を含む被処理水中に、例えば、「臭素系酸化剤とスルファミン酸化合物との反応生成物」を薬注ポンプ等により注入してもよい。 In addition, for example, a "reaction product of a bromine-based oxidizing agent and a sulfamic acid compound" may be injected into the urea-containing water to be treated in the preliminary stage of the turbidity removal membrane treatment using a chemical injection pump or the like.
安定化次亜臭素酸組成物において、「臭素系酸化剤」の当量に対する「スルファミン酸化合物」の当量の比は、１以上であることが好ましく、１以上２以下の範囲であることがより好ましい。「臭素系酸化剤」の当量に対する「スルファミン酸化合物」の当量の比が１未満であると、除濁膜、逆浸透膜を劣化させる可能性があり、２を超えると、製造コストが増加する場合がある。 In the stabilized hypobromous acid composition, the ratio of the equivalents of the "sulfamic acid compound" to the equivalents of the "bromine-based oxidizing agent" is preferably 1 or more, and more preferably in the range of 1 to 2. If the ratio of the equivalents of the "sulfamic acid compound" to the equivalents of the "bromine-based oxidizing agent" is less than 1, it may cause deterioration of the turbidity removal membrane and reverse osmosis membrane, and if it exceeds 2, the production cost may increase.
これらのうち、臭素を用いた「臭素とスルファミン酸化合物（臭素とスルファミン酸化合物の混合物）」または「臭素とスルファミン酸化合物との反応生成物」の酸化剤は、「次亜塩素酸と臭素化合物とスルファミン酸」の酸化剤および「塩化臭素とスルファミン酸」の酸化剤等に比べて、臭素酸の副生が少なく、酸化剤としてはより好ましい。 Of these, oxidizing agents using bromine, such as "bromine and sulfamic acid compounds (mixtures of bromine and sulfamic acid compounds)" or "reaction products of bromine and sulfamic acid compounds," produce less bromic acid as a by-product and are more preferable as oxidizing agents than oxidizing agents using "hypochlorous acid, bromine compounds, and sulfamic acid" and oxidizing agents using "bromine chloride and sulfamic acid."
臭素系酸化剤としては、臭素（液体臭素）、塩化臭素、臭素酸、臭素酸塩、次亜臭素酸等が挙げられる。次亜臭素酸は、臭化ナトリウム等の臭素化合物と次亜塩素酸等の塩素系酸化剤とを反応させて生成させたものであってもよい。 Bromine-based oxidizing agents include bromine (liquid bromine), bromine chloride, bromic acid, bromates, hypobromous acid, etc. Hypobromous acid may be produced by reacting a bromine compound such as sodium bromide with a chlorine-based oxidizing agent such as hypochlorous acid.
臭素化合物としては、臭化ナトリウム、臭化カリウム、臭化リチウム、臭化アンモニウムおよび臭化水素酸等が挙げられる。これらのうち、製剤コスト等の点から、臭化ナトリウムが好ましい。 Bromine compounds include sodium bromide, potassium bromide, lithium bromide, ammonium bromide, and hydrobromic acid. Of these, sodium bromide is preferred from the standpoint of formulation costs, etc.
スルファミン酸化合物は、以下の一般式（１）で示される化合物である。
Ｒ２ＮＳＯ３Ｈ （１）
（式中、Ｒは独立して水素原子または炭素数１～８のアルキル基である。）
The sulfamic acid compound is a compound represented by the following general formula (1).
R2NSO3H ( 1 )
(In the formula, R is independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)
スルファミン酸化合物としては、例えば、２個のＲ基の両方が水素原子であるスルファミン酸（アミド硫酸）の他に、Ｎ－メチルスルファミン酸、Ｎ－エチルスルファミン酸、Ｎ－プロピルスルファミン酸、Ｎ－イソプロピルスルファミン酸、Ｎ－ブチルスルファミン酸等の２個のＲ基の一方が水素原子であり、他方が炭素数１～８のアルキル基であるスルファミン酸化合物、Ｎ，Ｎ－ジメチルスルファミン酸、Ｎ，Ｎ－ジエチルスルファミン酸、Ｎ，Ｎ－ジプロピルスルファミン酸、Ｎ，Ｎ－ジブチルスルファミン酸、Ｎ－メチル－Ｎ－エチルスルファミン酸、Ｎ－メチル－Ｎ－プロピルスルファミン酸等の２個のＲ基の両方が炭素数１～８のアルキル基であるスルファミン酸化合物、Ｎ－フェニルスルファミン酸等の２個のＲ基の一方が水素原子であり、他方が炭素数６～１０のアリール基であるスルファミン酸化合物、またはこれらの塩等が挙げられる。スルファミン酸塩としては、例えば、ナトリウム塩、カリウム塩等のアルカリ金属塩、カルシウム塩、ストロンチウム塩、バリウム塩等のアルカリ土類金属塩、マンガン塩、銅塩、亜鉛塩、鉄塩、コバルト塩、ニッケル塩等の他の金属塩、アンモニウム塩およびグアニジン塩等が挙げられる。スルファミン酸化合物およびこれらの塩は、１種を単独で用いても、２種以上を組み合わせて用いてもよい。スルファミン酸化合物としては、環境負荷等の点から、スルファミン酸（アミド硫酸）を用いるのが好ましい。 Examples of sulfamic acid compounds include sulfamic acid (amidosulfuric acid) in which both R groups are hydrogen atoms, as well as sulfamic acid compounds in which one of the R groups is a hydrogen atom and the other is an alkyl group having 1 to 8 carbon atoms, such as N-methylsulfamic acid, N-ethylsulfamic acid, N-propylsulfamic acid, N-isopropylsulfamic acid, and N-butylsulfamic acid, sulfamic acid compounds in which both of the R groups are alkyl groups having 1 to 8 carbon atoms, such as N,N-dimethylsulfamic acid, N,N-diethylsulfamic acid, N,N-dipropylsulfamic acid, N,N-dibutylsulfamic acid, N-methyl-N-ethylsulfamic acid, and N-methyl-N-propylsulfamic acid, sulfamic acid compounds in which one of the R groups is a hydrogen atom and the other is an aryl group having 6 to 10 carbon atoms, such as N-phenylsulfamic acid, and salts thereof. Examples of sulfamic acid salts include alkali metal salts such as sodium salts and potassium salts, alkaline earth metal salts such as calcium salts, strontium salts and barium salts, other metal salts such as manganese salts, copper salts, zinc salts, iron salts, cobalt salts and nickel salts, ammonium salts and guanidine salts. Sulfamic acid compounds and their salts may be used alone or in combination of two or more. As the sulfamic acid compound, it is preferable to use sulfamic acid (amidosulfuric acid) from the viewpoint of environmental load, etc.
除濁膜での生物の繁殖を十分に抑制するためには、除濁膜処理で得られる除濁膜処理水中の残留塩素濃度が０．０２～０．５ｍｇ／Ｌの範囲となるように安定化次亜臭素酸組成物を添加することが好ましく、０．０５～０．５ｍｇ－Ｃｌ２／Ｌの範囲となるように安定化次亜臭素酸組成物を添加することがより好ましく、０．２～０．３ｍｇ－Ｃｌ２／Ｌの範囲となるように安定化次亜臭素酸組成物を添加することがさらに好ましい。除濁膜処理水中の残留塩素濃度が０．０２ｍｇ／Ｌ未満であると、除濁膜での生物等による閉塞を抑制できない場合があり、０．５ｍｇ／Ｌを超えると、生物活性炭における尿素分解菌の生成、繁殖が抑制される場合がある。 In order to sufficiently suppress the proliferation of organisms in the turbidity removal membrane, it is preferable to add the stabilized hypobromous acid composition so that the residual chlorine concentration in the turbidity removal membrane treated water obtained by the turbidity removal membrane treatment is in the range of 0.02 to 0.5 mg/L, more preferably 0.05 to 0.5 mg-Cl 2 /L, and even more preferably 0.2 to 0.3 mg-Cl 2 /L. If the residual chlorine concentration in the turbidity removal membrane treated water is less than 0.02 mg/L, clogging of the turbidity removal membrane by organisms may not be suppressed, and if it exceeds 0.5 mg/L, the production and proliferation of urea decomposition bacteria in the biological activated carbon may be suppressed.
また、副次的な効果として、被処理水中にアンモニアが含まれている場合には、通常はアンモニアに次亜塩素酸が消費されて除濁膜の閉塞抑制を十分に行うことができない場合があるが、安定化次亜臭素酸組成物を用いると、被処理水中にアンモニアが含まれている場合でも除濁膜の閉塞を抑制することができるという効果が得られる。また、除濁膜処理水中の残留塩素濃度の調整も容易である。 As a secondary effect, when ammonia is contained in the water to be treated, hypochlorous acid is usually consumed by the ammonia, and clogging of the turbidity removal membrane may not be sufficiently suppressed. However, by using a stabilized hypobromous acid composition, it is possible to suppress clogging of the turbidity removal membrane even when ammonia is contained in the water to be treated. In addition, it is easy to adjust the residual chlorine concentration in the turbidity removal membrane-treated water.
下水処理場の水温は比較的高く維持されており、通常は被処理水の加温を行わなくてもよいが、冬季に水温が低下すると尿素分解菌の活性が低下するため、被処理水の加温によって２０℃以上、好ましくは２５℃以上を保つように調整するとよりよい。 The water temperature in sewage treatment plants is kept relatively high, and it is usually not necessary to heat the water being treated. However, as the water temperature drops in winter, the activity of urea-decomposing bacteria decreases, so it is better to adjust the temperature of the water being treated to 20°C or higher, and preferably 25°C or higher.
除濁膜処理の前段において、尿素を含む被処理水中に、安定化次亜臭素酸組成物にさらにアルカリを存在させてもよい。アルカリとしては、水酸化ナトリウム、水酸化カリウム等の水酸化アルカリ等が挙げられる。低温の製品安定性等の点から、水酸化ナトリウムと水酸化カリウムとを併用してもよい。また、アルカリは、固形でなく、水溶液として用いてもよい。 In the preliminary stage of the turbidity removal membrane treatment, an alkali may be added to the stabilized hypobromous acid composition in the urea-containing water to be treated. Examples of the alkali include alkali hydroxides such as sodium hydroxide and potassium hydroxide. From the viewpoint of product stability at low temperatures, sodium hydroxide and potassium hydroxide may be used in combination. The alkali may be used as an aqueous solution rather than as a solid.
本実施形態に係る水回収方法は、逆浸透膜として昨今主流であるポリアミド系高分子膜に好適に適用することができる。ポリアミド系高分子膜は、酸化剤に対する耐性が比較的低く、遊離塩素等をポリアミド系高分子膜に連続的に接触させると、膜性能の著しい低下が起こる場合がある。しかしながら、酸化剤として安定化次亜臭素酸組成物を用いると、ポリアミド高分子膜においても、このような著しい膜性能の低下はほとんど起こらない。 The water recovery method according to this embodiment can be suitably applied to polyamide polymer membranes, which are currently the mainstream reverse osmosis membranes. Polyamide polymer membranes have relatively low resistance to oxidizing agents, and continuous contact with free chlorine or the like can cause a significant decrease in membrane performance. However, when a stabilized hypobromous acid composition is used as the oxidizing agent, such a significant decrease in membrane performance hardly occurs, even in polyamide polymer membranes.
被処理水としては、尿素を含む水であればよく、特に制限はないが、例えば、下水処理水、地下水、河川水等が挙げられる。逆浸透膜処理の透過水を、例えば、半導体工場の純水製造の原水、設備用水、スクラバー用水として回収することができる。被処理水が下水処理水であり、逆浸透膜処理の透過水を半導体工場の純水製造の原水として回収することが好ましい。 The water to be treated may be any water containing urea, and is not particularly limited; examples include treated sewage water, groundwater, and river water. The permeate from the reverse osmosis membrane treatment can be recovered, for example, as raw water for pure water production in semiconductor factories, water for equipment use, and water for scrubbers. It is preferable that the water to be treated is treated sewage water, and that the permeate from the reverse osmosis membrane treatment is recovered as raw water for pure water production in semiconductor factories.
被処理水中の尿素の含有量は、例えば、１０～１００μｇ／Ｌの範囲であり、好ましくは１０～５０ｍｇ／Ｌの範囲である。 The urea content in the treated water is, for example, in the range of 10 to 100 μg/L, and preferably in the range of 10 to 50 mg/L.
被処理水のＴＯＣは、例えば、１～１００ｍｇ／Ｌの範囲であり、好ましくは１～２０ｍｇ／Ｌの範囲である。 The TOC of the treated water is, for example, in the range of 1 to 100 mg/L, and preferably in the range of 1 to 20 mg/L.
被処理水はさらにアンモニアを含んでもよく、被処理水中のアンモニアの含有量は、例えば、１～１００ｍｇ／Ｌの範囲であり、好ましくは１～５０ｍｇ／Ｌの範囲である。殺菌剤として次亜塩素酸や結合塩素剤を用いると、被処理水がアンモニアを含む場合に次亜塩素酸や結合塩素剤が分解されてしまう場合があるが、安定化次亜臭素酸組成物は、被処理水がアンモニアを含んでいてもほとんど分解されない。 The water to be treated may further contain ammonia, and the ammonia content in the water to be treated is, for example, in the range of 1 to 100 mg/L, and preferably in the range of 1 to 50 mg/L. When hypochlorous acid or combined chlorine agents are used as disinfectants, the hypochlorous acid or combined chlorine agent may be decomposed if the water to be treated contains ammonia, but the stabilized hypobromous acid composition is hardly decomposed even if the water to be treated contains ammonia.
本実施形態に係る水回収方法および水回収装置によって、処理水（ＲＯ透過水）中の尿素の含有量を、例えば、５０μｇ／Ｌ以下、好ましくは１０μｇ／Ｌ以下とすることができる。 The water recovery method and water recovery device according to this embodiment can reduce the urea content in the treated water (RO permeate) to, for example, 50 μg/L or less, preferably 10 μg/L or less.
本実施形態に係る水回収方法および水回収装置によって、処理水（ＲＯ透過水）中のＴＯＣを、例えば、１０μｇ／Ｌ以下、好ましくは２μｇ／Ｌ以下とすることができる。 The water recovery method and water recovery device according to this embodiment can reduce the TOC in the treated water (RO permeate) to, for example, 10 μg/L or less, preferably 2 μg/L or less.
被処理水のｐＨは、例えば、２～１２の範囲であり、４～１１の範囲であることが好ましい。被処理水のｐＨの下限は、５．５以上であることが好ましく、６．５以上であることがより好ましく、７．０以上であることがさらに好ましい。被処理水のｐＨの上限は、９．０以下であることが好ましく、８．０以下であることがより好ましい。被処理水のｐＨが５．５以上である場合に、本実施形態に係る水回収方法を好適に適用することができる。 The pH of the water to be treated is, for example, in the range of 2 to 12, and preferably in the range of 4 to 11. The lower limit of the pH of the water to be treated is preferably 5.5 or more, more preferably 6.5 or more, and even more preferably 7.0 or more. The upper limit of the pH of the water to be treated is preferably 9.0 or less, and more preferably 8.0 or less. When the pH of the water to be treated is 5.5 or more, the water recovery method according to this embodiment can be suitably applied.
除濁膜処理で用いられる除濁膜は、精密ろ過膜（ＭＦ膜）または限外ろ過膜（ＵＦ膜）である。限外ろ過膜の公称孔径は、０．０１μｍ以上、０．１μｍ未満であり、精密ろ過膜の孔径は、０．１μｍ以上、１０μｍ以下である。分画分子量で表すと、限外ろ過膜の分画分子量は、１，０００以上、１，０００，０００未満である。除濁膜は、平膜タイプでも中空糸タイプであってもよい。 The turbidity removal membrane used in the turbidity removal membrane treatment is a microfiltration membrane (MF membrane) or an ultrafiltration membrane (UF membrane). The nominal pore size of the ultrafiltration membrane is 0.01 μm or more and less than 0.1 μm, and the pore size of the microfiltration membrane is 0.1 μm or more and 10 μm or less. In terms of molecular weight cutoff, the molecular weight cutoff of the ultrafiltration membrane is 1,000 or more and less than 1,000,000. The turbidity removal membrane may be a flat membrane type or a hollow fiber type.
生物活性炭処理で用いられる生物活性炭は、担体である活性炭上に尿素分解菌を担持させたものである。活性炭としては、例えば、粒状活性炭、粉状活性炭等が挙げられ、経済性、操作性等の点から粒状活性炭を用いることが好ましい。例えば、粒状活性炭に尿素を含む水を接触させることによって粒状活性炭上に尿素分解菌を担持させて粒状生物活性炭として用いればよい。生物活性炭処理工程では、例えば、粒状生物活性炭が充填された充填塔に上向流または下向流で除濁膜処理水を通水させればよい。 The biological activated carbon used in the biological activated carbon treatment is a carrier of activated carbon on which urea-decomposing bacteria are supported. Examples of activated carbon include granular activated carbon and powdered activated carbon, and it is preferable to use granular activated carbon from the standpoint of economy, ease of operation, and the like. For example, the granular activated carbon can be brought into contact with water containing urea to support urea-decomposing bacteria on the granular activated carbon, which can then be used as granular biological activated carbon. In the biological activated carbon treatment process, for example, turbidity membrane treated water can be passed through a packed tower filled with granular biological activated carbon in an upward or downward flow.
水道設備等に主に使われる粒状活性炭は、有効径（１０％通過径）が０．３～１．３ｍｍ、均等係数１．２～２．０である活性炭である。粒状活性炭としては、例えば、オルビーズＱＨＧ（オルガノ株式会社製）等を用いることができる。 Granular activated carbon, which is mainly used in water facilities, etc., is activated carbon with an effective diameter (10% passing diameter) of 0.3 to 1.3 mm and a uniformity coefficient of 1.2 to 2.0. For example, Orbeez QHG (manufactured by Organo Corporation) can be used as granular activated carbon.
逆浸透膜処理の後段において、第２の逆浸透膜処理装置、ＵＶ処理装置、または、イオン交換処理装置のうち少なくとも１つを備え、逆浸透膜処理の透過水について第２の逆浸透膜処理、ＵＶ処理、または、イオン交換処理のうち少なくとも１つの処理を行ってもよい。 At a stage subsequent to the reverse osmosis membrane treatment, at least one of a second reverse osmosis membrane treatment device, a UV treatment device, or an ion exchange treatment device may be provided, and at least one of a second reverse osmosis membrane treatment, a UV treatment, or an ion exchange treatment may be performed on the permeate from the reverse osmosis membrane treatment.
本実施形態に係る水回収方法において、被処理水のｐＨ５．５以上でスケールが発生する場合には、スケール抑制のために分散剤を上記安定化次亜臭素酸組成物と併用してもよい。分散剤としては、例えば、ポリアクリル酸、ポリマレイン酸、ホスホン酸等が挙げられる。分散剤の被処理水への添加量は、例えば、ＲＯ濃縮水中の濃度として０．１～１，０００ｍｇ／Ｌの範囲である。 In the water recovery method according to this embodiment, if scale occurs when the pH of the water to be treated is 5.5 or higher, a dispersant may be used in combination with the stabilized hypobromous acid composition to inhibit scale. Examples of dispersants include polyacrylic acid, polymaleic acid, and phosphonic acid. The amount of dispersant added to the water to be treated is, for example, in the range of 0.1 to 1,000 mg/L as the concentration in the RO concentrated water.
また、分散剤を使用せずにスケールの発生を抑制するためには、例えば、ＲＯ濃縮水中のシリカ濃度を溶解度以下に、カルシウムスケールの指標であるランゲリア指数を０以下になるように、逆浸透膜処理の回収率、水温、ｐＨ等の運転条件を調整することが挙げられる。 In addition, in order to suppress the formation of scale without using a dispersant, for example, the operating conditions of the reverse osmosis membrane treatment, such as the recovery rate, water temperature, and pH, can be adjusted so that the silica concentration in the RO concentrated water is below the solubility and the Langelier index, which is an indicator of calcium scale, is below 0.
＜安定化次亜臭素酸組成物＞
本実施形態に係る水回収方法で用いられる安定化次亜臭素酸組成物は、「臭素系酸化剤」と「スルファミン酸化合物」とを含有するものであり、さらにアルカリを含有してもよい。
<Stabilized hypobromous acid composition>
The stabilized hypobromous acid composition used in the water recovery method according to the present embodiment contains a "bromine-based oxidizing agent" and a "sulfamic acid compound", and may further contain an alkali.
また、本実施形態に係る水回収方法で用いられる安定化次亜臭素酸組成物は、「臭素系酸化剤とスルファミン酸化合物との反応生成物」を含有するものであり、さらにアルカリを含有してもよい。 The stabilized hypobromous acid composition used in the water recovery method according to this embodiment contains a "reaction product of a bromine-based oxidizing agent and a sulfamic acid compound" and may further contain an alkali.
臭素系酸化剤、臭素化合物、塩素系酸化剤およびスルファミン酸化合物については、上述した通りである。 Bromine-based oxidizing agents, bromine compounds, chlorine-based oxidizing agents, and sulfamic acid compounds are as described above.
本実施形態に係る安定化次亜臭素酸組成物としては、除濁膜や、ポリアミド系等の逆浸透膜をより劣化させず、ＲＯ透過水への有効ハロゲンのリーク量がより少ないため、臭素と、スルファミン酸化合物とを含有するもの（臭素とスルファミン酸化合物の混合物を含有するもの）、例えば、臭素とスルファミン酸化合物とアルカリと水との混合物、または、臭素とスルファミン酸化合物との反応生成物を含有するもの、例えば、臭素とスルファミン酸化合物との反応生成物と、アルカリと、水との混合物が好ましい。 As the stabilized hypobromous acid composition according to this embodiment, one containing bromine and a sulfamic acid compound (one containing a mixture of bromine and a sulfamic acid compound), for example, a mixture of bromine, a sulfamic acid compound, an alkali, and water, or one containing a reaction product of bromine and a sulfamic acid compound, for example, a mixture of a reaction product of bromine and a sulfamic acid compound, an alkali, and water, is preferred, since it does not deteriorate turbidity membranes or reverse osmosis membranes such as polyamide-based membranes and causes less leakage of effective halogen into the RO permeate.
本実施形態に係る安定化次亜臭素酸組成物、特に臭素とスルファミン酸化合物とを含む安定化次亜臭素酸組成物は、次亜塩素酸等の塩素系酸化剤と比較すると、ポリアミド系等の逆浸透膜の殺菌効果を有しながらも、次亜塩素酸等の塩素系酸化剤のような著しい膜劣化をほとんど引き起こすことがない。通常の使用濃度では、膜劣化への影響は実質的に無視することができる。このため、除濁膜処理、生物活性炭処理、ポリアミド系高分子膜等を用いる逆浸透膜処理の順で処理を行う水回収で用いる殺菌剤としては最適である。 The stabilized hypobromous acid composition according to this embodiment, particularly the stabilized hypobromous acid composition containing bromine and a sulfamic acid compound, has a bactericidal effect on polyamide-based reverse osmosis membranes compared to chlorine-based oxidizing agents such as hypochlorous acid, but hardly causes significant membrane deterioration like chlorine-based oxidizing agents such as hypochlorous acid. At normal usage concentrations, the effect on membrane deterioration can be practically ignored. For this reason, it is ideal as a bactericide to be used in water recovery, where treatment is performed in the order of turbidity removal membrane treatment, biological activated carbon treatment, and reverse osmosis membrane treatment using a polyamide-based polymer membrane, etc.
本実施形態に係る安定化次亜臭素酸組成物は、次亜塩素酸等の塩素系酸化剤等とは異なり、逆浸透膜をほとんど透過しないため、処理水水質への影響がほとんどない。また、次亜塩素酸等と同様に現場で濃度を測定することができるため、より正確な濃度管理が可能である。 Unlike chlorine-based oxidizing agents such as hypochlorous acid, the stabilized hypobromous acid composition according to this embodiment hardly permeates reverse osmosis membranes, and therefore has almost no effect on the quality of treated water. In addition, the concentration can be measured on-site in the same way as hypochlorous acid, allowing for more accurate concentration management.
安定化次亜臭素酸組成物のｐＨは、例えば、１３．０超であり、１３．２超であることがより好ましい。安定化次亜臭素酸組成物のｐＨが１３．０以下であると安定化次亜臭素酸組成物中の有効ハロゲンが不安定になる場合がある。 The pH of the stabilized hypobromous acid composition is, for example, greater than 13.0, and more preferably greater than 13.2. If the pH of the stabilized hypobromous acid composition is 13.0 or less, the available halogen in the stabilized hypobromous acid composition may become unstable.
安定化次亜臭素酸組成物中の臭素酸濃度は、５ｍｇ／ｋｇ未満であることが好ましい。安定化次亜臭素酸組成物中の臭素酸濃度が５ｍｇ／ｋｇ以上であると、ＲＯ透過水等の臭素酸イオンの濃度が高くなる場合がある。 The bromate concentration in the stabilized hypobromous acid composition is preferably less than 5 mg/kg. If the bromate concentration in the stabilized hypobromous acid composition is 5 mg/kg or more, the concentration of bromate ions in the RO permeate, etc. may become high.
＜安定化次亜臭素酸組成物の製造方法＞
本実施形態に係る水回収方法で用いられる安定化次亜臭素酸組成物は、臭素系酸化剤とスルファミン酸化合物とを混合することにより得られ、さらにアルカリを混合してもよい。
<Method of producing stabilized hypobromous acid composition>
The stabilized hypobromous acid composition used in the water recovery method according to the present embodiment is obtained by mixing a bromine-based oxidizing agent with a sulfamic acid compound, and may further include an alkali.
臭素とスルファミン酸化合物とを含む安定化次亜臭素酸組成物の製造方法としては、水、アルカリおよびスルファミン酸化合物を含む混合液に臭素を不活性ガス雰囲気下で添加して反応させる工程、または、水、アルカリおよびスルファミン酸化合物を含む混合液に臭素を不活性ガス雰囲気下で添加する工程を含むことが好ましい。不活性ガス雰囲気下で添加して反応させる、または、不活性ガス雰囲気下で添加することにより、安定化次亜臭素酸組成物中の臭素酸イオン濃度が低くなり、ＲＯ透過水等中の臭素酸イオン濃度が低くなる。 The method for producing a stabilized hypobromous acid composition containing bromine and a sulfamic acid compound preferably includes a step of adding bromine to a mixed solution containing water, an alkali, and a sulfamic acid compound under an inert gas atmosphere to cause a reaction, or a step of adding bromine to a mixed solution containing water, an alkali, and a sulfamic acid compound under an inert gas atmosphere. By adding and reacting under an inert gas atmosphere or by adding under an inert gas atmosphere, the bromate ion concentration in the stabilized hypobromous acid composition is reduced, and the bromate ion concentration in the RO permeate water, etc. is reduced.
用いる不活性ガスとしては限定されないが、製造等の面から窒素およびアルゴンのうち少なくとも１つが好ましく、特に製造コスト等の面から窒素が好ましい。 There are no limitations on the inert gas used, but from the standpoint of production etc., at least one of nitrogen and argon is preferred, and from the standpoint of production costs etc., nitrogen is particularly preferred.
臭素の添加の際の反応器内の酸素濃度は６％以下が好ましいが、４％以下がより好ましく、２％以下がさらに好ましく、１％以下が特に好ましい。臭素の反応の際の反応器内の酸素濃度が６％を超えると、反応系内の臭素酸の生成量が増加する場合がある。 The oxygen concentration in the reactor during the addition of bromine is preferably 6% or less, more preferably 4% or less, even more preferably 2% or less, and particularly preferably 1% or less. If the oxygen concentration in the reactor during the reaction of bromine exceeds 6%, the amount of bromic acid produced in the reaction system may increase.
臭素の添加率は、安定化次亜臭素酸組成物全体の量に対して２５重量％以下であることが好ましく、１重量％以上２０重量％以下であることがより好ましい。臭素の添加率が安定化次亜臭素酸組成物全体の量に対して２５重量％を超えると、反応系内の臭素酸の生成量が増加する場合がある。１重量％未満であると、殺菌力が劣る場合がある。 The addition rate of bromine is preferably 25% by weight or less, more preferably 1% by weight or more and 20% by weight or less, based on the total amount of the stabilized hypobromous acid composition. If the addition rate of bromine exceeds 25% by weight based on the total amount of the stabilized hypobromous acid composition, the amount of bromic acid produced in the reaction system may increase. If it is less than 1% by weight, the bactericidal power may be inferior.
臭素添加の際の反応温度は、０℃以上２５℃以下の範囲に制御することが好ましいが、製造コスト等の面から、０℃以上１５℃以下の範囲に制御することがより好ましい。臭素添加の際の反応温度が２５℃を超えると、反応系内の臭素酸の生成量が増加する場合があり、０℃未満であると、凍結する場合がある。 The reaction temperature when adding bromine is preferably controlled in the range of 0°C to 25°C, but from the viewpoint of production costs, it is more preferable to control it in the range of 0°C to 15°C. If the reaction temperature when adding bromine exceeds 25°C, the amount of bromic acid produced in the reaction system may increase, and if it is below 0°C, freezing may occur.
以下、実施例および比較例を挙げ、本発明をより具体的に詳細に説明するが、本発明は、以下の実施例に限定されるものではない。 The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.
［安定化次亜臭素酸組成物の調製］
窒素雰囲気下で、液体臭素：１６．９重量％（ｗｔ％）、スルファミン酸：１０．７重量％、水酸化ナトリウム：１２．９重量％、水酸化カリウム：３．９４重量％、水：残分を混合して、安定化次亜臭素酸組成物を調製した。安定化次亜臭素酸組成物のｐＨは１４、全塩素濃度は７．５重量％であった。全塩素濃度は、ＨＡＣＨ社の多項目水質分析計ＤＲ／４０００を用いて、全塩素測定法（ＤＰＤ（ジエチル－ｐ－フェニレンジアミン）法）により測定した値（ｍｇ－Ｃｌ２／Ｌ）である。安定化次亜臭素酸組成物の詳細な調製方法は以下の通りである。
[Preparation of stabilized hypobromous acid composition]
A stabilized hypobromous acid composition was prepared by mixing 16.9% by weight (wt%) of liquid bromine, 10.7% by weight of sulfamic acid, 12.9% by weight of sodium hydroxide, 3.94% by weight of potassium hydroxide, and the remainder of water under a nitrogen atmosphere. The pH of the stabilized hypobromous acid composition was 14, and the total chlorine concentration was 7.5% by weight. The total chlorine concentration was a value (mg-Cl 2 /L) measured by a total chlorine measurement method (DPD (diethyl-p-phenylenediamine) method) using a HACH multi-item water quality analyzer DR/4000. The detailed preparation method of the stabilized hypobromous acid composition is as follows.
反応容器内の酸素濃度が１％に維持されるように、窒素ガスの流量をマスフローコントローラでコントロールしながら連続注入で封入した２Ｌの４つ口フラスコに１４３６ｇの水、３６１ｇの水酸化ナトリウムを加え混合し、次いで３００ｇのスルファミン酸を加え混合した後、反応液の温度が０～１５℃になるように冷却を維持しながら、４７３ｇの液体臭素を加え、さらに４８％水酸化カリウム溶液２３０ｇを加え、組成物全体の量に対する重量比でスルファミン酸１０．７％、臭素１６．９％、臭素の当量に対するスルファミン酸の当量比が１．０４である、目的の安定化次亜臭素酸組成物を得た。生じた溶液のｐＨは、ガラス電極法にて測定したところ、１４であった。生じた溶液の臭素含有率は、臭素をヨウ化カリウムによりヨウ素に転換後、チオ硫酸ナトリウムを用いて酸化還元滴定する方法により測定したところ１６．９％であり、理論含有率（１６．９％）の１００．０％であった。また、臭素反応の際の反応容器内の酸素濃度は、株式会社ジコー製の「酸素モニタＪＫＯ－０２ ＬＪＤＩＩ」を用いて測定した。なお、臭素酸濃度は５ｍｇ／ｋｇ未満であった。 1436g of water and 361g of sodium hydroxide were added and mixed into a 2L four-necked flask sealed with continuous injection while controlling the flow rate of nitrogen gas with a mass flow controller so that the oxygen concentration in the reaction vessel was maintained at 1%, and then 300g of sulfamic acid was added and mixed. After that, 473g of liquid bromine was added while maintaining cooling so that the temperature of the reaction liquid was 0-15°C, and further 230g of 48% potassium hydroxide solution was added, and the target stabilized hypobromous acid composition was obtained, which has a weight ratio of 10.7% sulfamic acid, 16.9% bromine, and an equivalent ratio of sulfamic acid to bromine of 1.04 in terms of the weight ratio of the total amount of the composition. The pH of the resulting solution was 14 when measured by the glass electrode method. The bromine content of the resulting solution was 16.9% when measured by a method of converting bromine to iodine with potassium iodide and then performing oxidation-reduction titration with sodium thiosulfate, which was 100.0% of the theoretical content (16.9%). In addition, the oxygen concentration in the reaction vessel during the bromine reaction was measured using an oxygen monitor JKO-02 LJDII manufactured by JIKO Co., Ltd. The bromate concentration was less than 5 mg/kg.
なお、ｐＨの測定は、以下の条件で行った。
電極タイプ：ガラス電極式
ｐＨ測定計：東亜ディーケーケー社製、ＩＯＬ－３０型
電極の校正：関東化学社製中性リン酸塩ｐＨ（６．８６）標準液（第２種）、同社製ホウ酸塩ｐＨ（９．１８）標準液（第２種）の２点校正で行った
測定温度：２５℃
測定値：測定液に電極を浸漬し、安定後の値を測定値とし、３回測定の平均値
The pH measurement was carried out under the following conditions.
Electrode type: Glass electrode type pH meter: IOL-30 type, manufactured by DKK-TOA Electrode calibration: Two-point calibration was performed using neutral phosphate pH (6.86) standard solution (type 2) manufactured by Kanto Chemical Co., Ltd. and borate pH (9.18) standard solution (type 2) manufactured by the same company. Measurement temperature: 25°C
Measurement value: Immerse the electrode in the measurement solution, and the value after stabilization is the measurement value. The average value of three measurements is taken.
＜実施例１＞
図１に示す水回収装置を用い、被処理水として下水二次処理水（平均尿素濃度：６０μｇ／Ｌ、ＴＯＣ：７ｍｇ／Ｌ、アンモニア濃度：３５ｍｇ／Ｌ）を用いて水回収を行った。この被処理水に対し、除濁膜処理の前段である被処理水槽において殺菌剤として上記方法で調製した安定化次亜臭素酸組成物を１～８ｍｇ／Ｌ添加し、除濁膜処理水中の残留塩素濃度が０．０２～０．５０ｍｇ－Ｃｌ２／Ｌとなるようにしながら通水した。生物活性炭は、生物担体としての粒状活性炭「オルビーズＱＨＧ、オルガノ株式会社製」を５０Ｌボンベに充填したものを用いた。通水速度ＳＶは５とした。
Example 1
Water recovery was performed using the water recovery device shown in Figure 1 and secondary sewage treatment water (average urea concentration: 60 μg/L, TOC: 7 mg/L, ammonia concentration: 35 mg/L) as the water to be treated. 1 to 8 mg/L of the stabilized hypobromous acid composition prepared by the above method was added as a bactericide to the water to be treated in the water tank prior to the turbidity membrane treatment, and the water was passed through the tank while the residual chlorine concentration in the turbidity membrane treated water was 0.02 to 0.50 mg-Cl 2 /L. The biological activated carbon used was a granular activated carbon "Orbeez QHG, manufactured by Organo Corporation" filled in a 50 L cylinder as a biological carrier. The water passing speed SV was set to 5.
各条件で約２週間の通水後、逆浸透膜処理の透過水（ＲＯ透過水）中の尿素濃度を分析し、結果を図２に示した。 After passing water through each condition for about two weeks, the urea concentration in the permeate from the reverse osmosis membrane (RO permeate) was analyzed, and the results are shown in Figure 2.
なお、尿素濃度は、ＬＣ－ＭＳ（ＴｈｅｒｍｏＦｉｓｈｅｒＳｃｉｅｎｔｉｆｉｃ社製）を用いて測定した。ＴＯＣは、ＴＯＣ分析計（島津製作所製、燃焼式）を用いて測定した。アンモニア濃度は、イオンクロマトグラフ（ＴｈｅｒｍｏＦｉｓｈｅｒＳｃｉｅｎｔｉｆｉｃ社製）を用いて測定した。 The urea concentration was measured using an LC-MS (ThermoFisherScientific). The TOC was measured using a TOC analyzer (Shimadzu Corporation, combustion type). The ammonia concentration was measured using an ion chromatograph (ThermoFisherScientific).
いずれの添加量においても、尿素濃度を十分低減することができていた。また、除濁膜の通水差圧の推移を図３に示す。安定化次亜臭素酸組成物を除濁膜処理水中の残留塩素濃度が０．０５ｍｇ－Ｃｌ２／Ｌ以上となるように添加した場合は、通水差圧がほとんど上昇しなかった。安定化次亜臭素酸組成物を除濁膜処理水中の残留塩素濃度が０．０２ｍｇ－Ｃｌ２／Ｌとなるように添加した場合は、４５日目までは通水差圧がほとんど上昇せず、生物等による閉塞を抑制することができていたが、４６日目以降は、通水差圧が上昇した。 In any of the amounts added, the urea concentration could be sufficiently reduced. The transition of the water passing differential pressure of the turbidity removal membrane is shown in FIG. 3. When the stabilized hypobromous acid composition was added so that the residual chlorine concentration in the turbidity removal membrane treated water was 0.05 mg-Cl 2 /L or more, the water passing differential pressure hardly increased. When the stabilized hypobromous acid composition was added so that the residual chlorine concentration in the turbidity removal membrane treated water was 0.02 mg-Cl 2 /L, the water passing differential pressure hardly increased until the 45th day, and clogging by organisms and the like could be suppressed, but from the 46th day onwards, the water passing differential pressure increased.
＜参考例２＞
殺菌剤として次亜塩素酸を添加し、実施例１と同様にして通水を行った。逆浸透膜処理の透過水中の尿素濃度の測定結果を図２に示す。
< Reference Example 2>
Hypochlorous acid was added as a disinfectant, and water was passed through in the same manner as in Example 1. The measurement results of the urea concentration in the permeate after the reverse osmosis membrane treatment are shown in FIG.
除濁膜処理水中の残留塩素濃度が高くなると、生物活性炭における生物の繁殖が阻害されるため、実施例１に比べると尿素濃度が高くなっているが、残留塩素濃度０．０５ｍｇ／Ｌ以下のときは尿素濃度を低減できていた。また、残留塩素濃度を０．０２ｍｇ／Ｌとすると、除濁膜での通水差圧が上昇する傾向は実施例１と同様であった。 When the residual chlorine concentration in the turbidity removal membrane treated water becomes high, the reproduction of organisms in the biological activated carbon is inhibited, and so the urea concentration is higher than in Example 1. However, when the residual chlorine concentration was 0.05 mg/L or less, the urea concentration was reduced. In addition, when the residual chlorine concentration was set to 0.02 mg/L, the tendency for the water flow differential pressure through the turbidity removal membrane to increase was the same as in Example 1.
上記の通り、実施例の水回収方法によれば、尿素を効率的に分解しつつ、除濁膜での差圧上昇を抑制して運転することが可能であることが確認された。 As described above, it was confirmed that the water recovery method of the embodiment can efficiently decompose urea while suppressing the increase in differential pressure at the turbidity removal membrane.
このように、実施例の水回収方法によれば、尿素を含む被処理水からの水回収において、除濁膜での生物等による閉塞を抑制することができ、かつ生物活性炭における閉塞を抑制し、尿素分解菌の生成を大きく抑制することなく、尿素の除去が可能であった。これにより、逆浸透膜処理の透過水を純水の原水として再利用することも可能である。 In this way, according to the water recovery method of the embodiment, in recovering water from treated water containing urea, it was possible to suppress clogging of the turbidity membrane by organisms, and also to suppress clogging of the biological activated carbon, making it possible to remove urea without significantly suppressing the production of urea-decomposing bacteria. This makes it possible to reuse the permeate from the reverse osmosis membrane treatment as raw water for pure water.
１ 水回収装置、１０ 被処理水槽、１２ 除濁膜処理装置、１４ 除濁膜処理水槽、１６ 生物活性炭処理装置、１８ 活性炭処理水槽、２０ 逆浸透膜処理装置、２２，２４，２６，２８ ポンプ、３０，３２ 被処理水配管、３４，３６ 除濁膜処理水配管、３８，４０ 活性炭処理水配管、４２ 透過水配管、４４ 濃縮水配管、４６ 逆洗水配管、４８ 逆洗排水配管、５０ 殺菌剤添加配管。 1 Water recovery device, 10 Water tank to be treated, 12 Turbidity removal membrane treatment device, 14 Turbidity removal membrane treatment tank, 16 Biological activated carbon treatment device, 18 Activated carbon treatment tank, 20 Reverse osmosis membrane treatment device, 22, 24, 26, 28 Pump, 30, 32 Water to be treated piping, 34, 36 Turbidity removal membrane treated water piping, 38, 40 Activated carbon treated water piping, 42 Permeate water piping, 44 Concentrated water piping, 46 Backwash water piping, 48 Backwash drainage piping, 50 Disinfectant addition piping.
Claims (8)
前記逆浸透膜処理の前処理として除濁膜処理、および担体である活性炭上に尿素分解菌を担持させた生物活性炭処理を順に行い、前記除濁膜処理の前段において殺菌剤を添加し、
前記殺菌剤が、臭素系酸化剤とスルファミン酸化合物とを含む安定化次亜臭素酸組成物であることを特徴とする水回収方法。 A water recovery method for recovering water by performing reverse osmosis membrane treatment on water to be treated that contains urea, comprising the steps of:
As a pretreatment for the reverse osmosis membrane treatment , a turbidity removal membrane treatment and a biological activated carbon treatment in which urea decomposition bacteria are supported on activated carbon as a carrier are performed in this order, and a bactericide is added in the stage before the turbidity removal membrane treatment ,
2. A method for recovering water, comprising the step of: providing a disinfectant comprising a stabilized hypobromous acid composition comprising a bromine-based oxidizing agent and a sulfamic acid compound .
前記除濁膜処理で得られる除濁膜処理水中の残留塩素濃度が０．０２～０．５ｍｇ－Ｃｌ２／Ｌの範囲となるように前記安定化次亜臭素酸組成物を添加することを特徴とする水回収方法。 2. The water recovery method according to claim 1 ,
The water recovery method comprises adding the stabilized hypobromous acid composition so that the residual chlorine concentration in the turbidity membrane treated water obtained by the turbidity membrane treatment is in the range of 0.02 to 0.5 mg-Cl 2 /L.
前記被処理水が下水処理水であり、前記逆浸透膜処理の透過水を半導体工場の純水製造の原水として回収することを特徴とする水回収方法。 The water recovery method according to claim 1 or 2 ,
The water recovery method is characterized in that the water to be treated is sewage treatment water, and the permeate of the reverse osmosis membrane treatment is recovered as raw water for producing pure water in a semiconductor factory.
前記逆浸透膜処理の後段において、第２の逆浸透膜処理、ＵＶ処理、または、イオン交換処理のうちの少なくとも１つを行うことを特徴とする水回収方法。 The water recovery method according to any one of claims 1 to 3 ,
A water recovery method, comprising the steps of: performing at least one of a second reverse osmosis membrane treatment, a UV treatment, or an ion exchange treatment in a stage subsequent to the reverse osmosis membrane treatment.
前記逆浸透膜処理の前処理として除濁膜処理、および担体である活性炭上に尿素分解菌を担持させた生物活性炭処理を順に行う除濁膜処理手段および生物活性炭処理手段と、
前記除濁膜処理の前段において殺菌剤を添加する殺菌剤添加手段と、
を備え、
前記殺菌剤が、臭素系酸化剤とスルファミン酸化合物とを含む安定化次亜臭素酸組成物であることを特徴とする水回収装置。 A water recovery apparatus including a reverse osmosis membrane treatment means for performing reverse osmosis membrane treatment on urea-containing water to be treated and recovering the water,
a turbidity removing membrane treatment means and a biological activated carbon treatment means, which sequentially perform a turbidity removing membrane treatment as a pretreatment for the reverse osmosis membrane treatment and a biological activated carbon treatment in which urea decomposition bacteria are supported on activated carbon as a carrier ;
A bactericide adding means for adding a bactericide in a stage preceding the turbidity removing membrane treatment;
Equipped with
1. A water recovery apparatus, wherein the bactericide is a stabilized hypobromous acid composition containing a bromine-based oxidizing agent and a sulfamic acid compound .
前記殺菌剤添加手段は、前記除濁膜処理で得られる除濁膜処理水中の残留塩素濃度が０．０２～０．５ｍｇ－Ｃｌ２／Ｌの範囲となるように前記安定化次亜臭素酸組成物を添加することを特徴とする水回収装置。 6. The water recovery device according to claim 5 ,
The water recovery apparatus is characterized in that the bactericide adding means adds the stabilized hypobromous acid composition so that the residual chlorine concentration in the turbidity membrane treated water obtained by the turbidity membrane treatment is in the range of 0.02 to 0.5 mg-Cl 2 /L.
前記被処理水が下水処理水であり、前記逆浸透膜処理の透過水を半導体工場の純水製造の原水として回収することを特徴とする水回収装置。 7. The water recovery device according to claim 5 or 6 ,
The water recovery apparatus is characterized in that the water to be treated is sewage treatment water, and the permeate of the reverse osmosis membrane treatment is recovered as raw water for producing pure water in a semiconductor factory.
前記逆浸透膜処理手段の後段に、第２の逆浸透膜処理手段、ＵＶ処理手段、または、イオン交換処理手段のうちの少なくとも１つを備えることを特徴とする水回収装置。 The water recovery device according to any one of claims 5 to 7 ,
A water recovery apparatus comprising at least one of a second reverse osmosis membrane treatment means, a UV treatment means, and an ion exchange treatment means, downstream of the reverse osmosis membrane treatment means.
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