JP2018035024A - Method for producing sodium hypochlorite, and sodium hypochlorite production device - Google Patents
Method for producing sodium hypochlorite, and sodium hypochlorite production device Download PDFInfo
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- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 title claims abstract description 65
- 239000005708 Sodium hypochlorite Substances 0.000 title claims abstract description 63
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 39
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 215
- 238000011282 treatment Methods 0.000 claims abstract description 131
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 98
- 238000000034 method Methods 0.000 claims abstract description 87
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 66
- 150000003839 salts Chemical class 0.000 claims abstract description 58
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 56
- 239000011575 calcium Substances 0.000 claims abstract description 55
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 55
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 39
- 239000002351 wastewater Substances 0.000 claims abstract description 29
- 239000003014 ion exchange membrane Substances 0.000 claims abstract description 25
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 claims abstract description 23
- 235000011121 sodium hydroxide Nutrition 0.000 claims abstract description 22
- 238000001179 sorption measurement Methods 0.000 claims abstract description 20
- 239000013522 chelant Substances 0.000 claims abstract description 17
- 238000001556 precipitation Methods 0.000 claims abstract description 11
- 230000002194 synthesizing effect Effects 0.000 claims abstract description 7
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 33
- 238000011033 desalting Methods 0.000 claims description 25
- 238000000909 electrodialysis Methods 0.000 claims description 17
- 239000012528 membrane Substances 0.000 claims description 16
- 239000002994 raw material Substances 0.000 claims description 14
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- 238000010612 desalination reaction Methods 0.000 claims description 10
- 238000003786 synthesis reaction Methods 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- 239000000126 substance Substances 0.000 abstract description 11
- 229920006395 saturated elastomer Polymers 0.000 description 22
- 239000000460 chlorine Substances 0.000 description 19
- 229910052801 chlorine Inorganic materials 0.000 description 18
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 15
- 238000001223 reverse osmosis Methods 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 239000002699 waste material Substances 0.000 description 6
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 239000011777 magnesium Substances 0.000 description 5
- 229910052749 magnesium Inorganic materials 0.000 description 5
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000012141 concentrate Substances 0.000 description 4
- 239000011259 mixed solution Substances 0.000 description 4
- 238000004065 wastewater treatment Methods 0.000 description 4
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 3
- -1 Chlorine ions Chemical class 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 3
- 235000011941 Tilia x europaea Nutrition 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000004571 lime Substances 0.000 description 3
- 239000003206 sterilizing agent Substances 0.000 description 3
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 229910001424 calcium ion Inorganic materials 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 239000008151 electrolyte solution Substances 0.000 description 2
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000012465 retentate Substances 0.000 description 2
- 238000009287 sand filtration Methods 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000008399 tap water Substances 0.000 description 2
- 235000020679 tap water Nutrition 0.000 description 2
- 239000002912 waste gas Substances 0.000 description 2
- BZSXEZOLBIJVQK-UHFFFAOYSA-N 2-methylsulfonylbenzoic acid Chemical compound CS(=O)(=O)C1=CC=CC=C1C(O)=O BZSXEZOLBIJVQK-UHFFFAOYSA-N 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 229920001429 chelating resin Polymers 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000006103 coloring component Substances 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 238000001471 micro-filtration Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- SATVIFGJTRRDQU-UHFFFAOYSA-N potassium hypochlorite Chemical compound [K+].Cl[O-] SATVIFGJTRRDQU-UHFFFAOYSA-N 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
Images
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
Abstract
Description
本発明は、高塩類含有廃水由来の脱塩濃縮水のリサイクルのための次亜塩素酸ソーダの製造方法及び次亜塩素酸ソーダの製造装置に関する。 The present invention relates to a method for producing sodium hypochlorite and a sodium hypochlorite production apparatus for recycling desalted concentrated water derived from wastewater containing high salt.
近年、焼却残渣を埋め立てた最終処分場では、浸出水の高塩類化が進んでいる。浸出水を脱塩処理している施設ではその処理プロセスから排出される脱塩処理時の濃縮水および乾燥塩の処理が問題になっている。このような濃縮水および乾燥塩をリサイクルするために滅菌剤の生成処理が実用化されつつある。 In recent years, high salinity of leachate has been progressing at final disposal sites where incineration residues have been landfilled. In the facility that desalinates leachate, the treatment of concentrated water and dry salt discharged during the desalting process is a problem. In order to recycle such concentrated water and dried salt, a sterilizing agent generation process is being put into practical use.
最終処分場の浸出水を脱塩処理する際に発生する脱塩濃縮水以外に、都市ごみ焼却炉や溶融炉に備えた湿式排ガス処理装置で生じる洗煙排水や、乾式二段バグフィルタの後段側のナトリウム系脱塩剤噴霧残渣等の高塩類含有廃水由来の脱塩濃縮水も同様に滅菌剤としてリサイクルすることができる。 In addition to desalted and concentrated water generated when desalting the leachate at the final disposal site, smoke sewage generated in wet waste gas treatment equipment in municipal waste incinerators and melting furnaces, and the latter stage of the dry two-stage bag filter Similarly, desalted concentrated water derived from high salt-containing wastewater such as sodium-based desalting agent spray residue on the side can be recycled as a sterilant.
特許文献１には、脱塩濃縮処理水を電解処理して次亜塩素酸溶液を生成する際に、カルシウム及びマグネシウム由来のスケールの析出を抑制して安定した電解処理を行うことができる有機性廃水の処理方法が提案されている。
In
当該有機性廃水の処理方法は、塩類及び有機物を含有する有機性廃水に対して、軟化処理を行ってカルシウム濃度を低減させる第１軟化処理工程と、生物処理、凝集沈殿処理、活性炭吸着処理、砂ろ過処理、精密ろ過膜処理からなる群から選ばれる１以上の処理または２以上の組み合わせからなるＳＳ除去処理工程とを備えると共に、前記第１軟化処理工程及びＳＳ除去処理工程を実施した後に、電気透析処理により電気透析濃縮水と電気透析処理水とに分離する電気透析処理工程と、逆浸透膜処理により逆浸透濃縮水と逆浸透膜処理水とに分離する逆浸透膜処理工程と、ＮＦ膜処理によりＮＦ膜濃縮水とＮＦ膜処理水とに分離するＮＦ膜処理工程のうちの何れかの工程或いは２種類以上の工程を含む塩類除去処理工程を備え、前記塩類除去工程で得られた塩類濃縮水、すなわち電気透析濃縮水、逆浸透濃縮水又はＮＦ膜濃縮水に対して、軟化処理を行ってカルシウム濃度を低減させる第２軟化処理工程を実施し、次いで、第２軟化処理工程で得られた第２軟化処理水を電気分解して次亜塩素酸ナトリウム溶液を生成する電解処理工程を実施するように構成されている。 The organic wastewater treatment method includes a first softening treatment step in which organic wastewater containing salts and organic matter is softened to reduce calcium concentration, biological treatment, coagulation sedimentation treatment, activated carbon adsorption treatment, After carrying out the first softening treatment step and the SS removal treatment step, including sand filtration treatment, SS removal treatment step consisting of one or more treatments selected from the group consisting of microfiltration membrane treatment or a combination of two or more, An electrodialysis treatment step for separating electrodialyzed concentrated water and electrodialyzed water by electrodialysis treatment, a reverse osmosis membrane treatment step for separating reverse osmosis concentrated water and reverse osmosis membrane treated water by reverse osmosis membrane treatment, and NF A salt removal treatment step including any step or two or more types of NF membrane treatment steps for separating NF membrane concentrated water and NF membrane treated water by membrane treatment; The salt concentration water obtained in the above step, that is, electrodialysis concentration water, reverse osmosis concentration water or NF membrane concentration water, is subjected to a second softening treatment step for reducing the calcium concentration by performing a softening treatment, The electrolysis process which produces | generates a sodium hypochlorite solution by electrolyzing the 2nd softening process water obtained at the 2 softening process process is implemented.
上述の有機性廃水の処理方法によれば、電解処理工程で被処理水のｐＨを１０以上に調整して電気分解することにより、有効塩素濃度を２５００ｍｇ／Ｌと安定させることができるようになる。 According to the organic wastewater treatment method described above, the effective chlorine concentration can be stabilized at 2500 mg / L by electrolysis by adjusting the pH of the water to be treated to 10 or more in the electrolytic treatment step. .
しかし、特許文献１に開示された有機性廃水の処理方法によれば、電解処理工程で用いられる電解処理装置が、軟化処理工程で得られた軟化処理水を電気分解して次亜塩素酸ナトリウム溶液を生成する電解処理装置、つまり電解槽で電解により生成された塩素ガス及び苛性ソーダを槽内で反応させて次亜塩素酸ソーダを生成する無隔膜法を採用した電解処理装置を用いるため、生成される次亜塩素酸ソーダの濃度が０．５％以下に制限されるという問題があった。
However, according to the organic wastewater treatment method disclosed in
無隔膜法を採用する場合には電解水を精製するための前処理の精度がそれほど要求されない。しかし、電解効率もそれほど高くないため高濃度の次亜塩素酸ソーダを製造することができないのであった。 When the non-diaphragm method is adopted, the accuracy of pretreatment for purifying the electrolyzed water is not so required. However, since electrolysis efficiency is not so high, high concentration sodium hypochlorite cannot be produced.
脱塩濃縮水からイオン交換膜法を用いて苛性ソーダと塩素ガスを生成する電解法を採用すると、電解効率及び純度が高く数％以上の高濃度の次亜塩素酸ソーダを製造することが期待できるのであるが、電解水を精製するための高い精度の前処理、例えばカルシウム濃度やマグネシウム濃度をμｇ／Ｌオーダーに調整する必要があった。 Adopting an electrolytic method that produces caustic soda and chlorine gas from desalted concentrated water using an ion exchange membrane method, it is expected to produce high-concentration sodium hypochlorite with high electrolytic efficiency and purity of several percent or more. However, it has been necessary to adjust the pretreatment with high accuracy for purifying the electrolyzed water, for example, the calcium concentration and the magnesium concentration to the order of μg / L.
カルシウム濃度やマグネシウム濃度が高いと電解槽に配置されたイオン交換膜にそれらに起因するスケールが付着し、電流を確保するために必要な電解電圧が上昇して数十時間で電解槽の運転を停止せざるを得ない状況になっていたためである。 If the calcium or magnesium concentration is high, the scale caused by them adheres to the ion exchange membrane placed in the electrolytic cell, and the electrolytic voltage necessary to secure the current rises, so that the electrolytic cell can be operated in several tens of hours. This is because the situation had to be stopped.
そこで、本願発明者らは、高塩類含有廃水由来の脱塩濃縮水からカルシウムやマグネシウム等のスケール原因物質を効果的に除去して、長時間連続して電解処理を可能にすることで、高濃度の次亜塩素酸ソーダを得ることができる次亜塩素酸ソーダの製造方法及び次亜塩素酸ソーダの製造装置を提案している（特願２０１５−２４９４９５号）。 Therefore, the inventors of the present application effectively remove scale-causing substances such as calcium and magnesium from desalted and concentrated water derived from high-salt-containing wastewater, and enable electrolytic treatment continuously for a long time. A sodium hypochlorite manufacturing method and a sodium hypochlorite manufacturing apparatus capable of obtaining sodium hypochlorite having a high concentration are proposed (Japanese Patent Application No. 2015-249495).
ところで、先の特許出願（特願２０１５−２４９４９５号）では、脱塩濃縮水に乾燥塩を添加して最も電解条件の良い飽和塩水とした後に電解処理するように構成されていたため、乾燥塩添加機構及び撹拌機構を備えた原料塩溶解槽を設置して、十分な量の乾燥塩を準備する必要があり、設備コストやランニングコストの上昇を抑制するという観点でさらなる改良の余地があった。 By the way, in the previous patent application (Japanese Patent Application No. 2015-249495), the dry salt was added to the desalted concentrated water to obtain the saturated salt water having the best electrolysis conditions, and then subjected to electrolytic treatment. It is necessary to prepare a raw material salt dissolution tank equipped with a mechanism and a stirring mechanism to prepare a sufficient amount of dry salt, and there is room for further improvement from the viewpoint of suppressing an increase in equipment cost and running cost.
本発明の目的は、上述した問題点に鑑み、製造コストを抑制しつつ、高塩類含有廃水由来の脱塩濃縮水からスケール原因物質を効果的に除去して、効率的に高濃度の次亜塩素酸ソーダを得ることができる次亜塩素酸ソーダの製造方法及び次亜塩素酸ソーダの製造装置を提供する点にある。 In view of the above-mentioned problems, the object of the present invention is to effectively remove scale-causing substances from desalted and concentrated water derived from high-salt-containing wastewater while suppressing production costs, and to efficiently remove high-concentration hypochlorous acid. The object is to provide a method for producing sodium hypochlorite and an apparatus for producing sodium hypochlorite from which sodium chlorate can be obtained.
上述の目的を達成するため、本発明による次亜塩素酸ソーダの製造方法の第一の特徴構成は、特許請求の範囲の請求項１に記載した通り、高塩類含有廃水由来の脱塩濃縮水を所定の塩素イオン濃度を示す不飽和状態で軟化処理してカルシウム濃度を低下させる軟化処理工程と、前記軟化処理工程で軟化処理された脱塩濃縮水から、イオン交換膜法を用いて苛性ソーダと塩素ガスを生成する電解工程と、前記電解工程で生成された苛性ソーダと塩素ガスとから次亜塩素酸ソーダを合成する次亜塩素酸ソーダ合成工程とを備え、前記軟化処理工程は、脱塩濃縮水に対して沈殿法でカルシウム濃度を低下させる第１軟化処理工程と、前記第１軟化処理工程の後にキレート吸着法でカルシウム濃度をさらに低下させる第２軟化処理工程を含む点にある。
In order to achieve the above-mentioned object, the first characteristic configuration of the method for producing sodium hypochlorite according to the present invention is the desalted concentrated water derived from high salt-containing wastewater as described in
所定の塩素イオン濃度を示す不飽和状態の高塩類含有廃水由来の脱塩濃縮水に対して、先ず沈殿法でカルシウム濃度を低下させた後に、キレート吸着法でさらにカルシウム濃度を低下させることにより、高価なキレートを長期に渡り機能させることが可能になり、その結果イオン交換膜へのスケールの付着が効果的に抑制され、長時間にわたって電解工程を継続させることができ、高濃度の次亜塩素酸ソーダを得ることができる。しかも、所定の塩素イオン濃度を示す不飽和状態の脱塩濃縮水を用いることにより、飽和濃縮水を得るための乾燥塩の添加工程が不要になり、そのための設備コストや薬剤コストを低減できるようになった。 For desalted concentrated water derived from unsaturated high salt-containing wastewater showing a predetermined chloride ion concentration, first by reducing the calcium concentration by precipitation method, then by further reducing the calcium concentration by chelate adsorption method, Expensive chelates can function over a long period of time. As a result, scale adhesion to the ion exchange membrane is effectively suppressed, and the electrolysis process can be continued for a long time. Acid soda can be obtained. Moreover, the use of desalted concentrated water in an unsaturated state exhibiting a predetermined chloride ion concentration eliminates the need for a dry salt addition step for obtaining saturated concentrated water, thereby reducing equipment costs and chemical costs for that purpose. Became.
同第二の特徴構成は、同請求項２に記載した通り、上述の第一の特徴構成に加えて、前記脱塩濃縮水を塩素イオン濃度が前記所定の塩素イオン濃度未満のときに、原料塩を添加して塩素イオン濃度を前記所定の塩素イオン濃度以上に調整する塩素イオン濃度調整工程を備えている点にある。 As described in the second aspect, the second characteristic configuration is the raw material when, in addition to the first characteristic configuration, the desalted concentrated water has a chlorine ion concentration less than the predetermined chlorine ion concentration. A point is that it includes a chlorine ion concentration adjusting step of adjusting the chlorine ion concentration to be equal to or higher than the predetermined chlorine ion concentration by adding salt.
塩素イオン濃度が所定の塩素イオン濃度未満の脱塩濃縮水であれば、イオン交換膜法を用いた電解工程の実行中に、脱塩濃縮水中の塩素イオンのほとんどが塩素ガスとなって電気伝導度が低下し、イオン交換膜の損傷を来す虞がある。そこで、脱塩濃縮水の塩素イオン濃度が所定の塩素イオン濃度に満たない場合にのみ原料塩を添加すれば、また乾燥塩の必要量も大きく低減でき、製造コストを効果的に低減できるようになった。 If the desalted and concentrated water has a chloride ion concentration less than the specified chloride ion concentration, most of the chloride ions in the desalted and concentrated water are converted into chlorine gas during the electrolysis process using the ion-exchange membrane method. There is a risk that the ion exchange membrane will be damaged. Therefore, if the raw material salt is added only when the chlorine ion concentration of the desalted concentrated water is less than the predetermined chlorine ion concentration, the necessary amount of dry salt can be greatly reduced, and the production cost can be effectively reduced. became.
同第三の特徴構成は、同請求項３に記載した通り、上述の第一の特徴構成に加えて、高塩類含有廃水から前記所定の塩素イオン濃度の脱塩濃縮水にまで濃縮処理する脱塩濃縮処理工程をさらに備えている点にある。 In addition to the first feature configuration described above, the third feature configuration is a desalination process that concentrates from high-salt-containing wastewater to desalted concentrated water having a predetermined chloride ion concentration. A salt concentration treatment step is further provided.
高塩類含有廃水を脱塩処理して排水する際に塩素イオンの濃縮処理が行なわれる。その際に所定の塩素イオン濃度の脱塩濃縮水に濃縮処理すれば、別途の原料塩を添加するような追加処理が不要になる。 When waste water containing high salt is desalted and drained, concentration treatment of chloride ions is performed. At this time, if the concentration treatment is performed on desalted and concentrated water having a predetermined chloride ion concentration, an additional treatment such as adding a separate raw material salt becomes unnecessary.
同第四の特徴構成は、同請求項４に記載した通り、上述の第一から第三の何れかの特徴構成に加えて、前記脱塩濃縮水が最終処分場の浸出水を脱塩処理して得られる脱塩濃縮水であり、前記所定の塩素イオン濃度が８００００ｍｇ／Ｌ以上の脱塩濃縮水である点にある。 In the fourth feature configuration, as described in claim 4, in addition to any of the first to third feature configurations described above, the desalted concentrated water desalinates leachate from the final disposal site. Desalted and concentrated water obtained by the above-described process, wherein the predetermined chlorine ion concentration is 80000 mg / L or higher.
塩素イオン濃度が８００００ｍｇ／Ｌ以上の脱塩濃縮水であれば、イオン交換膜法を用いた電解工程を安定的に継続して実行できるようになり、好ましい。塩素イオン濃度が８００００ｍｇ／Ｌ未満の脱塩濃縮水であれば、上述したようにイオン交換膜法を用いた電解工程の実行中に、脱塩濃縮水中の塩素イオンのほとんどが塩素ガスとなって電気伝導度が低下し、イオン交換膜の損傷を来す虞がある。尚、このようなイオン交換膜の損傷を回避するために、脱塩濃縮水の流量を増加させると塩素ガスの生成効率が低下することになる。 A desalted concentrated water having a chloride ion concentration of 80000 mg / L or more is preferable because the electrolytic process using the ion exchange membrane method can be carried out stably and continuously. If the desalted concentrated water has a chloride ion concentration of less than 80000 mg / L, most of the chloride ions in the desalted concentrated water become chlorine gas during the electrolysis process using the ion exchange membrane method as described above. There is a possibility that the electric conductivity is lowered and the ion exchange membrane is damaged. In addition, in order to avoid such damage of the ion exchange membrane, if the flow rate of the desalted concentrated water is increased, the generation efficiency of chlorine gas is lowered.
同第五の特徴構成は、同請求項５に記載した通り、上述の第四の特徴構成に加えて、前記脱塩濃縮水は塩素イオン濃度が５０００ｍｇ／Ｌ以上の最終処分場の浸出水を脱塩処理して得られる脱塩濃縮水である点にある。 In the fifth feature configuration, as described in claim 5, in addition to the fourth feature configuration described above, the desalted and concentrated water contains leachate from a final disposal site having a chloride ion concentration of 5000 mg / L or more. This is a desalted concentrated water obtained by desalting.
最終処分場の浸出水の塩素イオン濃度が５０００ｍｇ／Ｌ以上であれば、適切に脱塩しながら、塩素イオン濃度が８００００ｍｇ／Ｌ以上の脱塩濃縮水に濃縮処理できるようになる。 If the chlorine ion concentration of the leachate in the final disposal site is 5000 mg / L or more, it can be concentrated to desalted concentrated water having a chlorine ion concentration of 80000 mg / L or more while appropriately desalting.
同第六の特徴構成は、同請求項６に記載した通り、上述の第一から第五の何れかの特徴構成に加えて、前記脱塩濃縮水は塩素イオン濃度が５０００〜１５０００ｍｇ／Ｌの最終処分場の浸出水を電気透析法で脱塩処理して得られる脱塩濃縮水であり、前記所定の塩素イオン濃度が８００００〜１０００００ｍｇ／Ｌの脱塩濃縮水である点にある。 In addition to any one of the first to fifth feature configurations described above, the sixth feature configuration has a chloride ion concentration of 5000 to 15000 mg / L in addition to any of the first to fifth feature configurations described above. This is desalted concentrated water obtained by desalting the leachate from the final disposal site by electrodialysis, and is the desalted concentrated water having a predetermined chloride ion concentration of 80000 to 100,000 mg / L.
電気透析法で脱塩処理する場合、最終処分場の浸出水の塩素イオン濃度が５０００〜１５０００ｍｇ／Ｌの範囲であれば、効率的に塩素イオン濃度が８００００〜１０００００ｍｇ／Ｌの脱塩濃縮水を得ることができる。 In the case of desalting by electrodialysis, if the chlorine ion concentration of the leachate in the final disposal site is in the range of 5000 to 15000 mg / L, the desalted concentrated water having a chlorine ion concentration of 80000 to 100,000 mg / L is efficiently obtained. Can be obtained.
同第七の特徴構成は、同請求項７に記載した通り、上述の第一から第六の何れかの特徴構成に加えて、前記第１軟化処理工程は、脱塩濃縮水をｐＨ１０以上に調整して、脱塩濃縮水に含有するカルシウム濃度に対して理論値より多い２〜１０モルの炭酸ソーダを注入する工程を含む点にある。 In addition to any one of the first to sixth characteristic configurations described above, the seventh characteristic configuration includes the first softening treatment step, wherein the desalted concentrated water is adjusted to a pH of 10 or more. It is the point which includes the process which inject | pours 2-10 mol sodium carbonate more than a theoretical value with respect to the calcium concentration which adjusts and contains in desalted concentrated water.
本願発明者らは、鋭意研究を重ねた結果、脱塩濃縮水のｐＨを高アルカリ状態に調整して炭酸ソーダを過剰気味に注入することによって、効果的に脱塩濃縮水中のカルシウム濃度を低下させることができるという新知見を得た。ｐＨ１０以上に調整し、炭酸ソーダを脱塩濃縮水のカルシウム濃度に対して２〜１０モル、理論値（１モル）より過剰気味に注入することにより、脱塩濃縮水にイオンとして含有されるカルシウムと炭酸ソーダとの反応を促進させることができるようになるのである。 As a result of extensive research, the inventors of the present application have effectively reduced the calcium concentration in the desalted concentrated water by adjusting the pH of the desalted concentrated water to a high alkaline state and injecting sodium carbonate excessively. New knowledge that can be made. Calcium contained as ions in the desalted concentrated water by adjusting the pH to 10 or more and injecting sodium carbonate in excess of 2 to 10 mol, theoretical value (1 mol) with respect to the calcium concentration of the desalted concentrated water. It becomes possible to promote the reaction between sodium carbonate and sodium carbonate.
同第八の特徴構成は、同請求項８に記載した通り、上述の第一から第五の何れかの特徴構成に加えて、第２軟化処理工程は、キレート吸着法でカルシウム濃度を１ｍｇ／Ｌ以下に低下させる工程である点にある。
In the eighth feature configuration, as described in
第２軟化処理工程でカルシウム濃度を１ｍｇ／Ｌ以下に低下させると、イオン交換膜へのスケールの付着がより効果的に抑制され、より一層長時間にわたって電解工程を継続させることができる。 When the calcium concentration is reduced to 1 mg / L or less in the second softening treatment step, scale adhesion to the ion exchange membrane is more effectively suppressed, and the electrolysis step can be continued for a longer time.
同第九の特徴構成は、同請求項９に記載した通り、上述の第一から第八の何れかの特徴構成に加えて、前記軟化処理工程の前に高塩類含有廃水由来の脱塩濃縮水のカルシウム濃度を１００ｍｇ／Ｌ以下に低下させる前置軟化処理工程と脱塩処理工程をさらに備えている点にある。 In addition to any one of the first to eighth feature configurations described above, the ninth feature configuration is desalted and concentrated from high salt-containing wastewater before the softening treatment step. It is in the point further equipped with the pre-softening process and the desalination process which reduce the calcium concentration of water to 100 mg / L or less.
前置軟化処理工程と脱塩処理工程で脱塩濃縮水のカルシウム濃度を１００ｍｇ／Ｌ以下に低下させておけば、第１軟化処理工程および第２軟化処理工程で効果的にカルシウム濃度を低下させることができ、イオン交換膜へのスケールの付着を効果的に抑制することができるようになる。 If the calcium concentration of desalted concentrated water is reduced to 100 mg / L or less in the pre-softening treatment step and the desalting treatment step, the calcium concentration is effectively reduced in the first softening treatment step and the second softening treatment step. It is possible to effectively suppress adhesion of scale to the ion exchange membrane.
同第十の特徴構成は、同請求項１０に記載した通り、上述の第一から第九の何れかの特徴構成に加えて、前記軟化処理工程の前に、高塩類含有廃水由来の脱塩濃縮水のカルシウム濃度を低下させる前置軟化処理工程と、生物処理工程と、凝集膜分離工程と、活性炭吸着処理工程と、キレート吸着処理工程とからなる群から選ばれる１以上の処理工程または２以上の処理工程の組合せからなる前処理工程を備えている点にある。
In the tenth feature, as described in
本発明による次亜塩素酸ソーダの製造装置の第一の特徴構成は、同請求項１１に記載した通り、高塩類含有廃水由来の脱塩濃縮水を所定の塩素イオン濃度を示す不飽和状態で軟化処理してカルシウム濃度を低下させる軟化処理装置と、前記軟化処理装置で軟化処理された脱塩濃縮水から、イオン交換膜法を用いて苛性ソーダと塩素ガスを生成する電解装置と、前記電解装置で生成された苛性ソーダと塩素ガスとから次亜塩素酸ソーダを合成する次亜塩素酸ソーダ合成装置とを備え、前記軟化処理装置は、脱塩濃縮水に対して沈殿法でカルシウム濃度を低下させる第１軟化処理装置と、前記第１軟化処理装置の後にキレート吸着法でカルシウム濃度を低下させる第２軟化処理装置を含む点にある。
The first feature of the apparatus for producing sodium hypochlorite according to the present invention is the desalted and concentrated water derived from high salt-containing wastewater in an unsaturated state having a predetermined chlorine ion concentration as described in
同第二の特徴構成は、同請求項１２に記載した通り、上述の第一の特徴構成に加えて、脱塩濃縮水の塩素イオン濃度が前記所定の塩素イオン濃度未満のときに、前記軟化処理装置に供給する脱塩濃縮水に原料塩を添加して塩素イオン濃度を前記所定の塩素イオン濃度以上に調整して塩素イオン濃度調整装置を備えている点にある。 In the second feature configuration, in addition to the first feature configuration described above, when the chloride ion concentration of the desalted concentrated water is less than the predetermined chloride ion concentration, the softening is performed. The raw material salt is added to the desalted concentrated water supplied to the treatment apparatus, and the chlorine ion concentration is adjusted to be equal to or higher than the predetermined chlorine ion concentration, thereby providing a chlorine ion concentration adjusting device.
同第三の特徴構成は、同請求項１３に記載した通り、上述の第一または第二の特徴構成に加えて、脱塩濃縮水の塩素イオン濃度が前記所定の塩素イオン濃度未満のときに、脱塩濃縮水の塩素イオン濃度が前記所定の塩素イオン濃度以上になるまで脱塩濃縮水の前記軟化処理装置への供給を停止する供給停止機構を備えている点にある。 In addition to the first or second characteristic configuration described above, when the chlorine ion concentration of the desalted concentrated water is less than the predetermined chlorine ion concentration, the third characteristic configuration is In addition, there is a supply stop mechanism for stopping the supply of the desalted concentrated water to the softening device until the chlorine ion concentration of the desalted concentrated water becomes equal to or higher than the predetermined chlorine ion concentration.
以上説明した通り、本発明によれば、製造コストを抑制しつつ、高塩類含有廃水由来の脱塩濃縮水からスケール原因物質を効果的に除去して、効率的に高濃度の次亜塩素酸ソーダを得ることができる次亜塩素酸ソーダの製造方法及び次亜塩素酸ソーダの製造装置を提供することができるようになった。 As described above, according to the present invention, scale-causing substances are effectively removed from desalted and concentrated water derived from high-salt-containing wastewater, while suppressing production costs, and high-concentration hypochlorous acid is efficiently obtained. It has become possible to provide a method for producing sodium hypochlorite and an apparatus for producing sodium hypochlorite from which soda can be obtained.
以下、本発明の次亜塩素酸ソーダの製造方法及び次亜塩素酸ソーダの製造装置を説明する。 Hereinafter, the manufacturing method of sodium hypochlorite and the manufacturing apparatus of sodium hypochlorite of this invention are demonstrated.
図１（ａ）には、焼却残渣等を埋め立てた一般廃棄物最終処分場で生じる高塩類含有浸出水から次亜塩素酸ソーダ（以下、「滅菌剤」とも記す。）を生成するプロセスが示されている。 FIG. 1 (a) shows a process for producing sodium hypochlorite (hereinafter also referred to as “sterilizing agent”) from high salt-containing leachate generated at a general waste final disposal site where incineration residue or the like is landfilled. Has been.
本発明のように、脱塩濃縮水等、廃棄物由来の副生塩から生成される滅菌剤は、次亜塩素酸ソーダ（ＮａＣｌＯ）の他、次亜塩素酸カリウム（ＫＣｌＯ）が含まれるため、ＪＩＳ規格を満たすソーダ工業の製品とはならない。そのため廃棄物由来の副生塩から生成される滅菌剤のことを「エコ次亜塩素酸ソーダ(エコ次亜)」と称する。 As in the present invention, the sterilizing agent produced from the by-product salt derived from waste, such as desalted concentrated water, contains potassium hypochlorite (KClO) in addition to sodium hypochlorite (NaClO). It is not a product of soda industry that meets JIS standards. For this reason, the sterilant produced from the by-product salt derived from waste is referred to as “ecohypochlorous acid soda”.
埋立地で生じる浸出水は、浸出水貯留工程で浸出水調整池に貯留され、次に、例えばライムソーダ法等の沈殿法を用いた前置軟化処理工程で浸出水に含まれるマンガン、マグネシウム、カルシウム等の多価イオンが除去される。 The leachate generated in the landfill is stored in the leachate adjustment pond in the leachate storage step, and then manganese, magnesium, contained in the leachate in the pre-softening treatment step using a precipitation method such as the lime soda method, Multivalent ions such as calcium are removed.
前置軟化処理工程では全カルシウム濃度が２０ｍｇ／Ｌ以下に調整される。全カルシウム濃度とは、浸出水に含まれるカルシウムイオン、溶解して未解離のカルシウム塩等を含む全てのカルシウムの濃度である。 In the pre-softening treatment step, the total calcium concentration is adjusted to 20 mg / L or less. The total calcium concentration is the concentration of all calcium including calcium ions contained in the leachate, dissolved and undissociated calcium salts, and the like.
ライムソーダ法とは、アルカリ領域となるようにｐＨを調整した浸出水に炭酸ソーダを注入し、浸出水に含まれるカルシウムイオンを炭酸カルシウムとして沈殿除去する方法である。 The lime soda method is a method in which sodium carbonate is poured into leachate whose pH is adjusted to be in the alkaline region, and calcium ions contained in the leachate are precipitated and removed as calcium carbonate.
前置軟化処理工程の後に接触酸化法による生物処理工程が実行され、生物処理された浸出水は凝集膜分離工程で凝集剤が添加された後に膜ろ過されて固形分が除去される。生物処理工程は好気処理や嫌気処理を組み合わせた硝化脱窒プロセス等公知の生物処理が採用される。 After the pre-softening treatment step, a biological treatment step by a catalytic oxidation method is performed, and the biologically treated leachate is filtered through a membrane after a flocculant is added in the agglomeration membrane separation step to remove solids. As the biological treatment process, a known biological treatment such as a nitrification denitrification process combining aerobic treatment and anaerobic treatment is adopted.
さらに活性炭吸着処理工程でＣＯＤ成分や着色成分等が除去され、キレート吸着処理工程で被処理水中の水銀や鉛等の重金属類が除去された後に、例えば電気透析装置を用いた脱塩処理工程が実行される。 Further, after the COD component, coloring component, etc. are removed in the activated carbon adsorption treatment process, and heavy metals such as mercury and lead in the water to be treated are removed in the chelate adsorption treatment step, a desalination treatment process using, for example, an electrodialyzer is performed. Executed.
脱塩処理工程で脱塩された被処理水は河川等に放流され、脱塩処理工程で濃縮された脱塩濃縮水に本発明の次亜塩素酸ソーダの製造方法が適用されて次亜塩素酸ソーダが製造される。当該次亜塩素酸ソーダは、脱塩処理工程で脱塩された被処理水を河川等に放流する前に滅菌処理するために用いることも可能になる。 The treated water desalted in the desalination treatment process is discharged into rivers, etc., and the method for producing sodium hypochlorite of the present invention is applied to the desalted concentrated water concentrated in the desalination treatment process. Acid soda is produced. The sodium hypochlorite can also be used to sterilize the water to be treated, which has been desalted in the desalination treatment step, before discharging it into a river or the like.
つまり、脱塩処理工程で濃縮された脱塩濃縮水が高塩類含有廃水由来の脱塩濃縮水となる。前置軟化処理工程では、脱塩処理工程を経た脱塩濃縮水の全カルシウム濃度が１００ｍｇ／Ｌになるように軟化処理が実行される。 That is, the desalted concentrated water concentrated in the desalting treatment step becomes desalted concentrated water derived from high salt-containing wastewater. In the pre-softening process, the softening process is performed so that the total calcium concentration of the desalted concentrated water that has passed through the desalting process is 100 mg / L.
本発明が適用される高塩類含有廃水由来の脱塩濃縮水は、上述の処理と全く同じ処理を経たものである必要はなく、脱塩処理工程で電気透析法以外の例えば逆浸透膜法等の他の方法が用いられて得られた脱塩濃縮水でもよい。 The desalted and concentrated water derived from high-salt-containing wastewater to which the present invention is applied need not be subjected to exactly the same treatment as described above, and other than the electrodialysis method in the desalination treatment step, such as a reverse osmosis membrane method Desalted concentrated water obtained by using other methods may be used.
また、高塩類含有廃水由来の脱塩濃縮水として、高塩類含有浸出水の脱塩濃縮水以外に、都市ごみ焼却炉や溶融炉に備えた湿式排ガス処理装置で生じる洗煙排水や、乾式二段バグフィルタの後段側のナトリウム系脱塩剤噴霧残渣等の高塩類含有廃水を濃縮処理した脱塩濃縮水であっても本発明を適用することができる。 In addition to desalted and concentrated water derived from high-salt-containing wastewater, in addition to desalted and concentrated water containing high-salt-containing leachate, smoke-washed wastewater generated in wet waste gas treatment equipment in municipal waste incinerators and melting furnaces, The present invention can be applied to desalted concentrated water obtained by concentrating high salt-containing wastewater such as a sodium-based desalting agent spray residue on the rear side of the stage bag filter.
本発明による次亜塩素酸ソーダの製造方法は、脱塩処理工程で得られた高塩類含有廃水由来の脱塩濃縮水を所定の塩素イオン濃度を示す不飽和状態で軟化処理してカルシウム濃度を低下させる軟化処理工程と、軟化処理工程で軟化処理された脱塩濃縮水から、イオン交換膜法を用いて苛性ソーダと塩素ガスを生成する電解工程と、電解工程で生成された苛性ソーダと塩素ガスとから次亜塩素酸ソーダを合成する次亜塩素酸ソーダ合成工程とを備えている。 In the method for producing sodium hypochlorite according to the present invention, the desalted concentrated water derived from the high-salt-containing wastewater obtained in the desalting treatment step is softened in an unsaturated state having a predetermined chlorine ion concentration to reduce the calcium concentration. A softening treatment step for reducing, an electrolysis step for producing caustic soda and chlorine gas from the desalted concentrated water softened in the softening treatment step using an ion exchange membrane method, and caustic soda and chlorine gas produced in the electrolysis step A sodium hypochlorite synthesizing step for synthesizing sodium hypochlorite.
飽和濃縮水ではなく所定の塩素イオン濃度を示す不飽和状態の脱塩濃縮水を用いることにより、飽和濃縮水を得るための乾燥塩の添加工程を不要とし、そのための溶解槽等の設備コストや薬剤コストの低減を図ることができる。 By using desalted concentrated water in an unsaturated state that shows a predetermined chloride ion concentration instead of saturated concentrated water, the addition process of dry salt to obtain saturated concentrated water is unnecessary, and equipment costs such as a dissolution tank for that purpose The cost of medicine can be reduced.
脱塩濃縮水が最終処分場の浸出水を脱塩処理して得られる脱塩濃縮水であり、所定の塩素イオン濃度が８００００ｍｇ／Ｌ以上の脱塩濃縮水であることが、イオン交換膜法を用いた電解工程を安定的に継続して実行できるという観点で好ましい。 The ion-exchange membrane method wherein the desalted concentrated water is desalted concentrated water obtained by desalting leachate from the final disposal site, and is a desalted concentrated water having a predetermined chlorine ion concentration of 80000 mg / L or more. It is preferable from the viewpoint that the electrolysis process using can be carried out stably and continuously.
脱塩濃縮水は塩素イオン濃度が５０００ｍｇ／Ｌ以上の最終処分場の浸出水を脱塩処理して得られる脱塩濃縮水であることが好ましく、適切に脱塩しながら、塩素イオン濃度が８００００ｍｇ／Ｌ以上の脱塩濃縮水に濃縮処理できるようになる。 The desalted concentrated water is preferably desalted concentrated water obtained by desalting the leachate from the final disposal site having a chlorine ion concentration of 5000 mg / L or more, and the chloride ion concentration is 80000 mg while appropriately desalting. / L or more demineralized concentrated water can be concentrated.
脱塩濃縮水は塩素イオン濃度が５０００〜１５０００ｍｇ／Ｌの最終処分場の浸出水を電気透析法で脱塩処理して得られる脱塩濃縮水であり、この範囲であれば効率的に塩素イオン濃度が８００００〜１０００００ｍｇ／Ｌの脱塩濃縮水を得ることができる。 Desalinated concentrated water is desalted concentrated water obtained by desalting the leachate from the final disposal site with a chloride ion concentration of 5000 to 15000 mg / L by electrodialysis, and if it is within this range, the chlorine ion is efficiently Desalted concentrated water having a concentration of 80,000 to 100,000 mg / L can be obtained.
脱塩濃縮水を塩素イオン濃度が所定の塩素イオン濃度未満のときに、原料塩を添加して塩素イオン濃度を所定の塩素イオン濃度以上に調整する塩素イオン濃度調整工程を備えていることが好ましい。 It is preferable to provide a chlorine ion concentration adjusting step for adjusting the chlorine ion concentration to a predetermined chlorine ion concentration or higher by adding a raw salt when the desalted concentrated water has a chlorine ion concentration lower than the predetermined chlorine ion concentration. .
塩素イオン濃度が所定の塩素イオン濃度未満の脱塩濃縮水であれば、イオン交換膜法を用いた電解工程の実行中に、脱塩濃縮水中の塩素イオンのほとんどが塩素ガスとなって電気伝導度が低下し、イオン交換膜の損傷を来す虞がある。そこで、脱塩濃縮水の塩素イオン濃度が所定の塩素イオン濃度に満たない場合にのみ原料塩を添加すれば、また乾燥塩の必要量も大きく低減でき、製造コストを効果的に低減できるようになる。 If the desalted and concentrated water has a chloride ion concentration less than the specified chloride ion concentration, most of the chloride ions in the desalted and concentrated water are converted into chlorine gas during the electrolysis process using the ion-exchange membrane method. There is a risk that the ion exchange membrane will be damaged. Therefore, if the raw material salt is added only when the chlorine ion concentration of the desalted concentrated water is less than the predetermined chlorine ion concentration, the necessary amount of dry salt can be greatly reduced, and the production cost can be effectively reduced. Become.
電解工程では、イオン交換膜が隔壁として配置された電解槽の一方に陽極が配置され他方に陰極が配置された隔膜電解装置が用いられる。陽極側に軟化処理された脱塩濃縮水が供給され陰極側に純水または軟化処理された水道水が供給されることにより、陽極側で塩素が生成され陰極側で苛性ソーダが生成される。 In the electrolysis process, a diaphragm electrolysis apparatus is used in which an anode is disposed on one side of an electrolytic cell in which an ion exchange membrane is disposed as a partition and a cathode is disposed on the other. By supplying desalted and concentrated water softened to the anode side and pure water or tap water softened to the cathode side, chlorine is produced on the anode side and caustic soda is produced on the cathode side.
電解工程で生成された塩素と苛性ソーダとを原料にして次亜塩素酸ソーダ合成工程で合成反応が促進されて次亜塩素酸ソーダが得られる。 By using chlorine and caustic soda produced in the electrolysis process as raw materials, the synthesis reaction is promoted in the sodium hypochlorite synthesis process to obtain sodium hypochlorite.
図１（ｂ）に示すように、軟化処理工程は、脱塩濃縮水に対して沈殿法でカルシウム濃度を低下させる第１軟化処理工程と、第１軟化処理工程の後にキレート吸着法でカルシウム濃度をさらに低下させる第２軟化処理工程を含む。 As shown in FIG. 1 (b), the softening treatment step includes a first softening treatment step for reducing the calcium concentration by a precipitation method with respect to desalted concentrated water, and a calcium concentration by a chelate adsorption method after the first softening treatment step. A second softening treatment step for further lowering.
図１（ｂ）には、沈殿法としてライムソーダ法が採用された例が示されている。当該第１軟化処理工程では、脱塩濃縮水をｐＨ１０以上に調整するｐＨ調整工程と、脱塩濃縮水に含有するカルシウム濃度に対して理論値より多い２〜１０モルの炭酸ソーダを注入する炭酸ソーダ注入工程と、塩化第二鉄のような無機系の凝集剤を添加する無機系凝集剤添加工程と、さらに有機系凝集剤を助剤として添加する有機系凝集剤添加工程とが実行される。
FIG. 1 (b) shows an example in which the lime soda method is employed as the precipitation method. In the first softening treatment step, a pH adjustment step of adjusting the desalted concentrated water to
この様な構成を採用すると、高塩類含有廃水由来の脱塩濃縮水に対して、先ず沈殿法でカルシウム濃度を低下させた後に、キレート吸着法でさらにカルシウム濃度を低下させることができるので、高価なキレートを長期に渡り機能させることができ、長時間にわたって電解工程を継続させることが可能になる。従って、安価で高濃度の次亜塩素酸ソーダを得ることができるようになる。 When such a configuration is adopted, since the calcium concentration can be reduced by the chelate adsorption method after the calcium concentration is first reduced by the precipitation method with respect to the desalted concentrated water derived from the wastewater containing high salt, it is expensive. As a result, it is possible to allow a long chelate to function for a long time, and to continue the electrolysis process for a long time. Accordingly, it is possible to obtain an inexpensive and high concentration sodium hypochlorite.
図１（ｂ）の例では、脱塩濃縮水のｐＨを高アルカリ状態に調整して炭酸ソーダを過剰気味に注入することによって、効果的に脱塩濃縮水中のカルシウム濃度を低下させることができるようになるという本願発明者らの新知見に基づき、第１軟化処理工程では、脱塩濃縮水をｐＨ１０以上に調整し、炭酸ソーダを脱塩濃縮水のカルシウム濃度に対して２〜１０モル、理論値（１モル）より過剰気味に注入することにより、前置軟化処理工程の後の脱塩濃縮水に主にイオンとして含有されるカルシウムと炭酸ソーダとの反応を促進させることができるようになる。
In the example of FIG. 1B, the calcium concentration in the desalted concentrated water can be effectively reduced by adjusting the pH of the desalted concentrated water to a high alkaline state and injecting sodium carbonate excessively. Based on the new knowledge of the inventors of the present application, the desalted and concentrated water is adjusted to
図２には、脱塩処理工程に用いられる電気透析装置が組み込まれた脱塩処理装置が示されている。脱塩処理装置は、前後２段設けられた第１電気透析装置及び第２電気透析装置を備えている。電気透析装置は、塩水を供給しながら電極間に直流電圧を印加したときに、電位差により陽イオンが陰極側に移動し、陰イオンが陽極側に移動する現象を利用して脱塩する装置である。薬液タンクに充填された硝酸によりｐＨ調整された硝酸ナトリウムである電解液が電解液槽から電気透析装置の各電極に循環供給される。 FIG. 2 shows a desalting apparatus incorporating an electrodialyzer used in the desalting process. The desalting apparatus includes a first electrodialysis apparatus and a second electrodialysis apparatus provided in two stages. An electrodialysis device is a device that desalinates by utilizing the phenomenon that when a DC voltage is applied between electrodes while supplying salt water, a cation moves to the cathode side due to a potential difference and an anion moves to the anode side. is there. An electrolytic solution, which is sodium nitrate adjusted in pH with nitric acid filled in the chemical solution tank, is circulated and supplied from the electrolytic solution tank to each electrode of the electrodialysis apparatus.
原水槽に貯留された脱塩原水は、フィルタを介して異物が除去された後に脱塩液槽、混合液槽、濃縮液槽にそれぞれバルブを介して導かれ、各液槽の塩素濃度差が適正な値に調整される。 The demineralized raw water stored in the raw water tank is guided to the desalted liquid tank, the mixed liquid tank, and the concentrated liquid tank through valves after removing foreign substances through the filter, and the chlorine concentration difference of each liquid tank It is adjusted to an appropriate value.
脱塩液槽から第１電気透析装置に循環供給される脱塩原水に含まれる塩素イオンが、混合液槽から第１電気透析装置に循環供給される混合液側に移動することにより脱塩され、所定の塩素イオン濃度に低下すると脱塩処理水として排水される。薬液槽から塩酸が混合液槽に供給されて混合液のｐＨが適正な値に調整される。 Chlorine ions contained in the desalted raw water circulated and supplied from the desalting solution tank to the first electrodialysis apparatus are desalted by moving from the mixture liquid tank to the mixed solution side circulated and supplied to the first electrodialysis apparatus. When it is reduced to a predetermined chlorine ion concentration, it is drained as desalted water. Hydrochloric acid is supplied from the chemical solution tank to the mixed solution tank, and the pH of the mixed solution is adjusted to an appropriate value.
混合液槽から第２電気透析装置に循環供給される脱塩原水に含まれる塩素イオンが、濃縮液槽から第２電気透析装置に循環供給される濃縮液側に移動することにより脱塩され、所定の塩素イオン濃度に低下すると原水槽に戻されて、再度第１電気透析装置で脱塩される。このようにして第２電気透析装置で濃縮された脱塩濃縮水が軟化処理工程に供給される。 Chlorine ions contained in the desalted raw water circulated and supplied from the mixed solution tank to the second electrodialysis apparatus are desalted by moving from the concentrate tank to the concentrate side circulated and supplied to the second electrodialysis apparatus, When it falls to a predetermined chlorine ion concentration, it is returned to the raw water tank and desalted again by the first electrodialyzer. In this way, the desalted and concentrated water concentrated by the second electrodialyzer is supplied to the softening process.
図２には、塩素イオン濃度１５０００ｍｇ／Ｌの脱塩原水が電気透析装置で脱塩処理されて２００ｍｇ／Ｌの脱塩処理水となり、塩素イオン濃度８００００ｍｇ／Ｌの脱塩濃縮水が得られることを示している。 FIG. 2 shows that desalted raw water having a chloride ion concentration of 15000 mg / L is desalted by an electrodialyzer to become 200 mg / L desalted water, and desalted concentrated water having a chloride ion concentration of 80000 mg / L is obtained. Is shown.
図３に示すように、次亜塩素酸ソーダの製造装置は、電気透析装置で脱塩処理された脱塩濃縮水を、飽和処理することなく所定の塩素イオン濃度を示す不飽和状態で軟化処理してカルシウム濃度を低下させる軟化処理装置と、軟化処理装置で軟化処理された脱塩濃縮水から、イオン交換膜法を用いて苛性ソーダと塩素ガスを生成する隔膜電解装置と、隔膜電解装置で生成された苛性ソーダ（ＮａＯＨ）と塩素ガス（Ｃｌ２）とから次亜塩素酸ソーダ（ＮａＣｌＯ）を合成する反応槽を備えた次亜塩素酸ソーダ合成装置とから構成されている。 As shown in FIG. 3, the sodium hypochlorite manufacturing apparatus softens the desalted concentrated water desalted by the electrodialyzer in an unsaturated state that shows a predetermined chloride ion concentration without being saturated. Produced by a membrane electrolyzer that generates caustic soda and chlorine gas using a ion exchange membrane method from a softening treatment device that lowers the calcium concentration and demineralized concentrated water softened by the softening treatment device. It comprises a sodium hypochlorite synthesizer equipped with a reaction tank for synthesizing sodium hypochlorite (NaClO) from the produced caustic soda (NaOH) and chlorine gas (Cl 2 ).
そして、軟化処理装置は、脱塩濃縮水に対して沈殿法でカルシウム濃度を低下させる第１軟化処理装置と、第１軟化処理装置の後にキレート吸着法でカルシウム濃度を１ｍｇ／Ｌ以下に低下させる第２軟化処理装置とで構成されている。 And a softening processing apparatus reduces a calcium concentration to 1 mg / L or less by a chelate adsorption method after a 1st softening processing apparatus and the 1st softening processing apparatus which lowers a calcium concentration with respect to desalted concentrated water. It is comprised with the 2nd softening processing apparatus.
脱塩濃縮水の塩素イオン濃度が所定の塩素イオン濃度未満であると、隔膜電解装置に投入された脱塩濃縮水中の塩素イオンのほとんどが塩素ガスとなって電気伝導度が低下し、イオン交換膜の損傷を来す虞がある。 If the chlorine ion concentration in the desalted and concentrated water is less than the prescribed chloride ion concentration, most of the chlorine ions in the desalted and concentrated water that has been put into the diaphragm electrolyzer will become chlorine gas, resulting in a decrease in electrical conductivity and ion exchange. There is a risk of film damage.
そのため、電気透析装置と軟化処理装置との間に原水槽を備え、脱塩濃縮水の塩素イオン濃度が所定の塩素イオン濃度未満のときに、軟化処理装置に供給する脱塩濃縮水に原料塩を添加して塩素イオン濃度を所定の塩素イオン濃度以上に調整するように構成されていることが好ましい。 Therefore, a raw water tank is provided between the electrodialysis device and the softening treatment device, and when the chlorine ion concentration of the desalted concentrated water is less than a predetermined chlorine ion concentration, the raw salt is supplied to the desalted concentrated water supplied to the softening treatment device. It is preferable that the chlorine ion concentration is adjusted to a predetermined chlorine ion concentration or more by adding.
脱塩濃縮水の塩素イオン濃度が所定の塩素イオン濃度に満たない場合にのみ原料塩を添加して撹拌すれば、常時飽和濃縮水とする場合に比べて、乾燥塩の必要量も大きく低減でき、製造コストを効果的に低減できるようになる。 If the raw material salt is added and stirred only when the chlorine ion concentration of the desalted concentrated water is less than the prescribed chlorine ion concentration, the required amount of dry salt can be greatly reduced compared to the case of using a saturated concentrated water constantly. The manufacturing cost can be effectively reduced.
そのため、原水槽には塩素イオン濃度調整装置として、電気伝導度計ＥＣ、モータＭで駆動される撹拌羽根、原料塩投入機構が設けられている。電気伝導度に基づいて塩素イオン濃度が推定される。 Therefore, the raw water tank is provided with an electrical conductivity meter EC, a stirring blade driven by a motor M, and a raw material salt charging mechanism as a chlorine ion concentration adjusting device. The chloride ion concentration is estimated based on the electrical conductivity.
電気伝導度計ＥＣによって計測された塩素イオン濃度に基づいて、原水槽から軟化処理装置に脱塩濃縮水を供給するポンプを制御する制御部が設けられ、塩素イオン濃度が所定の塩素イオン濃度に満たない場合には制御部によってポンプ停止され、原料塩投入機構によって塩素イオン濃度が調整されるように構成されている。 Based on the chlorine ion concentration measured by the electrical conductivity meter EC, a control unit is provided for controlling a pump that supplies demineralized concentrated water from the raw water tank to the softening treatment device, so that the chlorine ion concentration becomes a predetermined chlorine ion concentration. When it is not satisfied, the pump is stopped by the control unit, and the chlorine ion concentration is adjusted by the raw material salt charging mechanism.
つまり、当該ポンプと制御部によって、脱塩濃縮水の塩素イオン濃度が所定の塩素イオン濃度未満のときに、脱塩濃縮水の塩素イオン濃度が所定の塩素イオン濃度以上になるまで脱塩濃縮水の軟化処理装置への供給を停止する供給停止機構となる。 That is, when the chlorine ion concentration of the desalted concentrated water is less than the predetermined chlorine ion concentration, the desalted concentrated water is reduced by the pump and the control unit until the chlorine ion concentration of the desalted concentrated water becomes equal to or higher than the predetermined chlorine ion concentration. It becomes a supply stop mechanism which stops supply to the softening processing apparatus.
軟化処理装置で軟化処理された脱塩濃縮水は隔膜電解装置の電解槽の陽極側に定量供給され、純水槽に貯留された純水は隔膜電解装置の電解槽の陰極側に投入される。隔膜電解装置の陽極及び陰極に整流器から電解用の電圧が印加されて電解処理が促進される。 The desalted and concentrated water softened by the softening apparatus is supplied in a fixed amount to the anode side of the electrolytic cell of the diaphragm electrolyzer, and the pure water stored in the pure water tank is supplied to the cathode side of the electrolytic cell of the diaphragm electrolyzer. A voltage for electrolysis is applied from the rectifier to the anode and the cathode of the diaphragm electrolysis apparatus to promote the electrolysis process.
本発明による次亜塩素酸ソーダの製造方法は、高塩類含有廃水由来の脱塩濃縮水のカルシウム濃度を低下させる前置軟化処理工程と、生物処理工程と、凝集沈殿処理工程と、砂ろ過処理工程と、活性炭吸着処理工程と、キレート吸着処理工程とからなる群から選ばれる１以上の処理工程または２以上の処理工程の組合せからなる前処理工程を備え、その後に軟化処理工程が実行されるように構成されていることが好ましい。 The method for producing sodium hypochlorite according to the present invention comprises a pre-softening treatment step, a biological treatment step, a coagulation sedimentation treatment step, and a sand filtration treatment for reducing the calcium concentration of desalted concentrated water derived from high salt-containing wastewater. A pretreatment step comprising one or more treatment steps selected from the group consisting of a step, an activated carbon adsorption treatment step, and a chelate adsorption treatment step, or a combination of two or more treatment steps, followed by a softening treatment step. It is preferable that it is comprised.
以下に本発明の実施例を説明する。
ある市の一般廃棄物最終処分場の浸出水に対して、図１（ａ）に示す工程に基づいて得た脱塩濃縮水の実液と、同じ工程で得た脱塩濃縮水に乾燥塩を添加して最も電解条件の良い飽和濃縮水の双方で電解性能の比較を行なった。どちらの原水も図１（ｂ）に示す第１軟化処理でカルシウム濃度を１０ｍｇ／Ｌ以下に、第２軟化処理でカルシウム濃度を隔膜電解法に必要な２００μｇ／Ｌ以下にまで下げた。
Examples of the present invention will be described below.
For the leachate of a municipal waste final disposal site in a city, dry salt is added to the desalted concentrated water obtained based on the process shown in FIG. 1 (a) and the desalted concentrated water obtained in the same process. The electrolysis performance was compared for both saturated concentrated water with the best electrolysis conditions. In both raw waters, the calcium concentration was lowered to 10 mg / L or less by the first softening treatment shown in FIG. 1B, and the calcium concentration was lowered to 200 μg / L or less necessary for the diaphragm electrolysis by the second softening treatment.
図４（ａ）には、脱塩濃縮水と飽和濃縮水の性状が示されている。脱塩濃縮水のＮａＣｌ濃度は１２８ｇ／Ｌ、電気伝導度（以下、「ＥＣ」と記す。)は１８．３Ｓ／ｍであり、乾燥塩を溶解させた飽和濃縮水のＮａＣｌ濃度は３１０ｇ／Ｌ、ＥＣは２７．８Ｓ／ｍであった。 FIG. 4A shows the properties of desalted concentrated water and saturated concentrated water. The NaCl concentration of the desalted concentrated water is 128 g / L, the electric conductivity (hereinafter referred to as “EC”) is 18.3 S / m, and the NaCl concentration of the saturated concentrated water in which the dry salt is dissolved is 310 g / L. EC was 27.8 S / m.
図３に示す隔膜電解装置を用いて滅菌剤を生成した。既に説明したように、隔膜電解装置は電解槽と整流器から構成される。電解槽内はイオン交換膜で陰極室と陽極室の２室に仕切られている。陰極側には純水を、陽極側には前処理した濃縮水を送水する。純水は、水道水を純水器(ミリポア製Milli-Q IntegralMT)で処理したものを用いた。 A sterilant was produced using the diaphragm electrolysis apparatus shown in FIG. As already explained, the diaphragm electrolysis apparatus is composed of an electrolytic cell and a rectifier. The inside of the electrolytic cell is divided into two chambers, a cathode chamber and an anode chamber, by an ion exchange membrane. Pure water is sent to the cathode side and pretreated concentrated water is sent to the anode side. As pure water, tap water treated with a pure water device (Millipore Milli-Q IntegralMT) was used.
陰極では、純水と陽極側からイオン交換膜を通過したナトリウムイオンが反応し苛性ソーダと水素ガスが生成される。水素ガスは脱気槽で大気開放し苛性ソーダが収集される。陽極では濃縮水が電気分解され塩素ガスと淡塩水が生成される。エコ次亜は、収集した苛性ソーダと塩素ガスを反応槽で混合して生成する。実験条件は、純水の送液量１８０ｍＬ／ｈｒ、濃縮水の送液量１２０ｍＬ／ｈｒ、電極間の電流密度１．５ｋＡ／ｍ２である。電解電圧、有効塩素濃度および電流効率を確認した。 At the cathode, pure water and sodium ions that have passed through the ion exchange membrane from the anode side react to generate caustic soda and hydrogen gas. Hydrogen gas is released to the atmosphere in a deaeration tank and caustic soda is collected. At the anode, the concentrated water is electrolyzed to produce chlorine gas and fresh salt water. Eco HYKO is produced by mixing collected caustic soda and chlorine gas in a reaction tank. The experimental conditions are a pure water feed rate of 180 mL / hr, a concentrated water feed rate of 120 mL / hr, and a current density between electrodes of 1.5 kA / m 2 . Electrolytic voltage, effective chlorine concentration and current efficiency were confirmed.
図５には、脱塩濃縮水と飽和濃縮水の電解電圧が示されている。電解電圧は、イオン交換膜のスケーリングの状況を示す指標である。脱塩濃縮水の電解電圧は５．５Ｖ程度、一方、飽和濃縮水は４．９Ｖ程度となり、脱塩濃縮水の方が０．６Ｖ程電解電圧は高くなった。しかし、共に電圧上昇はほとんどなく、約２週間安定して運転できた。 FIG. 5 shows the electrolysis voltage of desalted concentrated water and saturated concentrated water. The electrolytic voltage is an index indicating the state of scaling of the ion exchange membrane. The electrolytic voltage of the desalted concentrated water was about 5.5V, while the saturated concentrated water was about 4.9V, and the electrolytic voltage of the desalted concentrated water was about 0.6V higher. However, there was almost no voltage increase in both cases, and the operation was stable for about 2 weeks.
図４（ｂ）には、脱塩濃縮水と飽和濃縮水それぞれから得られたエコ次亜の有効塩素濃度が示されている。淡塩水混合時の脱塩濃縮水の有効塩素濃度は３．２％、飽和濃縮水は４．５％となった。脱塩濃縮水の方が飽和濃縮水よりも有効塩素濃度は低くなったが、原水の塩素濃度差程の差は生じなかった。 FIG. 4B shows the effective hypochlorous chlorine concentration obtained from each of the desalted concentrated water and the saturated concentrated water. The effective chlorine concentration of the desalted and concentrated water during mixing with the fresh salt water was 3.2%, and the saturated concentrated water was 4.5%. The desalted and concentrated water had a lower effective chlorine concentration than the saturated and concentrated water, but there was no difference in the chlorine concentration difference of the raw water.
図４（ｃ）には、脱塩濃縮水と飽和濃縮水の電流効率が示されている。電流効率は、電気分解により理論的に生成される有効塩素量と実際に生成された有効塩素量の割合である。脱塩濃縮水は１時間当たり９．６ｇの有効塩素が生成され、電流効率は４８．４％となった。一方、飽和濃縮水の電流効率は６１．０％となり、脱塩濃縮水の方が１２．６ポイント電流効率は低くなったが、約５０％の電流効率を確保できた。尚、理論有効塩素量は１９．８４ｇ／ｈｒ（＝１５（Ａ）×３６００（ｓ）／９６５００（Ｃ・ｍｏｌ−１）×３５．４５（ｇ／ｍｏｌ）である。 FIG. 4C shows the current efficiency of desalted concentrated water and saturated concentrated water. Current efficiency is the ratio between the amount of effective chlorine theoretically generated by electrolysis and the amount of effective chlorine actually generated. The desalted concentrated water produced 9.6 g of effective chlorine per hour, and the current efficiency was 48.4%. On the other hand, the current efficiency of the saturated concentrated water was 61.0%, and the current efficiency of the desalted concentrated water was 12.6 points lower, but a current efficiency of about 50% could be secured. The theoretical effective chlorine content is 19.84 g / hr (= 15 (A) × 3600 (s) / 96500 (C · mol −1 ) × 35.45 (g / mol).
図６には、脱塩濃縮水と飽和濃縮水それぞれから得られたエコ次亜の製造コスト試算値が示されている。原料塩費は脱塩濃縮水を飽和するのに必要な乾燥塩の費用、薬品費は炭酸ソーダなど第１軟化処理で使用する薬品の費用、キレート樹脂費は第２軟化処理で使用するキレート樹脂交換費用、電力費は隔膜電解に必要な電力の費用のことである。 FIG. 6 shows estimated production costs of Eco Hypo-A obtained from desalted concentrated water and saturated concentrated water, respectively. The raw material salt cost is the cost of dry salt required to saturate the desalted concentrated water, the chemical cost is the cost of chemicals used in the first softening treatment such as sodium carbonate, and the chelate resin cost is the chelating resin used in the second softening treatment The replacement cost and the power cost are the power costs required for diaphragm electrolysis.
試算の結果、エコ次亜１ｍ３当たりの生成費は、脱塩濃縮水は５，１５０円／ｍ３、飽和濃縮水は１０，０５０円／ｍ３となり、脱塩濃縮水をそのまま隔膜電解する方が安価になることが判明した。また有効塩素１ｋｇ当たりのエコ次亜生成費も同じ結果になった。飽和濃縮水は、電力費が安価になるもののそれ以上に原料塩費が嵩み、結果割高になることが判明した。 Results of calculations, generation costs eco hypophosphorous 1 m 3 per is desalted retentate 5,150 yen / m 3, saturated retentate as it is membrane electrolysis 10,050 yen / m 3, and the desalting concentrate Turned out to be cheaper. In addition, the cost of eco hypochlorite production per kg of available chlorine was the same. Saturated concentrated water has been found to have a higher cost of raw material salt and a higher cost as a result, although the power cost is lower.
上述した実施形態は本発明の一態様の説明に過ぎず、該記載により本発明の技術的範囲が限定されるものではなく、各プロセスに用いられる装置の構造や添加される試薬の種類や量は本発明の作用効果が奏される範囲で適宜変更設計可能であることはいうまでもない。 The above-described embodiment is merely an explanation of one aspect of the present invention, and the technical scope of the present invention is not limited by the description. The structure of the apparatus used in each process and the type and amount of reagent to be added Needless to say, can be appropriately modified within the range in which the effects of the present invention can be achieved.
Claims (13)
前記軟化処理工程で軟化処理された脱塩濃縮水から、イオン交換膜法を用いて苛性ソーダと塩素ガスを生成する電解工程と、
前記電解工程で生成された苛性ソーダと塩素ガスとから次亜塩素酸ソーダを合成する次亜塩素酸ソーダ合成工程とを備え、
前記軟化処理工程は、脱塩濃縮水に対して沈殿法でカルシウム濃度を低下させる第１軟化処理工程と、前記第１軟化処理工程の後にキレート吸着法でカルシウム濃度をさらに低下させる第２軟化処理工程を含む、
ことを特徴とする次亜塩素酸ソーダの製造方法。 A softening treatment step of softening a desalted concentrated water derived from high salt-containing wastewater in an unsaturated state having a predetermined chloride ion concentration to lower the calcium concentration;
An electrolysis process for producing caustic soda and chlorine gas from the desalted concentrated water softened in the softening process using an ion exchange membrane method;
A sodium hypochlorite synthesis step for synthesizing sodium hypochlorite from caustic soda and chlorine gas generated in the electrolysis step,
The softening treatment step includes a first softening treatment step in which the calcium concentration is reduced by a precipitation method with respect to desalted concentrated water, and a second softening treatment in which the calcium concentration is further reduced by a chelate adsorption method after the first softening treatment step. Including steps,
A method for producing sodium hypochlorite, characterized in that
前記軟化処理装置で軟化処理された脱塩濃縮水から、イオン交換膜法を用いて苛性ソーダと塩素ガスを生成する電解装置と、
前記電解装置で生成された苛性ソーダと塩素ガスとから次亜塩素酸ソーダを合成する次亜塩素酸ソーダ合成装置とを備え、
前記軟化処理装置は、脱塩濃縮水に対して沈殿法でカルシウム濃度を低下させる第１軟化処理装置と、前記第１軟化処理装置の後にキレート吸着法でカルシウム濃度を低下させる第２軟化処理装置を含む、
ことを特徴とする次亜塩素酸ソーダの製造装置。 A softening treatment device for softening a desalted concentrated water derived from high salt-containing wastewater in an unsaturated state having a predetermined chloride ion concentration to lower the calcium concentration;
An electrolyzer that generates caustic soda and chlorine gas from the desalted and concentrated water softened by the softening device using an ion exchange membrane method;
A sodium hypochlorite synthesizer for synthesizing sodium hypochlorite from caustic soda and chlorine gas generated in the electrolysis apparatus,
The softening device includes a first softening device that lowers the calcium concentration by a precipitation method with respect to desalted concentrated water, and a second softening device that lowers the calcium concentration by a chelate adsorption method after the first softening device. including,
An apparatus for producing sodium hypochlorite, characterized in that.
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