JP2024021812A - Treatment method for solution containing alkali sulfides - Google Patents
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- 239000003513 alkali Substances 0.000 title claims abstract description 153
- 238000000034 method Methods 0.000 title claims abstract description 80
- 150000003568 thioethers Chemical class 0.000 title 1
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 175
- 230000003647 oxidation Effects 0.000 claims abstract description 134
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 134
- 150000004763 sulfides Chemical class 0.000 claims abstract description 58
- 239000010802 sludge Substances 0.000 claims abstract description 55
- 150000003467 sulfuric acid derivatives Chemical class 0.000 claims abstract description 31
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 23
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims description 87
- 239000002351 wastewater Substances 0.000 claims description 24
- HYHCSLBZRBJJCH-UHFFFAOYSA-M sodium hydrosulfide Chemical compound [Na+].[SH-] HYHCSLBZRBJJCH-UHFFFAOYSA-M 0.000 claims description 13
- 230000001590 oxidative effect Effects 0.000 claims description 10
- RWSOTUBLDIXVET-UHFFFAOYSA-M hydrosulfide Chemical compound [SH-] RWSOTUBLDIXVET-UHFFFAOYSA-M 0.000 claims description 8
- 238000003672 processing method Methods 0.000 claims 1
- 239000007788 liquid Substances 0.000 abstract description 32
- 239000000243 solution Substances 0.000 description 84
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 27
- 239000007864 aqueous solution Substances 0.000 description 21
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 20
- 238000012360 testing method Methods 0.000 description 17
- 229910052979 sodium sulfide Inorganic materials 0.000 description 15
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 15
- WQOXQRCZOLPYPM-UHFFFAOYSA-N dimethyl disulfide Chemical compound CSSC WQOXQRCZOLPYPM-UHFFFAOYSA-N 0.000 description 14
- 239000007789 gas Substances 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 11
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 10
- 238000005406 washing Methods 0.000 description 10
- -1 NaSH and Na 2 S Chemical class 0.000 description 9
- IHYNKGRWCDKNEG-UHFFFAOYSA-N n-(4-bromophenyl)-2,6-dihydroxybenzamide Chemical compound OC1=CC=CC(O)=C1C(=O)NC1=CC=C(Br)C=C1 IHYNKGRWCDKNEG-UHFFFAOYSA-N 0.000 description 9
- 235000011121 sodium hydroxide Nutrition 0.000 description 9
- DHCDFWKWKRSZHF-UHFFFAOYSA-L thiosulfate(2-) Chemical compound [O-]S([S-])(=O)=O DHCDFWKWKRSZHF-UHFFFAOYSA-L 0.000 description 9
- 239000002699 waste material Substances 0.000 description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 8
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 8
- 229910000029 sodium carbonate Inorganic materials 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 239000012085 test solution Substances 0.000 description 7
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 238000000354 decomposition reaction Methods 0.000 description 6
- 244000005700 microbiome Species 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 5
- 239000001569 carbon dioxide Substances 0.000 description 5
- 229910002092 carbon dioxide Inorganic materials 0.000 description 5
- 238000005336 cracking Methods 0.000 description 5
- 238000011156 evaluation Methods 0.000 description 5
- 229940006280 thiosulfate ion Drugs 0.000 description 5
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- VDQVEACBQKUUSU-UHFFFAOYSA-M disodium;sulfanide Chemical compound [Na+].[Na+].[SH-] VDQVEACBQKUUSU-UHFFFAOYSA-M 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000011734 sodium Substances 0.000 description 4
- 238000009279 wet oxidation reaction Methods 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000006386 neutralization reaction Methods 0.000 description 3
- 239000007800 oxidant agent Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical class [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- 238000004448 titration Methods 0.000 description 3
- 238000005273 aeration Methods 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 2
- 230000005764 inhibitory process Effects 0.000 description 2
- 230000000813 microbial effect Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 150000004045 organic chlorine compounds Chemical class 0.000 description 2
- 239000005416 organic matter Substances 0.000 description 2
- 239000012286 potassium permanganate Substances 0.000 description 2
- 238000000197 pyrolysis Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 125000004434 sulfur atom Chemical group 0.000 description 2
- 238000005979 thermal decomposition reaction Methods 0.000 description 2
- 150000004764 thiosulfuric acid derivatives Chemical class 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 239000007832 Na2SO4 Substances 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 238000005194 fractionation Methods 0.000 description 1
- 239000001963 growth medium Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000004255 ion exchange chromatography Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 238000006864 oxidative decomposition reaction Methods 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- WBHQBSYUUJJSRZ-UHFFFAOYSA-M sodium bisulfate Chemical compound [Na+].OS([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-M 0.000 description 1
- 229910000342 sodium bisulfate Inorganic materials 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 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
- 238000005987 sulfurization reaction Methods 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
- 238000003911 water pollution Methods 0.000 description 1
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- Treatment Of Water By Oxidation Or Reduction (AREA)
Abstract
Description
本発明は、水硫化アルカリや硫化アルカリ等の硫化アルカリ類を含有する溶液を酸化処理する硫化アルカリ類含有溶液の処理方法に関する。詳しくは、本発明は、酸化処理後の前記溶液を活性汚泥処理する硫化アルカリ類含有溶液の処理方法に関する。 The present invention relates to a method for treating an alkali sulfide-containing solution, in which a solution containing an alkali sulfide such as an alkali hydrosulfide or an alkali sulfide is oxidized. Specifically, the present invention relates to a method for treating an alkali sulfide-containing solution, in which the solution after oxidation treatment is treated with activated sludge.
ナフサの分解プロセスでは、ナフサ分解炉の長寿命化を目的として、原料ナフサにジメチルジスルフィド（ＤＭＤＳ）を添加して、熱分解している。添加されたＤＭＤＳは、ナフサ熱分解中に硫化水素（Ｈ２Ｓ）に変換される。このＨ２Ｓ含有ガスは、苛性ソーダ溶液により洗浄されることで、Ｈ２Ｓは水硫化ナトリウム（ＮａＳＨ）や硫化ナトリウム（Ｎａ２Ｓ）等の有害な還元性硫化物塩に変換され、洗浄廃水中に含有されて系外へ排出される。
これらの還元性硫化物塩を含む洗浄廃水は、ＣＯＤＭｎ濃度が高く、生物学的に害を及ぼすという理由や、該還元性硫化物塩は、廃液を活性汚泥処理する前の中和槽で、悪臭の原因となるＨ２Ｓを発生するため、それを防止するための対策が必要となるという理由から、湿式酸化処理により無害な硫酸塩等に変換することが行われている。
In the naphtha cracking process, dimethyl disulfide (DMDS) is added to raw material naphtha for thermal decomposition in order to extend the life of the naphtha cracking furnace. The added DMDS is converted to hydrogen sulfide (H 2 S) during naphtha pyrolysis. By washing this H 2 S-containing gas with a caustic soda solution, H 2 S is converted into harmful reducing sulfide salts such as sodium bisulfide (NaSH) and sodium sulfide (Na 2 S), and the washing wastewater is washed away. contained in it and discharged outside the system.
Washing wastewater containing these reducing sulfide salts has a high COD Mn concentration and is biologically harmful. Since H 2 S, which causes a bad odor, is generated, it is necessary to take measures to prevent this, and therefore, wet oxidation treatment is carried out to convert it into harmless sulfate and the like.
ＮａＳＨやＮａ２Ｓ等の還元性硫化物塩を湿式酸化処理する方法として、非特許文献１には、酸化剤として酸素又は空気を用いて湿式酸化処理する方法が開示されている。
また、特許文献１には、細孔容積総量を規定した活性炭の共存下、酸化剤として酸素又は酸素含有ガスを用いて、硫化アルカリを湿式酸化処理して無害なチオ硫酸ソーダに変換した後、廃液のｐＨを中性付近に調整した後、微生物処理する方法が開示されている。
また、非特許文献２には、空気又は酸素ガス以外の酸化剤として、過酸化水素を用いて、有機塩素化合物を湿式酸化処理する方法が開示されている。
As a method for wet oxidizing reducing sulfide salts such as NaSH and Na 2 S, Non-Patent Document 1 discloses a wet oxidizing method using oxygen or air as an oxidizing agent.
Furthermore, in Patent Document 1, in the presence of activated carbon with a defined total pore volume, oxygen or an oxygen-containing gas is used as an oxidizing agent to wet oxidize alkali sulfide to convert it into harmless sodium thiosulfate; A method is disclosed in which the pH of waste liquid is adjusted to around neutrality and then treated with microorganisms.
Further, Non-Patent Document 2 discloses a method of wet oxidizing an organic chlorine compound using hydrogen peroxide as an oxidizing agent other than air or oxygen gas.
しかしながら、非特許文献１に記載された方法では、被酸化物を１５０～３２０℃という高温で酸化処理する必要がある。特にエチレン廃ソーダを処理する場合、温度１８０～２２０℃、圧力３０～５０ｋｇ／ｃｍ２という高温高圧下で、酸化処理する必要があるため、工場設備（減価償却費等）や電力等のユーティリティー費用の面での経済的負担が大きいという課題がある。 However, in the method described in Non-Patent Document 1, it is necessary to oxidize the object to be oxidized at a high temperature of 150 to 320°C. In particular, when processing ethylene waste soda, it is necessary to perform oxidation treatment at a high temperature and pressure of 180 to 220°C and a pressure of 30 to 50 kg/ cm2 , which reduces the cost of factory equipment (depreciation, etc.) and utility costs such as electricity. There is a problem in that the economic burden is large.
特許文献１に記載された方法では、温度５０℃以上、好ましくは６０～１５０℃、圧力１～７気圧の範囲内で加熱して、湿式酸化処理することができるが、活性炭の劣化により湿式酸化の処理効率が徐々に低下するため、劣化した活性炭を、新しい活性炭に交換したり又は反応系内から取り出して賦活処理したりする必要がある。そのため、湿式酸化処理の操作性に劣るという課題や、メンテナンス費用の面での経済的負担が大きいという課題がある。 In the method described in Patent Document 1, wet oxidation treatment can be performed by heating at a temperature of 50°C or higher, preferably 60 to 150°C, and a pressure of 1 to 7 atm. However, due to deterioration of activated carbon, wet oxidation Since the treatment efficiency gradually decreases, it is necessary to replace the deteriorated activated carbon with new activated carbon or take it out from the reaction system and perform activation treatment. Therefore, there are problems in that the operability of wet oxidation treatment is poor and that the economic burden in terms of maintenance costs is large.
非特許文献２は、ＮａＳＨやＮａ２Ｓ等の還元性硫化物塩を酸化処理することについて何ら言及していないが、非特許文献２に記載された方法では、有機塩素化合物を温度１５０～１８０℃という高温で酸化処理する必要がある。また、酸化処理後の廃液を活性汚泥処理するときに、活性汚泥処理前の廃液中に過酸化水素が含まれると、過酸化水素が活性汚泥中の微生物を失活させるという課題もある（例えば、非特許文献３）。 Non-Patent Document 2 does not mention anything about oxidizing reducing sulfide salts such as NaSH and Na 2 S, but in the method described in Non-Patent Document 2, organic chlorine compounds are heated at a temperature of 150 to 180 ℃. It is necessary to perform oxidation treatment at a high temperature of ℃. Additionally, when the waste liquid after oxidation treatment is treated with activated sludge, if hydrogen peroxide is contained in the waste liquid before activated sludge treatment, there is also the problem that hydrogen peroxide deactivates microorganisms in the activated sludge (e.g. , Non-Patent Document 3).
本発明はこれらの問題点を解決することを目的とする。
すなわち、本発明は、硫化アルカリ類含有溶液の酸化処理で、活性汚泥処理が可能な処理液を得、この酸化処理液を、実質的に後処理することなく、活性汚泥処理することができる水硫化アルカリ含有溶液の処理方法を提供することを課題とする。
The present invention aims to solve these problems.
That is, the present invention obtains a treatment liquid that can be treated with activated sludge through oxidation treatment of an alkali sulfide-containing solution, and converts this oxidized treatment liquid into water that can be treated with activated sludge without substantially post-treatment. An object of the present invention is to provide a method for treating an alkali sulfide-containing solution.
本発明者らは、上記課題を解決すべく検討を重ねた結果、水硫化ナトリウム（ＮａＳＨ）や硫化ナトリウム（Ｎａ２Ｓ）を含有する廃液を、過酸化水素で酸化処理し、対応する硫酸塩類に変換することで、活性汚泥処理に先立ち、該廃液を中和する際の硫化水素の発生を抑制し、実質的に後処理することなく、活性汚泥処理に供することができることの知見を得、この知見に基づき本発明を完成させた。 As a result of repeated studies to solve the above problems, the present inventors oxidized waste liquid containing sodium hydrosulfide (NaSH) and sodium sulfide (Na 2 S) with hydrogen peroxide, and oxidized it to the corresponding sulfates. By converting to activated sludge, the generation of hydrogen sulfide when neutralizing the waste liquid can be suppressed prior to activated sludge treatment, and the waste liquid can be subjected to activated sludge treatment without substantial post-treatment. The present invention was completed based on this knowledge.
即ち、本発明は以下を要旨とする。 That is, the gist of the present invention is as follows.
［１］ 硫化アルカリ類を含有する溶液に、過酸化水素を添加して酸化処理することにより、該硫化アルカリ類を対応する硫酸塩類に変換した後、活性汚泥処理する方法において、
該酸化処理後の溶液中の硫酸塩類の濃度が予め決められた値以上となるように、該硫化アルカリ類を含有する溶液に過酸化水素を存在させた状態で該酸化処理を行うことを含む、硫化アルカリ類含有溶液の処理方法。
[1] A method of converting the alkali sulfide into the corresponding sulfate by adding hydrogen peroxide to a solution containing the alkali sulfide and oxidizing the solution, and then treating the solution with activated sludge,
The oxidation treatment includes performing the oxidation treatment in a state where hydrogen peroxide is present in the solution containing the alkali sulfides so that the concentration of sulfates in the solution after the oxidation treatment is equal to or higher than a predetermined value. , a method for treating a solution containing alkali sulfides.
［２］ 前記硫化アルカリ類を含有する溶液中の硫化アルカリ類濃度に基づいて、前記過酸化水素の添加量を制御する、［１］に記載の硫化アルカリ類含有溶液の処理方法。 [2] The method for treating an alkali sulfide-containing solution according to [1], wherein the amount of hydrogen peroxide added is controlled based on the alkali sulfide concentration in the alkali sulfide-containing solution.
［３］ 前記酸化処理後の前記溶液中の残存過酸化水素の濃度が予め決められた値以下となるように、前記酸化処理の条件を制御することを含む、［１］又は［２］に記載の硫化アルカリ類含有溶液の処理方法。 [3] In [1] or [2], the method includes controlling the conditions of the oxidation treatment so that the concentration of residual hydrogen peroxide in the solution after the oxidation treatment is equal to or less than a predetermined value. The method for treating the alkali sulfide-containing solution described above.
［４］ 前記酸化処理の処理温度が９５℃以下である、［１］～［３］のいずれかに記載の硫化アルカリ類含有溶液の処理方法。 [4] The method for treating an alkali sulfide-containing solution according to any one of [1] to [3], wherein the treatment temperature of the oxidation treatment is 95° C. or lower.
［５］ 前記酸化処理の圧力が３０ｋｇ／ｃｍ２Ｇ以下である、［１］～［４］のいずれかに記載の硫化アルカリ類含有溶液の処理方法。 [5] The method for treating an alkali sulfide-containing solution according to any one of [1] to [4], wherein the pressure of the oxidation treatment is 30 kg/cm 2 G or less.
［６］ 前記硫化アルカリ類が、水硫化アルカリ及び硫化アルカリから選ばれる少なくとも１種を含む、［１］～［５］のいずれかに記載の硫化アルカリ類含有溶液の処理方法。 [6] The method for treating an alkali sulfide-containing solution according to any one of [1] to [5], wherein the alkali sulfide contains at least one selected from alkali hydrosulfides and alkali sulfides.
［７］ 前記水硫化アルカリが水硫化ナトリウムを含む、［６］に記載の硫化アルカリ類含有溶液の処理方法。 [7] The method for treating an alkali sulfide-containing solution according to [6], wherein the alkali hydrosulfide contains sodium hydrosulfide.
［８］ 前記溶液が工程排水である、［１］～［７］のいずれかに記載の硫化アルカリ類含有溶液の処理方法。 [8] The method for treating an alkali sulfide-containing solution according to any one of [1] to [7], wherein the solution is process wastewater.
［９］ 前記溶液を、前記酸化処理に適切なｐＨに調整した後に、ｐＨ調整した前記溶液を前記酸化処理することを含む、［１］～［８］のいずれかに記載の硫化アルカリ類含有溶液の処理方法。 [9] The alkali sulfide-containing method according to any one of [1] to [8], which comprises adjusting the pH of the solution to a pH appropriate for the oxidation treatment, and then subjecting the pH-adjusted solution to the oxidation treatment. How to process the solution.
［１０］ 前記酸化処理後の前記溶液のｐＨを６．０～９．０の範囲内に調整して前記活性汚泥処理することを含む、［１］～［９］のいずれかに記載の硫化アルカリ類含有溶液の処理方法。 [10] The sulfurization according to any one of [1] to [9], comprising adjusting the pH of the solution after the oxidation treatment to within a range of 6.0 to 9.0 and performing the activated sludge treatment. Method for treating alkali-containing solutions.
本発明によれば、水硫化アルカリを含有する溶液を過酸化水素で酸化処理することで、活性汚泥処理可能な処理液を得ることができ、この酸化処理液を、実質的に後処理することなく、活性汚泥処理することが可能となる。 According to the present invention, by oxidizing a solution containing alkali hydrosulfide with hydrogen peroxide, a treated liquid capable of being treated with activated sludge can be obtained, and this oxidized liquid can be substantially post-treated. Activated sludge treatment becomes possible.
以下、本発明を詳細に説明するが、本発明は以下の説明に限定されるものではなく、本発明の要旨を逸脱しない範囲において、任意に変形して実施することができる。 The present invention will be described in detail below, but the present invention is not limited to the following explanation and can be implemented with arbitrary modifications within the scope of the gist of the present invention.
なお、特に断らない限り、本明細書において「～」を用いて表される数値範囲は、「～」の前後に記載された数値を下限値及び上限値として含む範囲を意味し、「Ａ～Ｂ」は、Ａ以上Ｂ以下であることを意味する。 In addition, unless otherwise specified, a numerical range expressed using "~" in this specification means a range that includes the numerical values written before and after "~" as the lower limit value and upper limit value, and "A ~ "B" means greater than or equal to A and less than or equal to B.
また、本明細書において「硫酸塩類」とは、硫化アルカリ類を酸化処理して得られた、該硫化アルカリ類に対応する硫酸塩、亜硫酸塩、及び、チオ硫酸塩のことをいう。前記酸化処理により硫酸塩のみが得られる場合、亜硫酸塩のみが得られる場合、又は、チオ硫酸塩のみが得られる場合、前記「硫酸塩類」とは、それぞれ当該硫酸塩、当該亜硫酸塩、又は当該チオ硫酸塩のことをいう。 Further, in this specification, "sulfates" refer to sulfates, sulfites, and thiosulfates corresponding to the alkali sulfides obtained by oxidizing the alkali sulfides. When only sulfate, only sulfite, or only thiosulfate is obtained by the oxidation treatment, the term "sulfates" refers to the sulfate, sulfite, or thiosulfate, respectively. Refers to thiosulfate.
［硫化アルカリ類含有溶液の処理方法］
本発明の硫化アルカリ類含有溶液の処理方法は、硫化アルカリ類を含有する溶液に、過酸化水素を添加して酸化処理する（以下、適宜「酸化処理工程」という。）ことにより、該硫化アルカリ類を対応する硫酸塩類に変換した後、活性汚泥処理する（以下、適宜「活性汚泥処理工程」という。）方法において、該酸化処理後の溶液中の硫酸塩類の濃度が予め決められた値以上となるように、該硫化アルカリ類を含有する溶液に過酸化水素を存在させた状態で該酸化処理を行うことを含む。
[Method for treating solution containing alkali sulfides]
The method for treating an alkali sulfide-containing solution of the present invention includes adding hydrogen peroxide to a solution containing an alkali sulfide and subjecting it to oxidation treatment (hereinafter referred to as "oxidation treatment step"). In a method in which sulfates are converted into corresponding sulfates and then treated with activated sludge (hereinafter referred to as "activated sludge treatment step"), the concentration of sulfates in the solution after the oxidation treatment is equal to or higher than a predetermined value. The method includes performing the oxidation treatment in a state where hydrogen peroxide is present in a solution containing the alkali sulfide so that the oxidation treatment is performed.
さらに、本発明においては、前記硫化アルカリ類を含有する溶液中の硫化アルカリ類濃度に基づいて、前記過酸化水素の添加量を制御することができる。 Furthermore, in the present invention, the amount of hydrogen peroxide added can be controlled based on the alkali sulfide concentration in the solution containing the alkali sulfides.
さらに、本発明においては、前記酸化処理後の前記溶液中の残存過酸化水素の濃度が予め決められた値以下となるように、前記酸化処理の条件を制御することができる。 Furthermore, in the present invention, the conditions of the oxidation treatment can be controlled so that the concentration of residual hydrogen peroxide in the solution after the oxidation treatment is equal to or less than a predetermined value.
さらに、本発明においては、硫化アルカリ類含有溶液を、酸化処理工程に先立ち、酸化処理に適切なｐＨにｐＨ調整すること（ｐＨ調整工程）ができる。 Furthermore, in the present invention, the pH of the alkali sulfide-containing solution can be adjusted to a pH appropriate for the oxidation treatment (pH adjustment step) prior to the oxidation treatment step.
さらに、本発明においては、酸化処理後は、酸化処理液のｐＨを６．０～９．０の範囲に調整した後に、活性汚泥処理することができる。 Further, in the present invention, after the oxidation treatment, the activated sludge treatment can be performed after adjusting the pH of the oxidation treatment liquid to a range of 6.0 to 9.0.
［硫化アルカリ類含有溶液］
本発明で処理対象とする硫化アルカリ類含有溶液は、硫化アルカリ類を含有する溶液である。
前述のナフサの分解プロセスにおいて、ジメチルジスルフィド（ＤＭＤＳ）等のジスルフィド化合物を含む原料ナフサ、又は、前記ジスルフィド化合物が添加された原料ナフサを熱分解すると、硫化水素（Ｈ２Ｓ）含有ガス及び炭酸ガスを含む分解ガスが生成する。この分解ガスを苛性ソーダ溶液により洗浄する際に、硫化水素（Ｈ２Ｓ）含有ガスと苛性ソーダとが反応することにより水硫化ナトリウム（ＮａＳＨ）や硫化ナトリウム（Ｎａ２Ｓ）等の有害な還元性硫化物塩が発生する。
本発明の処理方法が用いられる使途又は用途は、特に限定されるものではなく、例えば、工程排水、特に、上述した原料ナフサの熱分解により生成した、水硫化ナトリウム（ＮａＳＨ）や硫化ナトリウム（Ｎａ２Ｓ）等の有害な還元性硫化物塩を含む洗浄廃水である、硫化アルカリ類含有溶液の処理に好適に用いることができる。
[Solution containing alkali sulfides]
The alkali sulfide-containing solution to be treated in the present invention is a solution containing alkali sulfides.
In the naphtha decomposition process described above, when raw material naphtha containing a disulfide compound such as dimethyl disulfide (DMDS) or raw material naphtha to which the disulfide compound is added is thermally decomposed, hydrogen sulfide (H 2 S)-containing gas and carbon dioxide gas are generated. Decomposition gas containing When this cracked gas is washed with a caustic soda solution, the hydrogen sulfide (H 2 S)-containing gas reacts with the caustic soda, producing harmful reducing sulfides such as sodium hydrosulfide (NaSH) and sodium sulfide (Na 2 S). Salt is generated.
The uses or uses for which the treatment method of the present invention is used are not particularly limited. It can be suitably used to treat alkali sulfide-containing solutions, which are washing wastewater containing harmful reducing sulfide salts such as 2S ).
このような工程排水等の硫化アルカリ類含有溶液中の水硫化アルカリ、硫化アルカリ等の硫化アルカリ類の濃度は、特に限定されるものではなく、通常は０．１～１０．０質量％程度である。
なお、上記のナフサ分解プロセスの洗浄廃水として排出される硫化アルカリ類含有溶液には、通常、上述した炭酸ガスと苛性ソーダとの反応で発生した炭酸ナトリウム等の炭酸アルカリが１．０～５０．０質量％程度含まれている。このため、後掲の実施例では、この洗浄廃水を模擬して水硫化ナトリウム及び硫化ナトリウムと炭酸ナトリウムを含む試験用水溶液について酸化処理実験を行っている。
The concentration of alkali sulfides such as alkali hydrosulfide and alkali sulfide in a solution containing alkali sulfides such as process wastewater is not particularly limited, and is usually about 0.1 to 10.0% by mass. be.
Note that the alkali sulfide-containing solution discharged as washing waste water from the above-mentioned naphtha decomposition process usually contains 1.0 to 50.0% of alkali carbonate such as sodium carbonate generated by the reaction between carbon dioxide gas and caustic soda. Contains about % by mass. For this reason, in the Examples described below, oxidation treatment experiments were conducted on test aqueous solutions containing sodium bisulfide, sodium sulfide, and sodium carbonate, simulating this washing wastewater.
［酸化処理工程］
本発明における酸化処理工程では、上記のような硫化アルカリ類含有溶液に過酸化水素を添加して硫化アルカリ類含有溶液中の硫化アルカリ類の酸化処理を行う。
当該酸化処理により、硫化アルカリ類含有溶液中の硫化アルカリ類は、該硫化アルカリ類に対応する硫酸塩、該硫化アルカリ類に対応する亜硫酸塩や、該硫酸アルカリ類に対応するチオ硫酸塩に変換される。
[Oxidation treatment process]
In the oxidation treatment step in the present invention, hydrogen peroxide is added to the alkali sulfide-containing solution as described above to oxidize the alkali sulfides in the alkali sulfide-containing solution.
Through the oxidation treatment, the alkali sulfides in the alkali sulfide-containing solution are converted into sulfates corresponding to the alkali sulfides, sulfites corresponding to the alkalis sulfides, and thiosulfates corresponding to the alkalis sulfates. be done.
酸化処理に供する硫化アルカリ類含有溶液の水素イオン濃度指数（ｐＨ）は、特に限定されるものではないが、硫化アルカリ類含有溶液は酸性条件下では悪臭の原因となるＨ２Ｓを発生する虞があることから、ｐＨ７～１４の範囲であることが好ましく、ｐＨ８～１３の範囲であることがより好ましい。
通常、前述のナフサの分解プロセスで排出される洗浄廃水のｐＨは７～１４程度であるが、酸化処理に供する硫化アルカリ類含有溶液のｐＨが上記範囲を外れる場合は、塩酸、硫酸等の酸又は水酸化ナトリウム、水酸化カリウム等のアルカリを添加して、酸化処理に先立ち、予めｐＨを、ｐＨ７～１４の範囲内に調整することが好ましい。
The hydrogen ion concentration index (pH) of the alkali sulfide-containing solution to be subjected to oxidation treatment is not particularly limited, but the alkali sulfide-containing solution may generate H 2 S, which causes a bad odor, under acidic conditions. Therefore, the pH is preferably in the range of 7 to 14, and more preferably in the range of 8 to 13.
Normally, the pH of the washing wastewater discharged from the above-mentioned naphtha decomposition process is about 7 to 14, but if the pH of the alkali sulfide-containing solution used for oxidation treatment is outside the above range, acid such as hydrochloric acid, sulfuric acid, etc. Alternatively, it is preferable to add an alkali such as sodium hydroxide or potassium hydroxide to adjust the pH in advance to within the range of pH 7 to 14 prior to the oxidation treatment.
硫化アルカリ類含有溶液に添加する過酸化水素は、その取扱い性から水溶液の形態で用いることが好ましく、この場合、過酸化水素水溶液の過酸化水素濃度は１０～５０質量％が好ましく、２０～５０質量％であることがより好ましい。過酸化水素濃度が上記下限以上であれば、硫化アルカリ類の酸化処理効率に優れる。一方、過酸化水素濃度が上記上限以下であれば、過酸化水素水溶液の取り扱いが比較的容易となり、安全性の観点から好ましい。 The hydrogen peroxide added to the alkali sulfide-containing solution is preferably used in the form of an aqueous solution from the viewpoint of ease of handling. In this case, the hydrogen peroxide concentration of the aqueous hydrogen peroxide solution is preferably 10 to 50% by mass, and 20 to 50% by mass. It is more preferable that it is mass %. When the hydrogen peroxide concentration is equal to or higher than the above lower limit, the efficiency of oxidation treatment of alkali sulfides is excellent. On the other hand, if the hydrogen peroxide concentration is below the above upper limit, handling of the hydrogen peroxide aqueous solution becomes relatively easy, which is preferable from the viewpoint of safety.
本発明の処理方法においては、酸化処理後の溶液（酸化処理液）中の硫酸塩類の濃度が予め決められた値以上となるように、酸化処理に供する硫化アルカリ類含有溶液に過酸化水素を存在させた状態で該酸化処理を行うことを特徴とする。
この酸化処理液の硫酸塩類の濃度は、酸化処理に供する硫化アルカリ類含有溶液中の硫化アルカリ類の濃度によっても異なるが、硫化アルカリ類含有溶液中の硫化アルカリ類の総質量を１００％として、該硫化アルカリ類の５０質量％以上、特に７０～１００質量％が、該硫化アルカリ類に対応する硫酸塩及び該硫化アルカリ類に対応する亜硫酸塩に酸化処理された濃度であることが、後段の活性汚泥処理における処理効率が優れる観点から好ましい。さらに、前記酸化処理液の硫酸塩類の濃度が、前記硫化アルカリ類のすべて（１００質量％）が該硫化アルカリ類に対応する硫酸塩に酸化処理された濃度であることが、より好ましい。
In the treatment method of the present invention, hydrogen peroxide is added to the alkali sulfide-containing solution to be subjected to the oxidation treatment so that the concentration of sulfates in the solution after the oxidation treatment (oxidation treatment liquid) is a predetermined value or more. It is characterized in that the oxidation treatment is performed in a state in which the oxide is present.
The concentration of sulfates in this oxidation treatment solution varies depending on the concentration of alkali sulfides in the alkali sulfide-containing solution to be subjected to oxidation treatment, but the total mass of alkali sulfides in the alkali sulfide-containing solution is taken as 100%. In the subsequent step, 50% by mass or more, especially 70 to 100% by mass of the alkali sulfides is oxidized to a sulfate corresponding to the alkali sulfide and a sulfite corresponding to the alkali sulfide. It is preferable from the viewpoint of excellent treatment efficiency in activated sludge treatment. Furthermore, it is more preferable that the concentration of sulfates in the oxidation treatment liquid is such that all of the alkali sulfide (100% by mass) is oxidized to the sulfate corresponding to the alkali sulfide.
本発明の処理方法のより好ましい一実施態様として、過酸化水素の添加量を、酸化処理する硫化アルカリ類含有溶液中の硫化アルカリ類の濃度に基づいて制御する方法が挙げられる（実施態様Ａ）。
上述した制御方法として、具体的には、該酸化処理後の溶液中の硫酸塩類の濃度が予め決められた値以上となるように、過酸化水素の添加量を制御することができる。
A more preferred embodiment of the treatment method of the present invention includes a method in which the amount of hydrogen peroxide added is controlled based on the concentration of alkali sulfides in the alkali sulfide-containing solution to be oxidized (Embodiment A). .
Specifically, as the above-mentioned control method, the amount of hydrogen peroxide added can be controlled so that the concentration of sulfates in the solution after the oxidation treatment becomes a predetermined value or more.
或いは、本発明の処理方法のより好ましい、他の実施態様として、前記酸化処理後の酸化処理液中の残存過酸化水素濃度が予め決められた値以下となるように、前記酸化処理の条件を制御する方法が挙げられる（実施態様Ｂ）。
前記酸化処理条件として、具体的には、酸化処理の温度を制御する方法や、過酸化水素の添加量を制御する方法が挙げられる。前述した本発明の処理方法のより好ましい一実施態様である過酸化水素添加量を制御する方法と区別するため、酸化処理の温度を制御する方法がより好ましい。
Alternatively, as another more preferable embodiment of the treatment method of the present invention, the conditions of the oxidation treatment are adjusted so that the residual hydrogen peroxide concentration in the oxidation treatment solution after the oxidation treatment is equal to or less than a predetermined value. (Embodiment B).
Specifically, the oxidation treatment conditions include a method of controlling the temperature of the oxidation treatment and a method of controlling the amount of hydrogen peroxide added. In order to distinguish it from the method of controlling the amount of hydrogen peroxide added, which is a more preferable embodiment of the treatment method of the present invention described above, a method of controlling the temperature of the oxidation treatment is more preferable.
さらに、本発明の処理方法においては、前記実施態様Ａと前記実施態様Ｂとを組み合わせて行うことができる。 Furthermore, in the treatment method of the present invention, embodiment A and embodiment B can be combined.
硫化アルカリ類含有溶液中の硫化アルカリ類の酸化処理に必要な過酸化水素量の量は、
硫化アルカリ類含有溶液中の硫化アルカリ類由来の硫黄原子（Ｓ）の含有量（単位：ｍｏｌ）に対して、４倍モル量である。
即ち、例えば水硫化ナトリウム（ＮａＳＨ）、硫化ナトリウム（Ｎａ２Ｓ）の過酸化水素（Ｈ２Ｏ２）による酸化は以下の反応式に示すように進行するため、硫黄原子（Ｓ）に対して４倍モル量の過酸化水素が反応当量（１当量）となる。
ＮａＳＨ＋４Ｈ２Ｏ２→ＮａＨＳＯ４＋４Ｈ２Ｏ
Ｎａ２Ｓ＋４Ｈ２Ｏ２→Ｎａ２ＳＯ４＋４Ｈ２Ｏ
このため、十分量の過酸化水素の存在下に硫化アルカリ類含有溶液中の硫化アルカリ類を高度に酸化処理して硫酸塩類に変換するには、過酸化水素の添加量は、特に限定されるものではないが、通常は上記反応当量（１当量）を基準として０．５～２．５当量の範囲内にあることが好ましく、０．６～２．０当量の範囲内にあることがより好ましい。
The amount of hydrogen peroxide required for oxidation treatment of alkali sulfides in a solution containing alkali sulfides is:
The molar amount is four times the content (unit: mol) of sulfur atoms (S) derived from alkali sulfides in the alkali sulfide-containing solution.
That is, for example, the oxidation of sodium hydrosulfide (NaSH) and sodium sulfide (Na 2 S) by hydrogen peroxide (H 2 O 2 ) proceeds as shown in the following reaction formula, so that Four times the molar amount of hydrogen peroxide becomes the reaction equivalent (1 equivalent).
NaSH+ 4H2O2 → NaHSO4 + 4H2O
Na2S + 4H2O2 → Na2SO4 + 4H2O
Therefore, in order to highly oxidize the alkali sulfides in the alkali sulfide-containing solution and convert them into sulfates in the presence of a sufficient amount of hydrogen peroxide, the amount of hydrogen peroxide added must be particularly limited. However, it is usually preferably within the range of 0.5 to 2.5 equivalents, more preferably within the range of 0.6 to 2.0 equivalents, based on the above reaction equivalent (1 equivalent). preferable.
一方で、酸化処理液中に酸化処理に使用されなかった余剰の過酸化水素が残留すると、この残存過酸化水素が後段の活性汚泥処理の阻害要因となる。残存過酸化水素による活性汚泥中の微生物の失活を抑制するためには、活性汚泥処理に供される酸化処理液中の残存過酸化水素濃度は１．５質量％以下とすることが好ましく、１．０質量％以下とすることがより好ましい。 On the other hand, if excess hydrogen peroxide that is not used in the oxidation treatment remains in the oxidation treatment liquid, this residual hydrogen peroxide becomes a factor that inhibits the subsequent activated sludge treatment. In order to suppress the deactivation of microorganisms in activated sludge due to residual hydrogen peroxide, the concentration of residual hydrogen peroxide in the oxidation treatment liquid used for activated sludge treatment is preferably 1.5% by mass or less, More preferably, the content is 1.0% by mass or less.
従って、本発明においては、硫化アルカリ類含有溶液中の硫化アルカリ類濃度を予め測定し、過酸化水素の添加量が上記反応当量（１当量）を基準として、好ましくは０．５～２．５当量、より好ましくは０．６～２．０当量となる量とする一方で、酸化処理液中の過酸化水素濃度を測定し、酸化処理液中の残存過酸化水素濃度が上記上限以下となるように、過酸化水素の添加量を制御する。
この過酸化水素の添加量制御は、硫化アルカリ類含有溶液の硫化アルカリ類濃度の測定手段と、酸化処理液の過酸化水素濃度の測定手段と、これらの測定手段の測定値に基づいて過酸化水素の添加量を制御する制御手段とを設けることで、自動制御で実施することができる。
Therefore, in the present invention, the alkali sulfide concentration in the alkali sulfide-containing solution is measured in advance, and the amount of hydrogen peroxide added is preferably 0.5 to 2.5 based on the reaction equivalent (1 equivalent). equivalent, more preferably 0.6 to 2.0 equivalent, while measuring the hydrogen peroxide concentration in the oxidation treatment solution, and ensuring that the residual hydrogen peroxide concentration in the oxidation treatment solution is below the above upper limit. Control the amount of hydrogen peroxide added.
This amount of hydrogen peroxide added is controlled by a means for measuring the alkali sulfide concentration in the alkali sulfide-containing solution, a means for measuring the hydrogen peroxide concentration in the oxidation treatment solution, and a method for controlling the amount of peroxide added based on the measured values of these measuring means. By providing a control means for controlling the amount of hydrogen added, automatic control can be performed.
なお、酸化処理に供される硫化アルカリ類含有溶液中の硫化アルカリ類の含有量は、塩酸等の酸性物質を用いた中和滴定により分析することができる。
また、過酸化水素濃度は、後掲の実施例の項に記載されるように、過マンガン酸カリウムによる酸化還元滴定により分析することができる。
Note that the content of alkali sulfides in the alkali sulfide-containing solution to be subjected to the oxidation treatment can be analyzed by neutralization titration using an acidic substance such as hydrochloric acid.
Further, the hydrogen peroxide concentration can be analyzed by redox titration with potassium permanganate, as described in the Examples section below.
酸化処理の処理温度の上限は、特に限定されるものではないが、通常は９５℃以下であることが好ましい。処理温度が９５℃を超えると反応液が沸騰する虞がある。一方で、酸化処理の処理温度の下限は、特に限定されるものではないが、酸化処理効率の観点から５℃以上であることが好ましい。加熱コストと処理効率等の観点から、酸化処理の処理温度はより好ましくは１０～９０℃である。 Although the upper limit of the treatment temperature for the oxidation treatment is not particularly limited, it is usually preferably 95° C. or lower. If the treatment temperature exceeds 95°C, there is a risk that the reaction liquid will boil. On the other hand, the lower limit of the oxidation treatment temperature is not particularly limited, but is preferably 5° C. or higher from the viewpoint of oxidation treatment efficiency. From the viewpoint of heating cost, processing efficiency, etc., the processing temperature of the oxidation treatment is more preferably 10 to 90°C.
酸化処理の圧力の上限は、特に限定されるものではないが、設備の設計の容易さや設備装置の費用の観点から、３０ｋｇ／ｃｍ２Ｇ以下であることが好ましい。圧力が３０ｋｇ／ｃｍ２Ｇ以下であれば、反応器や配管等の設計が比較的容易となり、設備費用を低く抑えることができる。酸化処理温度にもよるが、過酸化水素による酸化処理は、大気圧（０ｋｇ／ｃｍ２Ｇ）においても円滑に進行するため、加圧コストや耐圧容器等の観点から、酸化処理の圧力は０～２０ｋｇ／ｃｍ２Ｇの範囲とすることが好ましい。 The upper limit of the pressure for the oxidation treatment is not particularly limited, but is preferably 30 kg/cm 2 G or less from the viewpoint of ease of equipment design and cost of equipment. When the pressure is 30 kg/cm 2 G or less, the reactor, piping, etc. can be designed relatively easily, and equipment costs can be kept low. Although it depends on the oxidation treatment temperature, oxidation treatment with hydrogen peroxide proceeds smoothly even at atmospheric pressure (0 kg/cm 2 G), so from the viewpoint of pressurization cost and pressure-resistant container, etc., the pressure of oxidation treatment is 0. The range is preferably 20 kg/cm 2 G.
酸化処理の時間は、特に限定されるものではなく、処理温度及び圧力や過酸化水素添加量等に応じて、硫化アルカリ類含有溶液中の硫化アルカリ類が十分に酸化処理される時間を設定すればよい。 The time for the oxidation treatment is not particularly limited, and the time should be set so that the alkali sulfides in the alkali sulfide-containing solution are sufficiently oxidized, depending on the treatment temperature and pressure, the amount of hydrogen peroxide added, etc. Bye.
本発明における酸化処理では、前述の反応式に示される通り、硫化アルカリ類含有溶液中の硫化アルカリ類、即ち、Ｎａ２Ｓ等の硫化アルカリやＮａＳＨ等の水硫化アルカリが酸化処理されて、チオ硫酸イオン（Ｓ２Ｏ３ ２－）、亜硫酸イオン（ＨＳＯ３ －）、硫酸イオン（ＳＯ４ ２－）のいずれかの、前記硫化アルカリ類に対応するチオ硫酸塩、亜硫酸塩、又は硫酸塩に酸化される。 In the oxidation treatment in the present invention, as shown in the above reaction formula, the alkali sulfides in the alkali sulfide-containing solution, that is, the alkali sulfides such as Na 2 S, and the alkali hydrosulfides such as NaSH, are oxidized to form thiosulfides. To thiosulfate, sulfite, or sulfate corresponding to the alkali sulfide, which is sulfate ion (S 2 O 3 2− ), sulfite ion (HSO 3 − ), or sulfate ion (SO 4 2− ). Oxidized.
前述の通り、本発明においては、酸化処理における過酸化水素添加量、処理温度、処理圧力及び処理時間を適切に設定することで、硫化アルカリ類の５０質量％以上、特に７０～１００質量％が、該硫化アルカリ類に対応する硫酸塩及び該硫化アルカリ類に対応する亜硫酸塩に酸化処理されること、特にすべて（１００質量％）の硫化アルカリ類が前記硫酸塩に酸化処理されることが、後段の活性汚泥処理効率の観点から好ましい。 As mentioned above, in the present invention, by appropriately setting the amount of hydrogen peroxide added, treatment temperature, treatment pressure, and treatment time in the oxidation treatment, 50% by mass or more, especially 70 to 100% by mass of alkali sulfides can be , being oxidized to a sulfate corresponding to the alkali sulfide and a sulfite corresponding to the alkali sulfide, in particular, oxidizing all (100% by mass) of the alkali sulfide to the sulfate; This is preferable from the viewpoint of the efficiency of activated sludge treatment in the latter stage.
［活性汚泥処理工程］
酸化処理工程で得られる酸化処理液は、活性汚泥処理に供される。本発明では、酸化処理液中の残存過酸化水素濃度が低く抑えることができるため、酸化処理後の活性汚泥処理における過酸化水素による活性阻害の問題は殆どない。
活性汚泥処理は、以下の通り、常法に従って行うことができる。
[Activated sludge treatment process]
The oxidation treatment liquid obtained in the oxidation treatment step is subjected to activated sludge treatment. In the present invention, since the concentration of residual hydrogen peroxide in the oxidation treatment liquid can be kept low, there is almost no problem of activity inhibition due to hydrogen peroxide in activated sludge treatment after oxidation treatment.
Activated sludge treatment can be performed according to a conventional method as follows.
活性汚泥処理による排水処理装置は、原水槽、薬液を排水に注入して前処理を行い、かつ排水を温度調整する中和槽、排水を酸素曝気しつつ排水中の有機物を酸化分解、凝集させる曝気槽、及び凝集汚泥を沈澱させる沈澱槽を備え、活性汚泥法により排水を浄化し、浄化した濁度の低い処理水を流出させる。
活性汚泥法による排水処理方法は、排水の生物処理法の一つであって、排水中の各種の有機物を培養基として、溶存酸素の存在下で微生物の混合集団を連続培養し、酸化分解、凝集、沈澱の各作用により主として排水中の有機物を除去する処理方法である。技報堂
出版の「水処理工学」によれば、活性汚泥処理プロセス は、浄化機能を有するフロック状の生物増殖体を必要に応じて生物反応系で絶えず循環し、曝気槽内で基質（排水のＢＯＤ成分）と浄化微生物の比率が一定となるように人為的に操作し、溶存酸素の存在のもとで、異種個体
群の微生物によって構成されるフロックと基質とを十分に接触せしめて、これを好気的に酸化、分解する処理プロセスであると定義されている。
Wastewater treatment equipment using activated sludge treatment consists of a raw water tank, a neutralization tank that pre-treats the wastewater by injecting chemicals into the wastewater and adjusts the temperature of the wastewater, and aerates the wastewater with oxygen to oxidize, decompose, and coagulate organic matter in the wastewater. Equipped with an aeration tank and a settling tank to settle flocculated sludge, wastewater is purified using the activated sludge method, and the purified treated water with low turbidity is discharged.
The activated sludge method is a biological treatment method for wastewater, in which a mixed population of microorganisms is continuously cultured in the presence of dissolved oxygen using various organic substances in wastewater as a culture medium, resulting in oxidative decomposition and flocculation. This is a treatment method that mainly removes organic matter from wastewater through the effects of precipitation. According to ``Water Treatment Engineering'' published by Gihodo Publishing, the activated sludge treatment process involves constantly circulating floc-like biological growth bodies with a purification function in a biological reaction system as needed, and removing the substrate (BOD of wastewater) in an aeration tank. In the presence of dissolved oxygen, flocs composed of heterogeneous populations of microorganisms are brought into sufficient contact with the substrate, and the It is defined as a treatment process that involves aerobic oxidation and decomposition.
このような活性汚泥処理は、微生物の活性及び安定した活性汚泥処理の観点から、ｐＨ６．０～９．０の中性域で行うことが好ましい。
このため、活性汚泥処理に供する酸化処理液のｐＨは、ｐＨ６．０～９．０に調整することが好ましく、ｐＨ６．５～９．０に調整することがより好ましい。
Such activated sludge treatment is preferably carried out in a neutral pH range of 6.0 to 9.0 from the viewpoint of microbial activity and stable activated sludge treatment.
Therefore, the pH of the oxidation treatment liquid used for activated sludge treatment is preferably adjusted to pH 6.0 to 9.0, more preferably adjusted to pH 6.5 to 9.0.
通常、前述の酸化処理を行って得られる酸化処理液のｐＨは、硫酸塩の生成でｐＨ８～１３程度となることがある。このような場合、硫酸等の酸性物質を添加して、酸化処理液のｐＨを上記ｐＨの範囲内に調整することができる。
本発明によれば、酸化処理液にｐＨ調整を行うのみで、その他の処理を施すことなく活性汚泥処理に供することができる。
Normally, the pH of the oxidation treatment solution obtained by performing the above-mentioned oxidation treatment may be about pH 8 to 13 due to the formation of sulfate. In such a case, the pH of the oxidation treatment solution can be adjusted within the above pH range by adding an acidic substance such as sulfuric acid.
According to the present invention, the oxidation treatment liquid can be subjected to activated sludge treatment only by adjusting the pH thereof and without performing any other treatment.
活性汚泥処理を行って得られる活性汚泥処理液は、ＣＯＤＭｎが十分に低減されており、そのまま、或いは必要に応じて濾過等の処理を行った後、放流される。 The activated sludge treatment liquid obtained by performing activated sludge treatment has COD Mn sufficiently reduced, and is discharged as it is or after performing treatment such as filtration as necessary.
［ナフサ分解プロセスへの適用］
本発明で処理対象とする硫化アルカリ類含有溶液の一例として、ナフサ分解プロセスからの洗浄廃水を酸化処理する場合の処理工程について、説明する。
[Application to naphtha cracking process]
As an example of the alkali sulfide-containing solution to be treated in the present invention, a treatment process for oxidizing cleaning wastewater from a naphtha decomposition process will be described.
原料ナフサに、ジメチルジスルフィド（ＤＭＤＳ）が添加された後、分解炉に送給されて熱分解される。分解炉からの熱分解生成物は、軽沸成分と重沸成分に分離され、エチレン、プロピレン等は分留工程へ送給される。熱分解中にＤＭＳから生成した硫化水素（Ｈ２Ｓ）を含む分解ガスは、ソーダ洗浄塔に送給され、苛性ソーダ（ＮａＯＨ）溶液により洗浄される。 After dimethyl disulfide (DMDS) is added to raw material naphtha, it is sent to a cracking furnace and thermally cracked. The thermal decomposition products from the cracking furnace are separated into light boiling components and heavy boiling components, and ethylene, propylene, etc. are sent to a fractionation process. The cracked gas containing hydrogen sulfide (H 2 S) generated from DMS during pyrolysis is sent to a soda washing tower and washed with a caustic soda (NaOH) solution.
ソーダ洗浄塔において、硫化水素と苛性ソーダが反応して水硫化ソーダ及び硫化ソーダが生成する。また、分解ガスが炭酸ガス（二酸化炭素）を含む場合は、炭酸ガスと苛性ソーダが反応して炭酸ソーダが生成する。このようにして生成した水硫化ソーダ（水硫化ナトリウム）等や炭酸ソーダを含む洗浄廃水は、必要に応じてｐＨ調整された後、本発明による酸化処理の処理対象の硫化アルカリ類含有溶液として、ポンプＰにより過酸化水素が添加され酸化処理に供される。そして、酸化処理液は、好ましくはｐＨ５～１４の範囲内、より好ましくはｐＨ６．０～９．０の範囲内にｐＨ調整された後、活性汚泥処理に供され、活性汚泥処理液は、必要に応じて後処理された後、河川ないし海に放流される。 In the soda washing tower, hydrogen sulfide and caustic soda react to produce sodium bisulfide and sodium sulfide. Further, when the cracked gas contains carbon dioxide gas (carbon dioxide), carbon dioxide gas and caustic soda react to generate carbonate soda. The cleaning wastewater containing sodium bisulfide (sodium bisulfide) and sodium carbonate thus generated is pH-adjusted as necessary, and then treated as an alkali sulfide-containing solution to be subjected to the oxidation treatment according to the present invention. Hydrogen peroxide is added by pump P and subjected to oxidation treatment. Then, the oxidation treatment liquid is subjected to activated sludge treatment after being pH adjusted to preferably within the range of pH 5 to 14, more preferably within the range of pH 6.0 to 9.0, and the activated sludge treatment liquid is After being processed according to the requirements, they are discharged into rivers or the sea.
本実施形態では、炭酸ソーダ廃水中の硫化アルカリ類濃度（又は硫黄濃度）を測定する測定手段、酸化処理液中の過酸化水素濃度を測定する測定手段と、これらの測定手段の測定値が入力される制御装置が設けられており、該制御装置は、入力された炭酸ソーダ廃水の硫化アルカリ類濃度（又は硫黄濃度）の測定値と、酸化処理液の過酸化水素濃度の測定値とから、前述の処理すべき硫化アルカリ類に対する過酸化水素の好適当量及び酸化処理液の残存過酸化水素濃度となるように、必要な過酸化水素添加量を演算し、算出した過酸化水素添加量となるように、過酸化水素添加用ポンプの制御信号を出力する。
このような過酸化水素添加量の制御を行うことで、硫化アルカリ類含有溶液中の硫化アルカリ類を高度に酸化処理して硫酸塩類に変換すると共に、酸化処理液中の過酸化水素濃度を、後段の活性汚泥処理に影響を及ぼすことのない濃度として、酸化処理及び活性汚泥処理を効率的に行うことができる。
In this embodiment, a measuring means for measuring the alkali sulfide concentration (or sulfur concentration) in the sodium carbonate wastewater, a measuring means for measuring the hydrogen peroxide concentration in the oxidation treatment liquid, and the measured values of these measuring means are input. A control device is provided, and the control device calculates, from the input measured value of the alkali sulfide concentration (or sulfur concentration) of the sodium carbonate wastewater and the measured value of the hydrogen peroxide concentration of the oxidation treatment liquid. The necessary amount of hydrogen peroxide to be added is calculated so that the appropriate amount of hydrogen peroxide for the alkali sulfides to be treated and the residual hydrogen peroxide concentration in the oxidation treatment solution are obtained, and the calculated amount of hydrogen peroxide and The control signal for the hydrogen peroxide addition pump is output so that the amount of hydrogen peroxide is increased.
By controlling the amount of hydrogen peroxide added in this manner, the alkali sulfides in the alkali sulfide-containing solution are highly oxidized and converted into sulfates, and the hydrogen peroxide concentration in the oxidized solution is reduced. Oxidation treatment and activated sludge treatment can be performed efficiently at a concentration that does not affect the subsequent activated sludge treatment.
以下に実施例を挙げて、本発明をより具体的に説明するが、本発明はこれらの実施例により限定されるものではない。 The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples.
以下の実施例で使用した化合物の名称は以下のとおりである。
水硫化ナトリウム（商品名：ＮａＳＨ・ｎＨ２Ｏ、富士フイルム和光純薬（株）製）
硫化ナトリウム（商品名：Ｎａ２Ｓ・５Ｈ２Ｏ、富士フイルム和光純薬（株）製）
炭酸ナトリウム（商品名：ＮａＣＯ３、富士フイルム和光純薬（株）製）
４５質量％過酸化水素水（三菱ガス化学（株）製）
水（商品名：精製水 Ｐｕｒｅ Ｗａｔｅｒ、富士フイルム和光純薬（株）製）
The names of the compounds used in the following examples are as follows.
Sodium hydrosulfide (product name: NaSH・nH 2 O, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
Sodium sulfide (product name: Na 2 S.5H 2 O, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
Sodium carbonate (product name: NaCO 3 , manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
45% by mass hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Co., Ltd.)
Water (Product name: Pure Water, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
＜評価方法＞
（１）水硫化アルカリ、硫化アルカリ及び炭酸アルカリ水溶液の調製方法
水硫化アルカリとして水硫化ナトリウム、硫化アルカリとして硫化ナトリウム、炭酸アルカリとして炭酸ナトリウム、及び水を下記に示した質量比率で配合して、ｐＨ１２．２の試験用水溶液を調製した。
（試験用水溶液の組成）
・水硫化ナトリウム： ０．３質量％
・硫化ナトリウム ： ０．１質量％
・炭酸ナトリウム ：２０．０質量％
・水 ：７９．６質量％
<Evaluation method>
(1) Method for preparing aqueous solutions of alkali hydrosulfide, alkali sulfide, and alkali carbonate Blend sodium hydrosulfide as the alkali hydrosulfide, sodium sulfide as the alkali sulfide, sodium carbonate as the alkali carbonate, and water in the mass ratio shown below. A test aqueous solution with a pH of 12.2 was prepared.
(Composition of test aqueous solution)
・Sodium hydrosulfide: 0.3% by mass
・Sodium sulfide: 0.1% by mass
・Sodium carbonate: 20.0% by mass
・Water: 79.6% by mass
（２）酸化処理方法
（１）で調製した試験用水溶液１００ｇに対して、４５質量％過酸化水素水を、前記試験用水溶液に含まれる硫黄原子（Ｓ）の含有量（単位：ｍｏｌ）に対して、過酸化水素として４倍モル量を１当量として、所定の当量となるように添加し、温度４０℃、大気圧下（圧力０ｋｇ／ｃｍ２Ｇ）で酸化処理した。
(2) Oxidation treatment method To 100 g of the test aqueous solution prepared in (1), add 45% by mass hydrogen peroxide solution to the content (unit: mol) of sulfur atoms (S) contained in the test aqueous solution. On the other hand, 1 equivalent of 4 times the molar amount of hydrogen peroxide was added to give a predetermined equivalent, and oxidation treatment was performed at a temperature of 40°C and atmospheric pressure (pressure of 0 kg/cm 2 G).
（３）残存過酸化水素の濃度測定
酸化処理後の試験用水溶液に１．０Ｍ硫酸水溶液をｐＨ２～７の範囲内となるように添加した。次いで、ビュレットを使用して０．０２Ｍ過マンガン酸カリウム溶液による酸化還元滴定を行い、酸化処理後の試験用水溶液中の過酸化水素の濃度（単位：質量％）を測定した。
(3) Measurement of concentration of residual hydrogen peroxide A 1.0 M sulfuric acid aqueous solution was added to the test aqueous solution after the oxidation treatment so that the pH was within the range of 2 to 7. Next, redox titration was performed using a 0.02M potassium permanganate solution using a buret, and the concentration of hydrogen peroxide (unit: mass %) in the test aqueous solution after the oxidation treatment was measured.
（４）硫酸塩類の含有量測定
酸化処理後の試験用溶液中に含まれる、硫酸塩類の含有量として、チオ硫酸イオン、亜硫酸イオン及び硫酸イオンの含有量を、下記の方法に従って測定した。
試験用溶液中の水硫化ナトリウム及び硫化ナトリウムが酸化処理されることにより、硫酸塩として、チオ硫酸イオン、亜硫酸イオン及び硫酸イオンが生成するので、本測定では、これらのイオンの含有量を測定する。
具体的には、前記（２）で得られた酸化処理後の試験用水溶液について、イオンクロマトグラフィーを用いて、チオ硫酸イオン、亜硫酸イオン及び硫酸イオンのそれぞれの含有量Ｃ２－１、Ｃ２－２、Ｃ２－３（単位：ｍｏｌ）を測定した。
(4) Measurement of sulfate content As the sulfate content contained in the test solution after oxidation treatment, the content of thiosulfate ion, sulfite ion, and sulfate ion was measured according to the following method.
When sodium bisulfide and sodium sulfide in the test solution are oxidized, thiosulfate ions, sulfite ions, and sulfate ions are generated as sulfates, so in this measurement, the content of these ions is measured. .
Specifically, for the test aqueous solution obtained in (2) after the oxidation treatment, the respective contents of thiosulfate ion, sulfite ion, and sulfate ion, C 2-1 and C 2 , were determined using ion chromatography. -2 and C 2-3 (unit: mol) were measured.
（５）硫酸塩類及び硫化アルカリ類の含有割合の算出
前記（１）で調製した酸化処理前の試験用水溶液について、水硫化ナトリウムと硫化ナトリウムの仕込み量から、水硫化ナトリウム及び硫化ナトリウムの合計含有量Ｃ１（単位：ｍｏｌ）を算出した。
酸化処理前の試験用水溶液中のＣ１から、前記（４）で算出した酸化処理後の試験用水溶液中のチオ硫酸イオン、亜硫酸イオン及び硫酸イオンの含有量Ｃ２－１、Ｃ２－２、Ｃ２－３を引いて、これを酸化処理後の試験用水溶液中の硫化アルカリ類の含有量Ｃ２－４（単位：ｍｏｌ）とした。
得られたＣ２－１～Ｃ２－４の値から、酸化処理後の試験用溶液中に含まれる、硫酸塩類及び硫化アルカリ類の含有割合として、チオ硫酸イオン、亜硫酸イオン、硫酸イオン、並びに、水硫化ナトリウム及び硫化ナトリウム（合計）の合計含有量（単位：ｍｏｌ）を１００％としたときの、チオ硫酸イオン、亜硫酸イオン、硫酸イオン、並びに、水硫化ナトリウム及び硫化ナトリウム（合計）の、それぞれの含有割合（単位：ｍｏｌ％）を算出した。
(5) Calculation of the content ratio of sulfates and alkali sulfides Regarding the test aqueous solution before oxidation treatment prepared in (1) above, the total content of sodium bisulfide and sodium sulfide is determined from the amount of sodium bisulfide and sodium sulfide charged. The amount C 1 (unit: mol) was calculated.
Contents of thiosulfate ion, sulfite ion, and sulfate ion in the test aqueous solution after oxidation treatment calculated in (4) from C 1 in the test aqueous solution before oxidation treatment C 2-1 , C 2-2 , C 2-3 was subtracted, and this was determined as the content of alkali sulfides C 2-4 (unit: mol) in the test aqueous solution after the oxidation treatment.
From the obtained values of C 2-1 to C 2-4 , the content ratio of sulfates and alkali sulfides contained in the test solution after oxidation treatment is determined as thiosulfate ion, sulfite ion, sulfate ion, and , thiosulfate ion, sulfite ion, sulfate ion, and sodium hydrosulfide and sodium sulfide (total), when the total content (unit: mol) of sodium hydrosulfide and sodium sulfide (total) is 100%. The content ratio (unit: mol%) of each was calculated.
［実施例１］
上述した調製方法（１）で調製した試験用水溶液１００ｇに、上述した前記（２）の手順に従って、過酸化水素を１．２当量添加し、酸化処理を行った。過酸化水素を添加して酸化処理を開始してから１５分後に酸化処理を停止した。
酸化処理後の試験用溶液について、上述した前記（３）の手順に従って残存過酸化水素の濃度を測定した。
また、酸化処理後の試験用溶液について、上述した前記（４）及び前記（５）の手順に従って、硫酸塩類及び硫化アルカリ類の含有量（単位：ｍｏｌ）及び含有割合（単位：ｍｏｌ％）を測定した。評価結果を表１に示した。
[Example 1]
1.2 equivalents of hydrogen peroxide was added to 100 g of the test aqueous solution prepared by the above-mentioned preparation method (1) according to the above-mentioned procedure (2), and oxidation treatment was performed. The oxidation treatment was stopped 15 minutes after adding hydrogen peroxide and starting the oxidation treatment.
Regarding the test solution after the oxidation treatment, the concentration of residual hydrogen peroxide was measured according to the procedure (3) above.
In addition, for the test solution after oxidation treatment, the content (unit: mol) and content ratio (unit: mol%) of sulfates and alkali sulfides were determined according to the above-mentioned procedures (4) and (5). It was measured. The evaluation results are shown in Table 1.
実施例１で得られた酸化処理後の試験用溶液を、活性汚泥処理に供したところ、ＣＯＤＭｎ１１０ｍｇ／Ｌの活性汚泥処理液を得ることができた。なお、酸化処理前のＣＯＤＭｎの値は２，０００ｍｇ／Ｌであった。 When the test solution obtained in Example 1 after the oxidation treatment was subjected to activated sludge treatment, an activated sludge treatment liquid having a COD Mn of 110 mg/L could be obtained. Note that the COD Mn value before oxidation treatment was 2,000 mg/L.
［比較例１］
実施例１における過酸化水素の添加量を０．２当量に変更した以外は、実施例１と同様の条件で酸化処理を行ない、残存過酸化水素の濃度、硫酸塩類及び硫化アルカリ類の含有量及び含有割合を測定した。評価結果を表１に示した。
[Comparative example 1]
The oxidation treatment was carried out under the same conditions as in Example 1, except that the amount of hydrogen peroxide added in Example 1 was changed to 0.2 equivalent, and the concentration of residual hydrogen peroxide, the content of sulfates and alkali sulfides were and the content ratio was measured. The evaluation results are shown in Table 1.
［実施例２］
実施例１における過酸化水素の添加量を１．５当量に変更した以外は、実施例１と同様の条件で酸化処理を行ない、残存過酸化水素の濃度、硫酸塩類及び硫化アルカリ類の含有量及び含有割合を測定した。評価結果を表１に示した。
得られた酸化処理後の試験用溶液を実施例１と同様に活性汚泥処理したところ、得られた活性汚泥処理液のＣＯＤＭｎは７０ｍｇ／Ｌであった。なお、酸化処理前のＣＯＤＭｎの値は２，０００ｍｇ／Ｌであった。
[Example 2]
The oxidation treatment was carried out under the same conditions as in Example 1, except that the amount of hydrogen peroxide added in Example 1 was changed to 1.5 equivalents, and the concentration of residual hydrogen peroxide, the content of sulfates and alkali sulfides were and the content ratio was measured. The evaluation results are shown in Table 1.
When the obtained test solution after the oxidation treatment was treated with activated sludge in the same manner as in Example 1, the COD Mn of the obtained activated sludge treated liquid was 70 mg/L. Note that the COD Mn value before oxidation treatment was 2,000 mg/L.
［比較例２］
実施例１における過酸化水素の添加量を３．０当量に変更した以外は、実施例１と同様の条件で酸化処理を行ない、残存過酸化水素の濃度、硫酸塩類及び硫化アルカリ類の含有量及び含有割合を測定した。評価結果を表１に示した。
[Comparative example 2]
The oxidation treatment was carried out under the same conditions as in Example 1, except that the amount of hydrogen peroxide added in Example 1 was changed to 3.0 equivalents, and the concentration of residual hydrogen peroxide, the content of sulfates and alkali sulfides were and the content ratio was measured. The evaluation results are shown in Table 1.
実施例１、２及び比較例２の製造条件では、酸化処理前の試験用水溶液中の硫化アルカリ類（水硫化ナトリウム及び硫化ナトリウム）は、過酸化水素を添加して酸化処理することにより、硫化アルカリ類の全量が硫酸塩類（硫酸イオン）に転化された。
特に、実施例１及び２の酸化処理条件では、硫化アルカリ類（水硫化ナトリウム及び硫化ナトリウム）から硫酸塩類への転化率は１００％であり、かつ酸化処理後の試験用水溶液中に残存する過酸化水素の濃度は、定量下限未満（０．５質量％未満）であった。
このため、実施例１、２ではＣＯＤＭｎが十分に低減された活性汚泥処理液が得られた。
一方、比較例１の酸化処理条件では、過酸化水素の添加量が少ないため（０．２当量）、硫化アルカリ類（水硫化ナトリウム及び硫化ナトリウム）から硫酸塩類への転化率は３６．４ｍｏｌ％（１８．２＋１２．１＋６．１＝３６．４）であった。
また、比較例２の酸化処理条件では、過酸化水素の添加量が多いため（３．０当量）、硫化アルカリ類（水硫化ナトリウム及び硫化ナトリウム）から硫酸塩類への転化率は１００％であったが、酸化処理後の試験用水溶液中に残存する過酸化水素の濃度は１．６質量％であった。
この比較例２では、試験用水溶液の過酸化水素濃度が高いため、活性汚泥処理における微生物阻害の問題が懸念される。
Under the manufacturing conditions of Examples 1 and 2 and Comparative Example 2, the alkali sulfides (sodium hydrosulfide and sodium sulfide) in the test aqueous solution before oxidation treatment were oxidized by adding hydrogen peroxide. The entire amount of alkalis was converted to sulfates (sulfate ions).
In particular, under the oxidation treatment conditions of Examples 1 and 2, the conversion rate from alkali sulfides (sodium bisulfide and sodium sulfide) to sulfates was 100%, and the excess remaining in the test aqueous solution after oxidation treatment was 100%. The concentration of hydrogen oxide was below the lower limit of quantification (less than 0.5% by mass).
Therefore, in Examples 1 and 2, activated sludge treatment liquids with sufficiently reduced COD Mn were obtained.
On the other hand, under the oxidation treatment conditions of Comparative Example 1, since the amount of hydrogen peroxide added was small (0.2 equivalent), the conversion rate from alkali sulfides (sodium hydrosulfide and sodium sulfide) to sulfates was 36.4 mol%. (18.2+12.1+6.1=36.4).
Furthermore, under the oxidation treatment conditions of Comparative Example 2, since the amount of hydrogen peroxide added was large (3.0 equivalents), the conversion rate from alkali sulfides (sodium hydrosulfide and sodium sulfide) to sulfates was 100%. However, the concentration of hydrogen peroxide remaining in the test aqueous solution after the oxidation treatment was 1.6% by mass.
In Comparative Example 2, since the hydrogen peroxide concentration in the test aqueous solution is high, there is concern about the problem of microbial inhibition in activated sludge treatment.
以上の実施例及び比較例より、酸化処理後の硫酸塩類の濃度が所定値以上となるように、好ましくは、硫化アルカリ類含有溶液中の硫化アルカリ類（又は硫黄）濃度、更には酸化処理液の過酸化水素濃度に基づいて過酸化水素添加量を制御する本発明の硫化アルカリ類含有溶液の処理方法よれば、硫化アルカリ類（水硫化ナトリウム及び硫化ナトリウム）等の有害な還元性硫化物塩を含む、洗浄廃水等の硫化アルカリ類含有溶液を、過酸化水素水で効率的に酸化処理して、無害な硫酸塩類に分解することができると共に、活性汚泥処理の阻害要因となる過酸化水素の残留を抑制して酸化処理液を効率的に活性汚泥処理に供することができることが期待される。
また、廃液を活性汚泥処理する前の還元性硫化物塩の中和処理が不要となるため、悪臭の原因となるＨ２Ｓが発生することを回避できることが期待される。
特に、本発明の硫化アルカリ類含有溶液の処理方法によれば、酸化処理液を、過酸化水素を含まない、又は、過酸化水素濃度の低い酸化処理液とすることができるため、活性汚泥処理に供しても、活性汚泥中の微生物を失活させることがないことが期待される。
From the above Examples and Comparative Examples, it is preferable to adjust the concentration of alkali sulfides (or sulfur) in the alkali sulfide-containing solution, and further to the oxidation treatment solution so that the concentration of sulfates after oxidation treatment is equal to or higher than a predetermined value. According to the method for treating an alkali sulfide-containing solution of the present invention, which controls the amount of hydrogen peroxide added based on the hydrogen peroxide concentration of It is possible to efficiently oxidize alkali sulfide-containing solutions such as washing wastewater, including hydrogen peroxide, to decompose them into harmless sulfates, and also to remove hydrogen peroxide, which is an inhibiting factor in activated sludge treatment. It is expected that the oxidation treatment liquid can be efficiently used for activated sludge treatment by suppressing the residual amount of .
Furthermore, since neutralization treatment of reducing sulfide salts before treating the waste liquid with activated sludge becomes unnecessary, it is expected that generation of H 2 S, which causes bad odor, can be avoided.
In particular, according to the method for treating an alkali sulfide-containing solution of the present invention, the oxidation treatment liquid can be an oxidation treatment liquid that does not contain hydrogen peroxide or has a low concentration of hydrogen peroxide. It is expected that the microorganisms in activated sludge will not be deactivated even if subjected to water.
Claims (10)
該酸化処理後の溶液中の硫酸塩類の濃度が予め決められた値以上となるように、該硫化アルカリ類を含有する溶液に過酸化水素を存在させた状態で該酸化処理を行うことを含む、硫化アルカリ類含有溶液の処理方法。 In a method of converting the alkali sulfide into the corresponding sulfate by adding hydrogen peroxide to a solution containing the alkali sulfide and oxidizing the solution, and then treating the alkali sulfide with activated sludge,
The oxidation treatment includes performing the oxidation treatment in a state where hydrogen peroxide is present in the solution containing the alkali sulfides so that the concentration of sulfates in the solution after the oxidation treatment is equal to or higher than a predetermined value. , a method for treating a solution containing alkali sulfides.
The alkali sulfide-containing solution according to any one of claims 1 to 9, comprising adjusting the pH of the solution after the oxidation treatment to within a range of 6.0 to 9.0 and performing the activated sludge treatment. How to process the solution.
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