2005 Fiscal Year Final Research Report Summary
A Study on Behaviors of Active Oxygen Species during Ozonation and Ozone/hydrogen peroxide Process of Wastewater
| Project/Area Number |
16560479
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Civil and environmental engineering
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
YAMADA Harumi KYOTO UNIVERSITY, Graduate School of Eng., Associate professor, 工学研究科, 助教授 (40089123)
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| Co-Investigator(Kenkyū-buntansha) |
TSUNO Hiroshi KYOTO UNIVERSITY, Graduate School of Eng., Professor, 工学研究科, 教授 (40026315)
HIDAKA Taira KYOTO UNIVERSITY, Graduate School of Eng., Assistant Professor, 工学研究科, 助手 (30346093)
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| Project Period (FY) |
2004 – 2005
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| Keywords | ozone / hydrogen peroxide / hydroxyl radical / bromate ion |
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| Research Abstract |
During treatment of water containing Br^- by ozone-based processes, ozone can oxidize Br^- to HOBr or OBr^-. HOBr/OBr^- could be oxidized to BrO_3^- by O_3 and/or HO・. There is another pathway in BrO_3^- formation through HO・ and then ozone, which is commonly referred to as the indirect-direct pathway. The O_3/H_2O_2 process has also possibility to lead to an increase in the formation of BrO_3^- through HO・ and O_3. Though the addition of H_2O_2 in water treatment has been shown to result in a decrease in brominated organic compounds, the fate of BrO_3^- is still un clear.
In this study, effluent from conventional activated sludge process in municipal wastewater treatment plant was treated with ozone alone and with O_3/H_2O_2 in semi batch mode. From the relationship between the amounts of bromate ion formed and dissolved ozone concentration, bromate ion concentration started to increase after dissolved ozone concentration reached 0.1 mg/L. After the appearance of dissolved ozone, bromate ion was formed with high speed. It is considered that the critical factor for bromate ion formation is the dissolved ozone concentration in O_3/H_2O_2 treatment. Therefore, when the injection amount of H_2O_2 exceeded 0.5 H_2O_2 added/O_3 consumed (mole/mole), bromate ion formation could be controlled.
In the cases of injected H_2O_2/O_3 mole ratio of above 0.5 (mole/mole), dissolved ozone concentration was below 0.1 mg/L, and bromate ion did not form. However, when injected the H_2O_2/O_3 mole ratio was below 0.5 (mole/mole), bromate ion was increased. TOBr is useful as a parameter on estimating the formation of brominated organic compounds and individual brominated organic compounds including DBAA, bromoform were also not increased during O_3/H_2O_2 treatment.
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Research Products
(2 results)
