1997 Fiscal Year Final Research Report Summary
Characterization and minimization of health risks by desinfection and oxidation by-products in drinking water treatment process
| Project/Area Number |
07405025
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 | National Institute of Public Health |
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Principal Investigator |
AIZAWA Takako National Institute of public Health, Department of Water Supply Engineering, Chief, 水道工学部, 室長 (10192832)
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| Co-Investigator(Kenkyū-buntansha) |
ASAMI Mari National Institute of Public Health, Department of Water Supply Engineering, Res, 水道工学部, 研究員 (90260265)
MAGARA Yasumoto Hokkaido University, Faculty of Engineering, Professor, 大学院・工学研究科, 教授 (60083739)
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| Project Period (FY) |
1995 – 1997
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| Keywords | drinkingwater / disinfection by-product / bromate / quantitative structure activity relationsip / toxicity estimation / health risk |
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| Research Abstract |
Water oxidation is one of necessary unit process in drinking water treatment, especially for disinfection or pretreatment of micropollutants. Chlorination and ozonation are most popular oxidation processes in conventional and advanced treatment process. Besides chlorination yields chlorination by-products such as trihalomethane, ozonation yields bromate, bromide-containing oxidation by-product, which is a strong carcinogen.
Analytical conditions of bromate using ionchromatography along with pretreatment of silver cartridge and borate elluent was established in our study. The quantitative detection limit was 2 mug/l. Bromate was found in several drinking water treatment processes in japan.
Formation of bromate depends on bromide concentration in raw water, ozonation conditions and co-existing constituents. In laboratory-scale ozonation experiments of natural river water, bromate formation was inhibited by coexisting organic matters in original water, while total organic halides (TOX) and
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aldehydes were increased. Phosphate also worked as a scavenger to inhibit bromate formation in ozonation.
Bromate concentration in an experimental ozonation plant was observed. Bromate concentration was correlated with ozone dose and temperature. Since elimination of bromate with following GAC/BAC process was difficult, control of bromate formation in ozonation is necessary.
Health risk of bromate was estimated relatively high compared to other organic by-products formed in oxidation. In some cases, life time cancer risk of bromate elevated to 10^<-4> level. Toxicity of other organic oxidation by-products were estimated using QSAR,quantitative structure activity relationship. Bromide substituents with chlorination by-products showed stronger potential of toxicity. Out of 29 mouse and rat carcinogenicity estimation data for halogenated organic substances, 86% (25 cases) were matched with experimental results. Risk estimation and minimization can be applied for selecting alternative disinfectants. Less
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