Biomedical analyses of roof-harvested rainwater in household storage tanks for efficient use of water resources in Azumino area

Research Project

Project/Area Number	24651024
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Environmental impact assessment/Environmental policy
Research Institution	Shinshu University
Principal Investigator	OANA Kozue 信州大学, 学術研究院保健学系, 助教 (60115334)
Co-Investigator(Kenkyū-buntansha)	KAWAKAMI Yoshiyuki 信州大学, 医学部, 特任教授 (90283275)
Research Collaborator	KOBAYASHI Michiko 信州大学, 大学院医学系研究科保健学専攻 YAMAKI Dai 株式会社信州セラミックス, 研究員
Project Period (FY)	2012-04-01 – 2015-03-31
Project Status	Completed (Fiscal Year 2014)
Budget Amount *help	¥3,640,000 (Direct Cost: ¥2,800,000、Indirect Cost: ¥840,000) Fiscal Year 2014: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2013: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2012: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Keywords	雨水貯留水 / 細菌汚染制御 / アースプラス / 健康影響評価
Outline of Final Research Achievements	Water samples were collected periodically from 43 household rainwater tanks in Azumino, and tested for the presence of Legionella, coliforms and for the extent of heterotrophic bacteria. Only one sample yielded positive culture for Legionella during the investigation periods. In contrast, PCR assays gave positive results against each 12 samples in June and August, and 17 in October. The ceramic micro-beads coated with “Earth-plus” were proved to have bactericidal activities against Legionella, coliforms and heterotrophic bacteria. Immerging the ceramic micro-beads in the tanks yielded the favorable eradication of Legionella. Not only rapid-acting but also long-lasting bactericidal activities of the ceramic micro-bead were exhibited against L. pneumophila. However, time-dependent attenuation of the bactericidal activities were noted in the sustainability appraisal experiment. More reliable methods are needed for bacterial contamination measures in rainwater storage tanks.