2007 Fiscal Year Final Research Report Summary
Study on evaluation methods for hygienic safety of activated sludge from sewage plants
| Project/Area Number |
17580292
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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 |
Boundary agriculture
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| Research Institution | Nihon University |
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Principal Investigator |
SUNAIRI Michio Nihon University, College of Bioresource Sciences, Associate professor (80196906)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAJIMA Mutsuyasu Nihon University, College of Bioresource Sciences, Professor (10059660)
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| Project Period (FY) |
2005 – 2007
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| Keywords | waste water treatment / activated sludge / adhesion / electrostatic interaction / Rhodococcus / extracellular polvsaccharide / enteric vius |
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| Research Abstract |
Since domestic wastewater could be contained pathogenic enteric viruses released from infected persons the knowledge of the viral behavior in wastewater purifying processes is important : it is, however, still poorly understood. We have reported that the adhesion of Poliovirus (Sabin 1 strain) to activated sludge samples taken from wastewater purifying plants and the mechanism of the adhesion. More than 10^8 particles adhered to one gram (wet) of activated sludge, and the adhered viral particles maintained infectivity for longer period of time and showed higher thermo-resistant than the free viral particles. The adhered viral particles were released by increase of salt concentration or alkaline pH buffer as infectious particles. Although the Poliovirus particles have 2 isoelectric points, one at approx. pH 4.3 (major population) and the other at approx. pH 7.2 (minor population), the particles adsorbed much more strongly to a cation-exchange chromatography column than to an anion-exchange one at pH 7.2 and chelating agents interfered with the viral adsorption to activated-sludge samples, suggesting that activated sludge adsorbed the viral particles mainly through electrostatic interaction, acting as a cation-exchange adsorbent, and that multivalent cations play an important role in the viral adsorption. In this research we analyzed non-specific adhesion mechanisms of microorganisms to activated sludge. We determined chemical structures of extracellular polysaccharides produced by strains belonging to the genus Rhodococcus, and analyzed effects of changes in their negative charges on the non-specific adhesion. Next, we examined didemnid ascidians and their symbonts to analyze adhesion and concentration mechanisms of microorganisms released from wastewater purifying plats to filter feeders.
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Research Products
(6 results)
