1988 Fiscal Year Final Research Report Summary
A study on the control of sewage activated sludge bulking
| Project/Area Number |
61550394
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
都市工学・衛生工学
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| Research Institution | University of Yamanashi |
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Principal Investigator |
KOHNO Tetsuro Dept. of Environmental Engineering, Faculty of Engineering, Yamanashi University, Associate Professor, 工学部環境整備工学科, 助教授 (50111779)
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| Co-Investigator(Kenkyū-buntansha) |
KAZAMA Futaba ibid, Assistant, 工学部環境整備工学科, 助手 (00115320)
NAKAYAMA Ooki ibid, Professor, 工学部環境整備工学科, 教授 (50020334)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Activated sludge / Bulking / Type II-3 / Type 021N / Physiology / Sulfur-bacteria / A / O operation |
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| Research Abstract |
The aim of the present study is to find a novel way in the control of bulking with special interest in sewage activated sludge. For this, the study was conducted both with isolates of Type II-3 which is the main causative organism for sewage, and with activated sludge.
<In axenic culture with isolates of Type II-3>
Type II-3 is gram-negative, and deposits both poly-phosphate and PHB. Oxidase is positive but catalase is positive or negative. Its unique nature is to deposit sulfur granules in the cell by oxidation of hydrogen sulfide and thiosulphate. Fifty-five strains were isolated in axenic culture from activated sludge. Morphology, physiology, and dissimilatory nutrition on inorganic sulphur compounds were clarified with eight isolates.
<Bulking control by means of A/O operation of activated sludge>
Bulking activated sludge by Type II-3 developed by continuous feeding of wastewater containing glucose and polypeptone as carbon sources was further cultivated under different modes of A/O operation to find the exact conditions to suppress filamentous bacteria including Type II-3 by observing both metabolisms of phosphate and organic matter, and the fate of each type of filamentous bacteria under microscopy. As the result, it was confirmed that A/O operation is a novel way to suppress filamentous bacteria when organic matter was simultaneously removed with the release of cellular poly-phosphate in the anaerobic phase. Although the reasons why filamentous bacteria are suppressed by A/O operation are still not fully understood, it was clarified that phosphate released under the anaerobic phase associates with suppression of filamentous bacteria including Type II-3, Sphaerotilus, and Thiothrix(Type II-10) by pure culture study. Its high concentration is toxic to their growth, and also release of phosphate lowers the pH of activated sludge suspensions to a range in which these filamentous bacteria are suppressed.
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