2002 Fiscal Year Final Research Report Summary
Production of Biodegradable Plastics by Excess Activated Sludge
| Project/Area Number |
11217203
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | The University of Tokyo |
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Principal Investigator |
NINO Takashi The University of Tokyo, Graduate School of Frontier Sciences, Professor, 大学院・新領域創成科学研究科, 教授 (60166098)
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| Co-Investigator(Kenkyū-buntansha) |
SATOH Hiroyasu The University of Tokyo, Graduate School of Frontier Sciences, Associate Professor, 大学院・新領域創成科学研究科, 助教授 (90251347)
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| Project Period (FY) |
1999 – 2002
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| Keywords | activated sludge / excess sludge / biodegradable plastic / polyhydroxyalkanoates / 3-hydroxy-2-methylvalerate / anaerobic-aerobic activated sludge / microbial population |
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| Research Abstract |
Stability of PHA production by activated sludge was evaluated. PHA accumulation capacity (PAC), the maximum PHA content attained in a batch experiment under optimized condition for PHA production, was used as the indicator of PHA production performance. Activated sludge treating synthetic wastewater attained PAC of 68%, while such high level of PAC was not maintained for long. It was Indicated that attaining PAC of 40〜50% is reproducible. Acetate concentration in the synthetic wastewater was found to positively affect PAC. In the concentration or lower pH condition. The PCR-DGGE method was applied to clarify the stability or dynamics of microbial population structure inactivated sludge. The dynamic change of population structure observed by PCR-DGGE was accompaniec the change of metabolic behavior of activated sludge, indicating that microbial population change is causing the unstability of PHA production performance. The PCR-DGGE method indicated that the bacteria that produce PHA containing 3-hydroxy-2-methlbutyrate (3H2MV), the component which has been reported only in activated sludge, most probably belong to Proteobacteria beta subclass with close phylogenetic relationship with Rhodocyclus group. In order to maintain PAC at a high level stably, it is needed to stabilize bacterial community structure. Fundamental investigation is needed to clarify the cause of microbial population change and further to stabilize population structure in activated sludge. As the last step of the study, the effect of oxygen supply to the production of PHA containing 3H2MV unit was investigated to promote its production. The oxygen supply didd enhanced PHA production, but rather resulted in the reduction of 3H2MV in its composition.
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