2005 Fiscal Year Final Research Report Summary
Solubilzation of dewatered sludge cake and its application to production of secondary methabolite
| Project/Area Number |
15360482
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Recycling engineering
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| Research Institution | Niigata University |
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Principal Investigator |
YAMAGIWA Kazuaki Niigata University, Institute of Science and Technology, Professor, 自然科学系, 教授 (60200606)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Sludge treatment / Biopesticide / Solubilization / Excess activated sludge / Dewatered cake / Solid fermentation / Sludge recycle |
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| Research Abstract |
The effectiveness of sludge pretreatment for production of biopesticide produced by Bacillus thuringiensis was investigated. TOC release ratio, defined by the ratio of solubilized TOC to MLVSS concentration, and the energy efficiency for sludge slurry and cake were evaluated for various pretreatments such as micro bubble expansion, freeze/thaw, ultrasonic irradiation, ozone, hydrogen peroxide, microwave irradiation, and autoclaving. The TOC release efficiencies of slurry by freeze/thaw treatment were comparable to those by ultrasonic irradiation. The micro bubble expansion using carbon dioxide gas gave the lowest TOC release ratio but the highest energy efficiency. The TOC releases from filtered and dewatered cakes by the pretreatments were also evaluated. The TOC release ratios decreased with decreasing water content of cake. The effects of sludge pretreatments on growth and sporulation of B.thuringiensis were further investigated. The ozonation, ultrasonic irradiation and hydrogen peroxide treatments gave lower maximum spore concentration both in liquid and solid-state fermentations in spite of high TOC release ratio. The micro bubble expansion and freeze/thaw treatments gave higher maximum spore concentration although the TOC release rates were low. Assimilability of organic substances was considered to be one of the critical parameters to select the sludge pretreatment method for production of biopesticide.
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Research Products
(4 results)
