2001 Fiscal Year Final Research Report Summary
Bioremediation System for Heavy Metal -Contaminated Soils Using Bacteria Associated with the Sulfur Cycle
| Project/Area Number |
12680575
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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 |
環境保全
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| Research Institution | Osaka Prefecture University |
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Principal Investigator |
KONISHI Yasuhiro Osaka Prefecture University, Graduate School, Professor., 大学院・工学研究科, 教授 (90167403)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Contaminated Soils / Heavy Metals / Bioremediation / Cycle of Sulfur / Phototrophic Bacteria / Sulfate-Raducing Bacteria / Sulfur Bacteria / Bioleaching |
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| Research Abstract |
In this report we describes a bioremediation system of soils contaminated with heavy metals, in which the sulfur cycle (metal sulfide → sulfate → hydrogen sulfide → elemental sulfur) is artificially constructed using several bacteria associated with the sulfur cycle, and the microbial sulfur transformations are utilized for the leaching of heavy metals from contaminated soils and for the post-treatments of the bioleaching residue. In the leaching of contaminated soils, the sulfur-oxidizing. bacterium Acidianus brierleyi was found to solubilize heavy metals from sulfides (pyrite and sphalerite) contained in soils. In the biological downstream processing, sulfate ions accumulated in the leach solution were biologically reduced to hydrogen sulfide through the use of the sulfate-reducing bacterium Desulfotomaculum auripigmentum. After that, the biogenic hydrogen sulfide was oxidized to elemenal sulfur using the chemoautotrophic bacterium Thiobacillus denitrificans, and the formed elemental sulfur was recovered as a precipitate. Batch tests were performed to obtain rate data and optimize various process parameters for the individual bioprocesses such as the bioleaching of metal sulfides and the bioconversion of sulfate to elemental sulfur via hydrogen sulfide. The rate data indicated that the bioleaching process was the rate-determining step (the slowest step) in the proposed biotreatment system. Under the conditions determined as optimum for the bioleaching with A. brierleyi, it took a week to achieve high extractions (greater than 80 % leaching) of heavy metals from sphalerite and pyrite in contaminated soils.
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Research Products
(4 results)
