1995 Fiscal Year Final Research Report Summary
Development of Bioreactor System for the Treatment of Chromate Wastewater and the Recycle of Chromium using Chromate Reducing Bacteria Enterobacter cloacae HO-1
| Project/Area Number |
05558074
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
環境保全
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| Research Institution | Toyohashi University of Technology (1994-1995)
Yokohama National University (1993) |
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Principal Investigator |
FUJIE Koichi Toyohashi University of Technology, Department of Ecological Engineering, Professor, 工学部, 教授 (30134836)
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| Co-Investigator(Kenkyū-buntansha) |
OKUYAMA Fumihiko Nippon Kagaku Kogyo Ltd., Research and Development Division, Researcher, 研究員
SHIMADA Takeo Nippon Kagaku Kogyo Ltd., Rescarch and Development Division, General Manager, 本部長
OHTAKE Hisao Hiroshima University, Department of Fermentation Technology, Professor, 工学部, 教授 (10127483)
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| Project Period (FY) |
1993 – 1995
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| Keywords | Hexavalent chromium containing wastewater / Chromate-resistant and chromate-reducing bacteria / Enterobacter cloacae strain HO-1 / Bioreactor system / Mathematical model / Recycle of Chromium / Chromium ore residue |
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| Research Abstract |
A novel bioreactor system was developed for the simultaneous treatment of toxic and mutagenic hexavalent chromium (chromate) and high strength organic pollutants by introducing chromate-resistant and chromate-refucing bacteria Enterobacter cloacae strain HO-1. Growth and chromate reducing characteristics of E.cloacae HO-1 were extensively investigated. To enrich the active E.cloacae HO-1 in the bioreactor, the acrated cultivation with oxidation-reduction potential (ORP) control was successfully applied. Characteristics of the bioreactor system were studied to optimize its operating condition. Based upon the growth and chromate reducing kinetics of HO-1, a mathematical model to simulate the change of chromate removal rate per unit volume of bioreactor and that per unit cell mass under the fed-batch operation was proposed. Effects of repeated cultivation of HO-1 with ORP-controlled acration and the cumulative chromate reduction perunit cell mass on the microbial activity were investigated to represent the kinetic expression of chromate reduction. By using the mathematical model developed through the present research, relationship between the operating conditions and the chromate reduction rate in the bioreactor weas simulated and the model was verified by comparing with the observed data. Thus the optimal operating conditions to give the higher reduction rate and the longer operating interval with and without actated cultivation of HO-1 were extensively discussed. This bioreactor can be used for the treatment of chromate wastewater provided that some high concentration organic wastes are available. The specific rate of chromate reduction is as high as 500 mg-chromate/g-microbes.The rate of chromate reduction in the bioreactor is around 10-15 g-Cr^<6+>/m^3h. Chromium hydroxide, products of biological chromate reduction, can be recycled for green-color pigment after the incineration of the sludge removed from the effluent.
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