| Project/Area Number |
09650598
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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 |
Civil and environmental engineering
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| Research Institution | NATIONAL INSTITUTE FOR ENVIRONMENTAL STUDIES |
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Principal Investigator |
XU Kaiqin Water & Soil Div., Natl. Inst. for Environ. Studies, Senior Researcher, 水土壌圏環境部, 主任研究員 (20250722)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIMURA Osamu Faculty of Engineering, Tohoku University, Assoc. Professor, 大学院・工学研究科, 助教授 (80208214)
SUDO Ryuichi Faculty of Engineering, Tohoku University, Professor, 大学院・工学研究科, 教授 (70109916)
INAMORI Yuhei Regional Environ. Div., Natl. Inst. for Environ. Studies, Leader, 地域環境研究グループ, 総合研究所官 (10142093)
YAMADA Kazuhiro Faculty of Engineering, Tohoku University, Lecture, 大学院・工学研究科, 講師 (30250723)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1998: ¥800,000 (Direct Cost: ¥800,000)
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| Keywords | River ecosystem / Pollutant load / Dissolved oxygen / Nitrogen / Biotope / Water purification / Riffles and pools / 河川生態系 / 瀬と渊 / 硝化細菌 |
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| Research Abstract |
The objective of this is study was to investigate the behavior of nitrogenous biological oxygen demand in river ecosystem, to search a method to create an ecological river environment through the biotope method, to clarify the relationship between river structure and the water purification function, and the role of riffles and pools in river water purification systems. The results obtained can be summarized as follows :
1) Nitrogenous biological oxygen demand (N-BOD) was detected in high frequency in rivers if the effluent from the wastewater treatment plant flows into the rivers, especially, when C/N ratio is low, NH4-N concentration and water temperature are high. This result suggested that the flow of the effluent from sewer system might have negative impact on the river ecosystem due to the defect of DO in the river especially in the pools.
2) It was predicted from a simple simulation model based on the laboratory experimental results that the DO concentration in the pools of the river may decrease to 4 mg/l if the nitrogen compound is high. In order to keep the DO concentration more than 7.5mg/l in pools, it is necessary to decrease the NH4-N concentration less than 0.5mg/l.
3) To maintain a sound river ecosystem environment, it is important to use the ecological river improvement and natural diverse river restoration methods such as biotope and ecological engineering. It is effective to create riffles and pools in strait river banks to improve river water purification function. Riffles and pools play an important role in river ecosystem not only for water purification but also for the habitat of microorganisms.
4) It was proved that to use the purification blocks and nets to create riffles and pools in the river channels, effective removals of organic matter and nitrogen can be expected.
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