A study on Improvement of an Urban Lake by Bottom-Filtration

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 12650555
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Civil and environmental engineering
• Research Institution: Fukuoka University
• Principal Investigator: YAMASAKI Koreyoshi Fukuoka University, Faculty of Engineering, Professor, 工学部, 教授 (00038100)
• Co-Investigator(Kenkyū-buntansha): WATANABE Ryoichi Fukuoka University, Faculty of Engineering, Research Assistant, 工学部, 助手 (50299541)
• Project Period (FY): 2000 – 2002
• Keywords: Bottom-Filtration / Experiment / Field observation / Water quality improvement / Eutrophic lake / Simulation

Research Abstract

We have carried out the bench-scale experiments and the simulations on Bottom-Filtration for improvement of water quality in eutrophic lakes. "Bottom-Filtration" means filtration of lake water through the filter which is installed on the bottom of the lake, and the filtrate is circulated to the lake water. In the experiment we used decomposed granite and Kuroboku Soil (Ando soil) as the filter media. And circulation rates were set as no circulation. 14 days and 3.5 days. We found that water quality becomes finer as higher the circulation rate, but the filter media do not show much difference. Introducing mass transport by convection to the filter, we remake the Water-Sediments Eutrophication Model, and have carried out the simulation. The results of the experiments and simulations show quite good accordance. The long term simulation by the model can show the best circulation rate according to the target of the water quality of a lake.