2004 Fiscal Year Final Research Report Summary
ENVIRONMENTAL PROTECTION USING CAVITATION
| Project/Area Number |
14350097
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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 |
Fluid engineering
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| Research Institution | Toyo University |
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Principal Investigator |
KATO Hiroharu Toyo University, Engineering, Professor, 工学部, 教授 (00010695)
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| Co-Investigator(Kenkyū-buntansha) |
USAMI Ron Toyo University, Engineering, Associate Professor, 工学部, 助教授 (80256776)
TAMURA Yoshiaki Toyo University, Engineering, Associate Professor, 工学部, 助教授 (40217203)
YAMAGUCHI Hajime University of Tokyo, Dept.of Systems Innovation, Professor, 工学系研究科, 教授 (20166622)
TOKUMITSU Kazuto University of Tokyo, Center for Collaborative Research, Assistant, 国際産学協同研究センター, 助手 (20180143)
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| Project Period (FY) |
2002 – 2004
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| Keywords | cavitation / jet / plankton / oil / emulsion / bacteria / organic compound / environment |
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| Research Abstract |
The high concentration of energy at the final stage of a cavitation bubble collapse causes very high pressure of more than 1 GPa. This sometime causes a detrimental effect to hydraulic machinery. However, we can use the high pressure for environmental protection. In this research project we performed the following 4 research subjects.
1.Killing Plankton
An abnormal increase in the amount of plankton in lakes and ponds can destroy their ecological environment. Another important subject is the discharge of ballast water from ocean-going ships. The ballast water contains plankton and fish eggs. They may destroy the ecological environment, when discharged thousands miles away from where they live. It was found that the cavitating jet with a target body was effective to killing plankton.
2.Dispersing Spilled Oil
Oil spill accidents have a disastrous effect on the ocean environment. Mechanical recovery of oil is the most desirable method. But, it can become difficult for various reasons, such as
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bad weather. The oil dipersion is the second-best solution, and dispersants are used. However, the dispersant may cause side effects. The dispersion of oil by cavitating jet is a unique and effective method, which was newly developed in the present project.
3.Sterilization of Bacteria
Sterilization of bacteria has been one of the most important procedures in human life. Heating is the most popular and common method of sterilization. However, it needs considerable amount of energy, and sometimes the nature of the material to be sterilized becomes worse. Chemicals are other popular sterilization method, but the chemicals may cause side effects to human body. The cavitaing flow is effective for the sterilization of bacteria. We tested two different types of bacteria, the Bacillus Subtilis as a typical example of the Gram-positive bacteria, and the Escherichia Coli as a typical example of the Gram-negative bacteria.
4.Oxidation of Organic Compounds
The cavitating jet is also effective for oxidation of harmful organic compounds. We performed systematic experiments for four organic compounds, 1,4-dichlorobenzene, biphenyl, dibenzofuran, and dibenzo-p-dioxin. It was found that the decomposition rate increased almost linearly with increasing injection pressure and with decreasing cavitation number. Less
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