Generation of large-capacity discharge plasma with seawater, and sterilization of bacteria in ballast water

2020 Fiscal Year Final Research Report

• Project/Area Number: 17K14636
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Power engineering/Power conversion/Electric machinery
• Research Institution: Iwate University
• Principal Investigator: Masahiro Akiyama 岩手大学, 理工学部, 准教授 (50611430)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: パルスパワー / バラスト水 / 海水 / 高電圧

Outline of Final Research Achievements

Underwater discharge was performed using a pulse power generator with a shot of 0.5 j. At 500 shots / sec, the electron temperature was 7841.8 K and the electron density was 6.0 × 10^17.The maximum voltage was about 25 kV, the maximum current was about 20 A, and the pulse width was about 3 μm. The measurement result of H2O2 was 0.732 mg / L at 45,000 μS / cm at 150,000 shots.
As a result of treating E. coli using a dielectric barrier discharge, the standard set by the IMO was cleared. And, the underwater discharge was also close to the standard value. Similarly, for Enterococci and Vibrio sp., number of colonies could be reduced by increasing the number of shots. In the plankton experiment, underwater discharge was able to remove up to 0 animals.

Free Research Field

パルスパワー

Academic Significance and Societal Importance of the Research Achievements

水が関与する放電プラズマ現象は、水中放電、沿面放電、泡の中での放電等多くの研究がなされ、水処理への応用もなされている。しかしながら、海水等、高い導電率を持つ水が関与する放電プラズマの研究は、バラスト水処理、温泉水処理等多くの応用があるにもかかわらず、その難しさからほとんど行われていない。本研究によって、放電プラズマによりIMOが定めるバラスト水排出基準の5種類中4種類に関して新たな処理の可能性を見出せた。