Fundamental study of sterilization effects on marine Vibrio sp. in a cylindrical water chamber with supply of only underwater shock waves

Jingzhu Wang; Akihisa Abe; Yiwei Wang; Chenguang Huang

doi:10.1016/j.ultsonch.2017.11.047

Fundamental study of sterilization effects on marine Vibrio sp. in a cylindrical water chamber with supply of only underwater shock waves

Ultrason Sonochem. 2018 Apr:42:541-550. doi: 10.1016/j.ultsonch.2017.11.047. Epub 2017 Dec 22.

Authors

Jingzhu Wang¹, Akihisa Abe², Yiwei Wang³, Chenguang Huang³

Affiliations

¹ Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, No. 15 Beisihuanxi Road, Haidian Distinct, Beijing 100190, China; School of Engineering Science, University of Chinese Academy of Sciences, China. Electronic address: wangjingzhu@imech.ac.cn.
² Graduate School of Maritime Sciences, Kobe University, 5-1-1 Fukaeminami-machi, Kobe 658-0022, Japan.
³ Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, No. 15 Beisihuanxi Road, Haidian Distinct, Beijing 100190, China; School of Engineering Science, University of Chinese Academy of Sciences, China.

PMID: 29429701
DOI: 10.1016/j.ultsonch.2017.11.047

Abstract

The effect of shock sterilization on marine Vibrio sp. is investigated by carrying out a bio-experiment based on a bubble-shockwave interaction. In the experiments, underwater shock waves with different strength and frequencies are produced by a high-voltage power supply in a cylindrical water chamber. The bio-experimental results show marine Vibrio sp. is completely inactivated in a short time by a 1.0-Hz electric discharge. However, a high sterilization effect requires a strong and high frequency of the bubble motion, and it also depends on the lifetime of the bubble. Subsequently, by an experiment with an air gap to prevent the underwater shock waves entering the cell suspension, it is found that the introduction of a strong shock pressure is not entirely required to obtain the effective sterilization. On the other hand, the direct effect of the sterilization by rebound shock wave resulting from the bubble-shock wave interaction is examined in the experiments. The results suggest that free radicals mainly contribute to killing marine bacteria, and direct mechanical effects of the bubble motion are not responsible. In addition, the creation of the OH radical is indirectly confirmed by measuring the H₂O₂ concentration. Finally, the Herring equation is solved to investigate the condition of free radical generation when considering the effect of thermal conductivity at the bubble interface. As a result, the effective sterilization conditions based on the bubble-shock wave interaction are clearly obtained.

Keywords: Bubble-shock wave interaction; Cylindrical water chamber; Free radicals; Rebound shock wave; Ship’s ballast water; Sterilization effect.