An experimental study of gas nuclei-assisted hydrodynamic cavitation for aquaculture water treatment
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R E G UL A R P A P E R
• Chang Wei Kang Tandiono Tandiono Hafiiz Bin Osman • Fannon Lim
•
Xin Lu
•
Cary K. Turangan
•
Matthew Tan
•
An experimental study of gas nuclei-assisted hydrodynamic cavitation for aquaculture water treatment Received: 8 October 2019 / Revised: 10 March 2020 / Accepted: 15 April 2020 Ó The Visualization Society of Japan 2020
Abstract We present an experimental study on hydrodynamic cavitation generated by accelerating liquid through a series of constrictions in the presence of gas bubbles and explore its possible applications in water treatment with particular example in aquaculture industry. The formation of intense cavitation bubbles is visualized using a high-speed photography. The cavitation is initiated when a gas bubble moves towards a narrow cylindrical constriction where it accelerates, expands and then splits into smaller bubbles owing to the sharp pressure gradient of the liquid flow inside the constriction section. As the bubbles emerge downstream from the constrictions, they are exposed to a higher pressure region and collapse violently forming a cloud of bubbles. Smaller and more dispersed bubbles are produced by further passing the bubbles through a second series of constrictions. By introducing gas bubbles that serve as cavitation nuclei prior to the constriction, it is unnecessary to force the liquid flow below its vapor pressure to produce intense cavitation, thus enhancing the cavitation activities. We also present experimental evidences of a significant reduction of gram-negative Escherichia coli concentration after exposing them to the cavitation bubbles. Yet, the cavitation bubbles are found to be not sufficiently strong to lyse endospores Bacillus subtilis that are widely used in aquacultures. Keywords Hydrodynamic cavitation Bubble Disinfectant High-speed visualization
1 Introduction Water disinfection techniques, ranging from the simplest technique by simply boiling to the most advance systems by using both chemical (e.g. chlorination, electro-chlorination, ozonation, peracetic acid, and chlorine dioxide) and physical treatments (e.g. ultraviolet irradiation, ultraviolet with TiO2, deoxygenation, Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12650-020-00668-5) contains supplementary material, which is available to authorized users. T. Tandiono (&) C. W. Kang X. Lu C. K. Turangan Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore E-mail: [email protected] M. Tan JCU Centre for Sustainable Tropical Fisheries and Aquaculture (CSTFA), College of Science and Engineering, James Cook University, Singapore, Singapore H. B. Osman Research & Development, Sembcorp Marine Ltd, 80 Tuas South Boulevard, Singapore 637051, Singapore F. Lim School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK
T. Tandiono et al.
gas injection, and ultrasonic cavitation), have been used for water treatment in many industrial applications, such as for ba
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