Abstract
Cavitation phenomena are associated with the formation, growth and the collapse of microbubbles and consequently, to the generation of very high pressures, shear stresses and temperatures, locally. Thanks to the cited features, the application of cavitation is a reliable tool for cell damage and hence disruption. In this paper a theoretical model for quantifying the mechanical effect of hydrodynamic cavitation (HC) and acoustic cavitation (AC) in killing micro-organism is reported. A physical model accounting for bubble dynamics, fluid turbulence, shear stress and pressure pulse generated from cavity collapse is developed, aimed at calculating the turbulent shear generated and the extent of microbial disinfection. The theoretical results are compared with the mechanical resistance of microbial cells in order to estimate the damaging effect.
Numerical results provide a practical tool for the estimation of process efficacy and parameter optimization, both for HC and AC devices. The effect of parameters is estimated and typical experiments from the pertinent literature are simulated in order to estimate the treatment efficiency. Results are in agreement with the related; moreover, from the energy efficiency point of view, it was observed that HC is almost an order of magnitude more energy efficient than AC.
