Modelling of chemical kinetics in the presence of hydrodynamic cavitation for wastewater treatment applications

Abstract

The reaction rate of hydroxyl radicals with organic pollutants is about 108−1011 /mol-s, can degrade a wide range of pollutants. Intense bubble collapse during hydrodynamic cavitation can produce hydroxyl radicals, making it suitable for wastewater treatment. The current study introduces a numerical method of predicting the performance of a hydrodynamic cavitation reactor. Unlike most literature that considers cavitation volume as an indicator of effectiveness of hydrodynamic cavitation, the present approach considers local pressure variation, cavitation volume fluctuation, radical production and their inter-relations. The findings show that though an initial increase in the extent of cavitation, marked by a rise in cavity volume, leads to higher OH. radical production, the radical generation declines below an optimal cavitation number. The downstream recovery pressure also influences radical production. This numerical methodology, providing complete picture of radical production and its locations, will be very helpful for designing a new and more efficient cavitation reactor.