ABSTRACT
Treatment of organic contaminants in wastewater has always been a great challenge in terms of efficiencies and costs. Emerging technologies such as advanced oxidation processes (AOPs), which harness the reactivity of hydroxyl and or peroxygen radicals for organic contaminant mineralization, have gained significant attention for many years. However, the generation of the hydroxyl or peroxygen radicals using catalytic or photocatalytic processes are often cost-prohibitive. Cavitation methods, though considered a nuisance in flow systems, have shown great potential in wastewater treatment. In particular, hydrodynamic cavitation, which is the formation of cavitation bubbles when a liquid is subjected to dynamic pressure reduction due to the presence of constriction in the flow system, has generated substantial interest due to their efficacy. The cavity created downstream of constriction creates intense turbulence, liquid streaming at the micro-level as well as hot spots, which in turn generates significant amounts of hydroxyl radicals required for organic pollutant degradation. The chapter discusses the basics of hydrodynamic cavitation, its use in combination with other AOPs, and their effectiveness in the mineralization of organic contaminants in wastewater. The chapter also discusses the reactors used in hydrodynamic cavitation, the effect of process parameters, and the scalability of the process.
