Chapter 24 - Process intensification in wastewater treatment: cavitation and hybrid technologies for organic pollutants

Abstract

This chapter highlights the cavitation and associated hybrid technologies along with various other conventional technologies like membrane separation, electrochemical processes, bioremediation etc., for treatment of wastewater effluents. These technologies mainly include the application of hydrodynamic and acoustic cavitation to the wastewater effluent. Wastewater effluent contains various degree of hazardous waste depending on the type of industry it has originated from. Treatment of wastewater by the application of advanced oxidation processes involves the generation of highly reactive hydroxyl free radicals which have potential capability to degrade highly toxic and hazardous organic pollutants. Cavitation technologies are the latest addition in wastewater treatment and have attracted research teams globally. Cavitation is simply defined as the phenomenon of formation, growth, and subsequent collapse of microbubbles which are often termed as cavities, in an extremely small fraction of times—usually within milliseconds—while releasing huge amounts of energy. Both acoustic/ultrasonic and hydrodynamic cavitation involves release of highly reactive free radicals which play a crucial role in the degradation of organic and inorganic pollutants. Several studies have established that cavitation-based hybrid techniques are far more versatile than conventional and other advanced oxidation processes that have stringent limitations and added disadvantages thus discouraging their wide application.