Hydrodynamic cavitation as an efficient water treatment method for various sewage:- A review

Abstract

With the development of industry and the rapid growth of population, the current water treatment technologies face much challenges. Hydrodynamic cavitation as a green and efficient means of water treatment method has attracted much attention. During the hydrodynamic cavitation, enormous energy could be released into the surrounding liquid which causes thermal effects (local hotspots with 4,600 K), mechanical effects (pressures of 1,500 bar) and chemical effects (hydroxyl radicals). These conditions can degrade bacteria and organic substance in sewage. Moreover, the combination of hydrodynamic cavitation and other water treatment methods can produce coupling effect. In this review, we summary the methods of hydrodynamic cavitation and the performance of water treatment for different types of sewage. The application of hydrodynamic cavitation reactors with different structures in water treatment have also been evaluated and discussed. The design and optimization of high-performance hydrodynamic cavitation reactor is the most crucial issues for the application of hydrodynamic cavitation in water treatment. Finally, recommendations are provided for the future progress of hydrodynamic cavitation for water treatment.

Biologically Structured Water (BSW) - A Review (Part 3): Structured Water (SW) Generation, BSW Water, Bioenergetics, Consciousness and Coherence

“…Hydrodynamic cavitation occurs when the local pressure in water drops sharply below the saturated vapor pressure of the liquid, creating microbubbles of gas vapor. The microbubbles implode or cavitate as the local liquid pressure returns to normal [48][49][50][51]. A high-energy ultrasonic pulse is released as the gas bubbles expand and implode.…”

A Comprehensive Review on Pulp and Paper Industries Wastewater Treatment Advances

“…• , which can all be extremely suitable for the oxidation of pulp and paper industry pollutants. 139 Due to the lower intensity of cavitation, HC is seen to have lower degradation rates in wastewater treatment applications. Hybrid treatment methods can enhance HC's efficacy by coupling it with other oxidants such as H 2 O 2 , Fenton's reagent, and ozone.…”

“…As HC occurs, the local pressure inside the fluid drops sharply below the saturated vapor pressure, resulting in gas dissolving in water and being separated, which results in the generation of cavitation bubbles. When a bubble collapses, extreme conditions can cause the chemical bonds within the water molecules to break and form radicals such as the hydroxyl radical OH • as well as the hydrogen peroxide radical OH 2 • , which can all be extremely suitable for the oxidation of pulp and paper industry pollutants …”

Effect of Dissolved Carbon Dioxide on Cavitation in a Circular Orifice

“…Acoustic cavitation (where pressure variations are induced via ultrasonication) is used to erode and break kidney stones [4] or to clean the surfaces of root canals, filter membranes, surgical equipment, or electronic substrates [5]. Hydrodynamic cavitation has found applications in water purification, the recycling of waste, and process water and material recycling [6][7][8][9][10]. As gases dissolved in the liquid phase evolve, they can affect cavitation inception [11,12] and the subsequent dynamics of the cavitation bubbles, including, for example, peak pressures during a bubble collapse.…”