COD removal from sucrose solution using hydrodynamic cavitation and hydrogen peroxide: a comparison between Venturi device and orifice plate

Abstract

The aim of the current study is to compare the chemical oxygen demand (COD) removal efficiency of a Venturi device to that of an orifice plate. The inlet pressure in the devices was optimized and the degradation kinetics was analyzed. In addition, the synergistic effect resulting from the combination between cavitation and H2O2 was investigated. An experimental apparatus was built to achieve these goals. A sucrose solution and an effluent from a sucrose-based soft drink industry were treated. Results showed that the Venturi device recorded 90% COD removal efficiency after three treatment minutes. On the other hand, the orifice plate recorded 90% COD removal efficiency after 9 min. The degradation kinetics-reaction order was 3.5, except for the highest Venturi inlet pressure (7.3 bar), which led to coalescence of cavities and to reduced degradation rate. The synergistic coefficient (Sc) was 185.20 and showed that the hybrid process (HC + H2O2) was much more efficient than the cavitation process applied alone. The high COD concentration in the effluent generated by the soft drink industry (2,512.8 mg L-1) was significantly decreased by 72%. The combined use of cavitation and Venturi has significant potential to remove high organic matter concentrations in short treatment periods.

Removal of natural organic matter in waters using hydrodynamic cavitation and hydrogen peroxide (HC-H2O2)

“…This outcome can be explained by the fact that the HC/ H2O2 combination generates more reactive species, reduces mass transfer resistance, and increases turbulence generation (RAUT-JADHAV et al 2013). Other authors have also reported pollutant degradation increase in case of HC combined with H2O2 (ALVES et al, 2019;JOSHI and GOGATE, 2019;SAXENA et al, 2018;MACHADO et al, 2020). It is observed that system efficiency is increased when cavitation is combined with the decantation phenomenon.…”

“…Hydrodynamic cavitation (HC) is one of the alternatives emerging as efficient to remove water pollutants (BATISTA; ANHÊ; GONÇALVES, 2017;ALVES et al, 2019;MACHADO et al, 2020). It is generated by liquid passage through physical constriction (cavitation chamber), such as an orifice plate and a Venturi.…”

“…Another factor influencing pollutant removal efficiency lies on the geometry of the cavitation chamber. Alves et al (2019) have shown that the Venturi chamber is more efficient…”

Synergistic bromothymol blue dye degradation with hydrodynamic cavitation and hydrogen peroxide (HC-H2O2)

“…Based on these results, degradation efficiency is significantly reduced at low oxidant concentrations. Alves et al (2019) used hydrodynamic cavitation to analyze COD reduction efficiency of an effluent whose main constituent was sucrose. Based on their results, 90% removal efficiency was observed when peroxide/sucrose molar ratio was equal to 20, cavitation time was 25 min and inlet pressure was 4.0 bar.…”

Quantitative characterization of volume of cavities in hydrodynamic cavitation device using computational fluid dynamics

“…The HC phenomenon has been applied in numerous applications of sanitary and environmental engineering (involving physical-chemical processes), from water treatment (DULAR et al, 2016;BAGAL;, wastewater containing pesticides (PATIL et al, 2014), drugs dissolved in water ZUPANC et al, 2013), effluent from tannery waste (SAXENA et al, 2018), effluent from soft drink industry (ALVES et al, 2019), to dye removal (RAJORIYA et al, 2017;RAJORIYA et al, 2018) and algae removal (BATISTA et al, 2017). In production processes there are reports over the use of HC ranging from the synthesis of biodiesel (MADDIKERI et al, 2014), pre-treatment of biomass (HILARES et al, 2017) to the production of nanoemulsion (CARPENTER et al, 2017).…”