Simulation of FBR-Fenton/GAC process for recalcitrant industrial wastewater treatment with a computational fluid dynamics-kinetic model framework. (15th September 2021)

• Record Type: Journal Article
• Authors: Wu, M.Y.; Cai, Q.Q.; Xu, H.P.; Ong, S.L.; Hu, J.Y.
• Is Part Of: Water research. Volume 203(2021)
• Publication Date: 2021-09-15
• Subjects: Computational fluid dynamics -- Fluidized bed reactor -- FBR-Fenton -- GAC -- Reverse osmosis concentrate -- Organics removal; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2021.117504
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Liquid-solid FBR-Fenton/GAC process simulation with CFD-kinetic model Model accurately predicted COD removal in industrial ROC treatment Superficial liquid velocity had negligible impact on COD removal efficiency Homogenous Fenton mainly occurred in the upper liquid region GAC adsorption and GAC/H2 O2 reaction took place in fluidized bed region Abstract: An integrated computational fluid dynamics (CFD)-kinetic model framework was developed to numerically describe the hydrodynamic and kinetic phenomena in a liquid-solid two phases Fluidized-bed reactor Fenton/granular activated carbon (FBR-Fenton/GAC) system. The model obtained excellent accuracy for predicting chemical oxygen demand (COD) removal in reverse osmosis concentrate (ROC) treatment under different operation conditions. Hydrodynamic evaluation demonstrated that under the quasi-steady state, the GAC particles were uniformly circulated in the bed region with two pairs of counter-rotating recirculation cells, and a clear interface layer formed between the solid and the liquid phases. Superficial liquid velocity highly affected the fluidized bed expansion and solid volume fraction, while its impact on the overall COD removal efficiency was negligible. Chemical evaluation revealed that GAC/H2 O2 catalytic reaction enhanced the OH production in FBR-Fenton/GAC process by 2.7 folds as compared to homogenous Fenton process. Fenton reaction mainly occurred in the upper liquid region and its kinetics for OH generation significantly diminished by 75% within the first 10 min. GAC/H2 O2 reaction took place in the fluidized bed region for continuous OH generation with a relatively stable rate from 1.21 × 10 −6 to 0.60 × 10 −6 M/s. Along the ROC treatment with FBR-Fenton/GAC process, the simulated COD degradation rate decreased along the reaction time with 2.05 × 10 −6 M/s and 2.93 × 10 −7 M/s at 2 min and 60 min, respectively. Faster COD removal was attained in the fluidized bed region due to combining effects of OH oxidation and GAC adsorption. The overall predicted COD concentration reduced from 122 to 35 mg/L, OH oxidation and GAC adsorption contributed 59% and 41%, respectively, to the total COD removal. Graphical abstract: Image, graphical abstract