Computational Fluid Dynamics simulation of two-phase flow and dissolved oxygen in a wastewater treat

“This study presents a computational fluid dynamics (CFD) model of an aerated wastewater treatment oxi-dation ditch, taking into account gas-liquid flow, oxygen mass transfer and dissolved oxygen. Especially,the effect of the bubble size distribution (BSD) and the biochemical oxygen demand (BOD) distributionon the dissolved oxygen (DO) distribution has been considered. Species transport modelling predicts theDO and BOD distribution. De-oxygenation of local dissolved oxygen by BOD is modelled by an oxygensink that depends on the local BOD concentration. Bubble coalescence and breakup models predict theBSD. The behaviour of the ditch is non-ideal, which is indicated by the residence time distribution (RTD),heterogeneous flow pattern and DO distribution. The parameters with the greatest influence on the dis-solved oxygen are the BOD and bubble size. There is good agreement between the numerical simulationand the observations of flow pattern and measurements of mean DO. This study identifies that the BODdistribution and the BSD are important parameters for accurately predicting the DO distribution andwhich have been mostly neglected in the public research.”

(Citation: Matko, T., Chew, J., Wenk, J., Chang, J., Hofman, J.A.M.H. – Computational Fluid Dynamics simulation of two-phase flow and dissolved oxygen in a wastewater treat – Process Safety and Environmental Protection 145 (2021)p, 340–353 – DOI: 10.1016/j.psep.2020.08.017)

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