Abstract This study presents a computational fluid dynamics (CFD) model of an aerated wastewater treatment oxidation 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) distribution on the dissolved oxygen (DO) distribution has been considered. Species transport modelling predicts the DO and BOD distribution. De-oxygenation of local dissolved oxygen by BOD is modelled by an oxygen sink that depends on the local BOD concentration. Bubble coalescence and breakup models predict the BSD. 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 dissolved oxygen are the BOD and bubble size. There is good agreement between the numerical simulation and the observations of flow pattern and measurements of mean DO. This study identifies that the BOD distribution and the BSD are important parameters for accurately predicting the DO distribution and which have been mostly neglected in the public research.

中文翻译：

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“污水处理氧化沟中两相流和溶解氧的计算流体动力学模拟”

摘要 本研究提出了曝气废水处理氧化沟的计算流体动力学 (CFD) 模型，同时考虑了气液流动、氧传质和溶解氧。尤其考虑了气泡大小分布（BSD）和生化需氧量（BOD）分布对溶解氧（DO）分布的影响。物种迁移模型预测 DO 和 BOD 分布。BOD 对局部溶解氧的脱氧由取决于局部 BOD 浓度的氧吸收器建模。气泡合并和破裂模型预测 BSD。沟渠的行为是非理想的，这由停留时间分布 (RTD)、异质流型和 DO 分布表明。对溶解氧影响最大的参数是 BOD 和气泡大小。数值模拟与流动模式的观察和平均溶解氧的测量之间有很好的一致性。本研究发现，BOD 分布和 BSD 是准确预测 DO 分布的重要参数，但在公共研究中却大多被忽视。