Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney 2052, Australia.
UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu 214200, P.R. China.
Environ Sci Technol. 2022 Apr 5;56(7):4377-4385. doi: 10.1021/acs.est.1c07694. Epub 2022 Mar 23.
The efficacy of oxidation of recalcitrant organic contaminants in municipal and industrial wastewaters by ozonation is influenced by chemical reaction kinetics and hydrodynamics within a reactor. A 3D computational fluid dynamics (CFD) model incorporating both multiphase flow and reaction kinetics describing ozone decay, hydroxyl radical (OH) generation, and organic oxidation was developed to simulate the performance of continuous flow ozonation reactors. Formate was selected as the target organic in this study due to its well-understood oxidation pathway. Simulation results revealed that the dissolved ozone concentration in the reactor is controlled by rates of O(g) interphase transfer and ozone self-decay. Simulations of the effect of various operating conditions showed that the reaction stoichiometric constraints between formate and ozone were reached; however, complete utilization of gas phase ozone was hard to achieve due to the low ozone interphase mass transfer rate. Increasing the O(g) concentration leads to an increase in the formate removal rate by ∼5% due to an enhancement in the rate of O(g) interphase mass transfer. The CFD model adequately describes the mass transfer occurring in the two-phase flow system and confirms that O(g) interphase mass transfer is the rate-limiting step in contaminant degradation. The model can be used to optimize the ozone reactor design for improved contaminant degradation and ozonation efficiency.
臭氧氧化法处理城市和工业废水中难降解有机污染物的效果受到反应器内化学反应动力学和流体动力学的影响。本研究开发了一种 3D 计算流体动力学（CFD）模型，该模型结合了多相流和描述臭氧衰减、羟基自由基（OH）生成和有机氧化的反应动力学，以模拟连续流动臭氧氧化反应器的性能。由于甲酸具有明确的氧化途径，因此选择其作为目标有机物。模拟结果表明，反应器中的溶解臭氧浓度受 O(g)相间传质速率和臭氧自分解速率控制。对各种操作条件的影响进行了模拟，结果表明达到了甲酸和臭氧之间的反应化学计量约束，但由于气相臭氧的相间传质速率较低，难以实现完全利用。增加 O(g)浓度可使甲酸的去除率提高约 5%，这是由于 O(g)相间传质速率的提高所致。CFD 模型充分描述了两相流系统中发生的传质过程，并证实 O(g)相间传质是污染物降解的限速步骤。该模型可用于优化臭氧反应器设计，以提高污染物降解和臭氧效率。
