Numerical modeling of mass transfer processes coupling with reaction for the design of the ozone oxidation treatment of
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RESEARCH ARTICLE
Numerical modeling of mass transfer processes coupling with reaction for the design of the ozone oxidation treatment of wastewater Hong Li1,2, Fang Yi1,2, Xingang Li1,2, Xin Gao (✉)1,2 1 School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China 2 National Engineering Research Center of Distillation Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
© Higher Education Press 2020
Abstract A computational model for an ozone oxidation column reactor used in dyeing wastewater treatment is proposed to represent, simulate, and predict the ozone bubble process. Considering the hydrodynamics, mass transfer, and ozone oxidation reaction, coupling modeling can more realistically calculate the ozone oxidation bubble process than the splitting methods proposed in previous research. The modeling is validated and shows great consistency with experimental data. The verified model is used to analyze the effect of operating conditions, such as the initial gas velocity and the ozone concentration, and structural conditions, such as multiple gas inlets. The ozone consumption is influenced by the gas velocity and the initial ozone concentration. The ozone’s utilization decreases with the increasing gas velocity while nearly the same at different initial ozone concentrations. Simulation results can be used in guiding the practical operation of dyeing wastewater treatment and in other ozonation systems with known rate constants in wastewater treatment. Keywords ozone, wastewater treatment, numerical simulation, mass transfer
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Introduction
As drinking water shortage is becoming increasingly serious due to climate change and rapid population growth [1], wastewater treatment has recently drawn increasing interest from researchers [2]. Organic compounds, such as p-nitrophenol and cresol, are common pollutants in oil Received February 23, 2020; accepted May 25, 2020 E-mail: [email protected]
refineries, petrochemicals, textile dyeing, and other industrial processes [3], posing serious threats due to their high toxicity and stability [4]. In this study, p-nitrophenol is selected as the representative organic pollutant because it is widely used in processing various industrial products, remains in wastewater, and is toxic to humans [5]. Oxidation-reduction reactions, membrane separation, and biochemical degradation are all common treatment methods for removing organic substances [6]. Meanwhile, ozonation is studied here due to the high disinfection and oxidation properties of ozone [7]. Furthermore, ozone is also shown to transform high molecular weight compounds into smaller, more bioavailable fractions [8], which are beneficial for other treatments, such as biofiltration. However, ozone is mainly produced through high-cost methods, such as ultraviolet ray, highvoltage corona discharge, and proton exchange membrane water electrolysis [9]. The utilization of ozone must be increased to reduce the total cost, requiring an accurate quan
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