Study on two operating conditions of a full-scale oxidation ditch for optimization of energy consumption and effluent quality by using CFD model

Yang, Yin; Yang, Jiakuan; Zuo, Jiaolan; Li, Ye; Shu, He; Yang, Xiaofan; Zhang, Kai

doi:10.1016/j.watres.2011.04.007

Cited by 65 publications

(41 citation statements)

References 17 publications

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“…In more recent work, Yang et al (2011) developed CFD simulations based on a mixture gas-liquid model, which were used to optimize oxygen transfer in a fullscale multichannel oxidation ditch equipped with surface rotors and submerged mixers. Additional transport equations representing oxygen transfer and BOD removal were implemented.…”

Section: Previous Modeling Approachesmentioning

confidence: 99%

Towards a robust CFD model for aeration tanks for sewage treatment – a lab-scale study

Karpinska

Bridgeman

2017

Engineering Applications of Computational Fluid Mechanics

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Detailed insight into the hydrodynamics of aeration tanks is of crucial importance for improvements in treatment efficiency, optimization of the process design and energy-efficient operation. These factors have triggered increasing interest in the use of Computational Fluid Dynamics (CFD) to evaluate performance of wastewater treatment systems. Whilst factors such as incorrect input assumptions, poor model choice and excessive simplifications have been recognized as potential sources of output errors, there remains a need to identify the most robust strategy to faithfully simulate aeration tank performance. Therefore, the focus of this work was to undertake rigorous transient simulations of the hydrodynamics and oxygen mass transfer in a lab-scale aeration tank in order to work towards the development of robust modeling guidelines for activated sludge systems. Unlike most previous CFD analyses of aeration systems, the work reported here employed the shear stress transport (SST) k − ω turbulence model to account for the turbulent interactions between the phases inducing bubble breakup and/or coalescence, and as a consequence, promoting the formation of bubbles of different sizes and shapes. The results obtained were compared with those arising from an analysis using the standard k − ε (sk − ε) model -and assuming fixed bubble diameter-the most common CFD modeling framework used within the wastewater modeling community. Model validation was achieved using acoustic Doppler velocimetry and particle image velocimetry techniques, and experimentally derived oxygen mass transfer data. Limitations of both turbulence models used and modeling assumptions concerning bubbly flow are discussed. The benefits of the SST k − ω turbulence model are demonstrated, but the need to balance the increased computational expense of this approach compared to the sk − ε model and, indeed, bubble flow modeling are recognized. Thus, this paper presents the first rigorous analysis of turbulence model and bubble flow generation models together for activated sludge system optimization.

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Section: Previous Modeling Approachesmentioning

confidence: 99%

Towards a robust CFD model for aeration tanks for sewage treatment – a lab-scale study

Karpinska

Bridgeman

2017

Engineering Applications of Computational Fluid Mechanics

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“…The robustness of OUR monitoring to estimate K L a has been proved in lab reactors in previous studies [27]. Although the OUR can be calculated by the DO profile in the model case [28] or in a pilot plant [29], in practice the DO slope is sensitive to the uneven spatial distribution velocity in the reactor. Therefore, using standard tests to determine in situ OUR was recommended for OTR estimation instead of using DO profiles along the reactor.…”

Section: Process Monitoring Of Our Do Velocity and Shaft Powermentioning

confidence: 97%

Optimal Surface Aeration Control in Full-Scale Oxidation Ditches through Energy Consumption Analysis

Qiu

Zhang

et al. 2018

Water

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Abstract:Oxidation ditches are popularly used in rural areas and decentralized treatment facilities where energy deficiency is of concern. Aeration control technologies are well established for diffusion systems in order to improve energy efficiency, but there are still challenges in their application in oxidation ditches because surface aerators have unique characteristics with respect to oxygen transfer and energy consumption. In this paper, an integral energy model was proposed to include the energy, aeration, and fluidic effects of surface aerators, by which the energy for aeration of each aerator can be estimated using online data. Two types of rotating disks with different diameters (1800 mm and 1400 mm) were monitored in situ to estimate the model parameters. Furthermore, a feedforward-feedback loop control strategy was proposed using the concept of energy analysis and optimization. The simplified control system was implemented in a full-scale Orbal oxidation ditch, achieving an approximately 10% saving in full-process energy consumption. The cost-benefit analysis and carbon emission assessment confirmed the economic feasibility and environmental contribution of the control system. The energy model can help process designers and operators to better understand and optimally control the aeration process in oxidation ditches.

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“…In the study, they were applied for flow field simulations with the momentum source term approach, and the simulation results were compared with the experimental data. Lou et al (2005), Fan et al (2010), andYang et al (2011) adopted the standard k -e turbulence model in MRF and the moving mesh approach to simulate the flow in the ditch; since all gained good results, the standard k -e turbulence model was used in the MRF and SM simulation cases. In the simulation, the free surface of the ditch was treated as a flat, rigid lid, so a slip wall was given to the surface of the oxidation ditch.…”

Section: )mentioning

confidence: 99%

“…Fan et al (2010) simulated the 3D solid-liquid two-phase flow field in a laboratory-scale oxidation ditch aerated with surface aerators using the multiple rotating reference frame approach (MRF) and the standard k -e turbulence model. Yang et al (2011) predicted the flow field in a full-scale Carrousel oxidation ditch with the 3D standard k -e turbulence model and a modified moving mesh approach. In previous study, we have proposed a momentum source term approach, only based on dimensions and the rotational velocity of aerators, to calculate the flow field in a fullscale Carrousel oxidation ditch ( Jiang et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Computational Fluid Dynamics Simulation of Flows in an Oxidation Ditch Driven by a New Surface Aerator

Huang

Wang

et al. 2013

Environmental Engineering Science

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In this article, we present a newly designed inverse umbrella surface aerator, and tested its performance in driving flow of an oxidation ditch. Results show that it has a better performance in driving the oxidation ditch than the original one with higher average velocity and more uniform flow field. We also present a computational fluid dynamics model for predicting the flow field in an oxidation ditch driven by a surface aerator. The improved momentum source term approach to simulate the flow field of the oxidation ditch driven by an inverse umbrella surface aerator was developed and validated through experiments. Four kinds of turbulent models were investigated with the approach, including the standard k -e model, RNG k -e model, realizable k -e model, and Reynolds stress model, and the predicted data were compared with those calculated with the multiple rotating reference frame approach (MRF) and sliding mesh approach (SM). Results of the momentum source term approach are in good agreement with the experimental data, and its prediction accuracy is better than MRF, close to SM. It is also found that the momentum source term approach has lower computational expenses, is simpler to preprocess, and is easier to use.

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Study on two operating conditions of a full-scale oxidation ditch for optimization of energy consumption and effluent quality by using CFD model

Cited by 65 publications

References 17 publications

Towards a robust CFD model for aeration tanks for sewage treatment – a lab-scale study

Towards a robust CFD model for aeration tanks for sewage treatment – a lab-scale study

Optimal Surface Aeration Control in Full-Scale Oxidation Ditches through Energy Consumption Analysis

Computational Fluid Dynamics Simulation of Flows in an Oxidation Ditch Driven by a New Surface Aerator

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