In situ characterization of local hydrodynamic parameters in closed-loop aeration tanks

Fayolle, Yannick; Gillot, S.; Cockx, Arnaud; Bensimhon, Laetitia; Roustan, M.; Héduit, A.

doi:10.1016/j.cej.2009.12.043

Cited by 27 publications

(12 citation statements)

References 10 publications

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“…Moreover, it is interesting to observe that the k L a decline follows the degradation kinetics of organic matter, expressed as COD, which corroborate the obtained results. The k L a values obtained in these assays are in the same range that of values achieved by other authors in full-scale aeration tank equipped with fine bubble diffusers and jet loop reactor (Fakeeha et al, 1999;Fayolle et al, 2010). In addition, the respirometric activity of microorganisms which are actively growing in the bioreactor can also be measured based on this dynamic method.…”

Section: Fig 21 Evolution On Ph and Do Concentration In The Ambbsupporting

confidence: 62%

A Methodological Proposal For Corporate Carbon Footprint And Its Application To A Wine-producing Company In Galicia, Spain

2015

Toward a Sustainable Wine Industry

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Section: Fig 21 Evolution On Ph and Do Concentration In The Ambbsupporting

confidence: 62%

A Methodological Proposal For Corporate Carbon Footprint And Its Application To A Wine-producing Company In Galicia, Spain

2015

Toward a Sustainable Wine Industry

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“…In conventional wastewater treatment plants (WWTPs) the aeration of the bioreactors is one of the largest energy consumers (Fayolle et al, 2010). In order to optimize oxygen supply, new control systems have recently been proposed, including those based on the continuous monitoring of nitrogen forms (NH 4 + ,.…”

Section: Introductionmentioning

confidence: 99%

Impact of Aeration Control on N<SUB>2</SUB>O Emission in a Full-Scale Activated Sludge Wastewater Treatment Plant

Filali¹,

Fayolle²,

Peu³

et al. 2013

proc water environ fed

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This work investigated the impact of aeration control strategy on energy consumption and nitrous oxide (N 2 O) emission in a full-scale wastewater treatment plant. Two identical activated sludge processes treating the same effluent but operated with different aeration control strategies were compared. Aeration tank 1 was operated with a new control strategy favouring the simultaneous nitrification denitrification (SND) whereas aeration tank 2 was operated with a conventional control strategy with distinct nitrification and denitrification phases. Results indicated that whereas the N 2 O emission factor was comparable in both systems (in the order of magnitude of 0.004% of the influent TKN load), N 2 O emission pattern was dependent on the adopted aeration control strategy. It has been observed that high aeration flow rates (aeration tank 2) were likely to promote N 2 O transfer from the gas phase to the liquid phase.

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“…The results from the simulations based on the fixed bubble size show that the gas holdup and oxygen transfer in closed-loop AS tanks depend on the axial velocity of the fluid imparted by the mixers. Moreover, accurate prediction of the overall mass transfer coefficient, k L a, relies on correct estimation of the initial bubble size at the diffuser level, requiring either in situ bubble diameter measurements (Fayolle et al, 2010) or implementation of an add-on model to estimate inlet bubble size. Similarly, the need for bubble diameter calibration has been emphasized in more recent CFD work by Terashima, So, Goel, and Yasui (2016), involving use of the same modeling approach to determine k L a values in a number of full-scale activated sludge systems and clean water tanks that differed in their dimensions, diffuser types (coarse and fine-pore, ceramic, plastic and membrane diffusers), their configuration (single and dual spiral roll) and operating airflow rates.…”

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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In situ characterization of local hydrodynamic parameters in closed-loop aeration tanks

Cited by 27 publications

References 10 publications

A Methodological Proposal For Corporate Carbon Footprint And Its Application To A Wine-producing Company In Galicia, Spain

A Methodological Proposal For Corporate Carbon Footprint And Its Application To A Wine-producing Company In Galicia, Spain

Impact of Aeration Control on N<SUB>2</SUB>O Emission in a Full-Scale Activated Sludge Wastewater Treatment Plant

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

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