Towards improved accuracy in modeling aeration efficiency through understanding bubble size distribution dynamics

Amaral, Andreia Neves do; Bellandi, Giacomo; Rehman, Usman; Neves, Ramiro; Amerlinck, Youri

doi:10.1016/j.watres.2017.10.062

Cited by 38 publications

(25 citation statements)

References 33 publications

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“…%C data for both the aerated (dark green) and unaerated (light green) is shown. The impact of viscosity on aeration has been previously reported for fine bubble aerators with reference to both the constriction of the air bubble stream (Fabiyi and Novak, 2008) and bubble coalescence (Amaral et al, 2018) at increased viscosities. However, there appears to have been no previous reports of impacts on coarse bubble aerators and the consequences regarding non-uniform air-scouring of membranes.…”

Section: Studies At High Mlss Formentioning

confidence: 93%

Clogging vs. fouling in immersed membrane bioreactors

et al. 2018

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Whilst the fouling of MBR membrane surfaces has been very extensively explored by the academic community, there is an increasingly widespread recognition by practitioners of the issue of clogging of membrane channels with sludge solids, sometimes termed "sludging". The study undertaken has quantified this phenomenon using a bespoke test cell allowing a flat sheet membrane channel to be viewed directly during operation and the accumulated solids determined by digital image processing. Sludging behaviour has then been correlated both with the sludge properties, from sludge samples taken from both an industrial and municipal MBR, and the permeability decline rate data. The work has revealed the expected trends in fouling propensity, as quantified by the exponent n of the Δp/Δt = m.exp(nJ) correlation from classical flux-step tests. With zero membrane aeration the industrial samples exhibited sludging, the filling of the complete thickness of the membrane channel with sludge solids, whereas for municipal sludge the solids formed a cake layer which did not fill the channel. In the absence of sludging the permeability decline followed the expected pattern of increasing at the elevated soluble COD and capillary suction time values of the industrial sludge, compared with municipal sludge at the same solids concentration range (8-12 g.L). However, there was no evident correlation between fouling (permeability decline without sludging) and sludging: incipient sludging did not appear to influence permeability, though can be assumed to negatively impact on long-term operation, or relate to the sCOD concentration. Sludging instead appeared to depend on the sludge physical properties, and primarily the viscosity: sludge samples at high viscosities were found to exhibit a different air-scour pattern to that at normal MLSS concentrations. Outcomes suggest that sludging is caused by rheological conditions promoting bubble coalescence and bubble stream constriction, reducing the exposure of the membrane surface to scouring air.

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Section: Studies At High Mlss Formentioning

confidence: 93%

Clogging vs. fouling in immersed membrane bioreactors

et al. 2018

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“…The fact that the residence time of bubbles in the water affected the oxygen mass transfer may be related to the time needed for the oxygen mass transfer, which needs further research. In addition, some scholars have mentioned that the local dynamic characteristics of K L a [27] may be related to the characteristic parameters of bubble movement at each spatial position, and the functional relationship between K L a and each spatial position should be established. Thus, the author can see the deficiency of the research from this literature, that is, the research on oxygen-mass-transfer experiment and bubble-movement parameters should study the average value and the dynamics of K L a.…”

Section: Influence Of Aeration On Characteristic Parameters Of Bubble Plumementioning

confidence: 99%

“…The oxygen mass transfer of microporous hose aeration is affected by many factors, such as pore diameter, aeration gas volume, and depth at which aeration occurs [18,19]. Other factors affecting oxygen mass transfer are flow pattern, shear stress, size of bubbles and their size distribution, and operational conditions [20,21], as well as bubble collisions and coalescence events as bubbles rise, and their velocity [22][23][24][25][26][27]. Nevertheless, most studies focus on external parameters such as aeration parameters and aeration mode, and the influence of bubble movement of microporous aeration on oxygen mass transfer is rarely studied.…”

mentioning

confidence: 99%

Influence of Aeration Rates on Oxygen Mass Transfer and Flow- Field in a Microporous Aeration System

Lü¹,

Cheng²,

Li³

et al. 2021

Pol. J. Environ. Stud.

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Eutrophication waters are becoming a serious problem in many parts of the world. Several technologies such as sludge dredging [1], chemical coagulation [2], bioremediation [3], the addition of mulch [4][5], and artificial aeration [6] have been developed to control and mitigate eutrophication. Among them, artificial aeration is extensively used because of its advantages of simple operation, low cost, and quick effect.At present, the main artificial-aeration technologies are mechanical aeration, water-lifting aeration, and

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“…Many experimental studies (inter alia: Amaral et al, 2018; Darmana et al, 2007; Krishna & Ellenberger, 1996; Pjontek et al, 2014; Rzehak et al, 2017) and numerical analyses (Chen, Sanyal, & Duduković, 2005; Deen et al, 2001; Liang et al, 2016; Rzehak et al, 2017; Yang et al, 2017) have been conducted to understand and improve the performance of bubble columns by making efficient use of the limited volume available (Jakobsen et al, 2005). These studies focused on the influence of several parameters such as column dimensions, gas sparger type and position, the properties of liquid phase, gas superficial velocity, water composition, and operating temperature and pressure.…”

Section: Introductionmentioning

confidence: 99%

“…In the present work, multiphase CFD simulations of air flow in a bubble column operating at low gas flow rates (2 and 8 L·min −1 ) are conducted utilizing OpenFOAM® while using a 2D planar approximation of the system. Experimental data from Amaral et al (2018) are used for validation and evaluation of the examined models. The PBM CM is adopted in the CFD simulations to capture the evolution of the BSD in the bubble column.…”

Section: Introductionmentioning

confidence: 99%

Effects of flow velocity and bubble size distribution on oxygen mass transfer in bubble column reactors—A critical evaluation of the computational fluid dynamics‐population balance model

Khalil

Rosso

DeGroot

2021

Water Environment Research

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Computational fluid dynamics (CFD) is used to simulate a bubble column reactor operating in the bubbly (homogenous) regime. The Euler–Euler two‐fluid model, integrated with the population balance model (PBM), is adopted to compute the flow and bubble size distribution (BSD). The CFD‐PBM model is validated against published experimental data for BSD, global gas holdup, and oxygen mass transfer coefficient. The sensitivity of the model with respect to the specification of boundary conditions and the bubble coalescence/breakup models is assessed. The coalescence model of Prince and Blanch (1990) provides the best results, whereas the output is shown to be insensitive to the breakup model. The CFD‐PBM study demonstrates the importance of considering the BSD in order to correctly model mass transfer. Results show that the constant bubble size assumption results in a large error in the oxygen mass transfer coefficient, while giving acceptable results for gas holdup. Practitioner points Constant bubble size (CBS) and population balance model (PBM) are compared for a bubble column reactor. Both PBM and CBS can predict gas holdup; however, PBM can correctly predict gas–liquid mass transfer whereas CBS cannot. Best practices for selecting coalescence, breakup, and drag models are determined.

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Towards improved accuracy in modeling aeration efficiency through understanding bubble size distribution dynamics

Cited by 38 publications

References 33 publications

Clogging vs. fouling in immersed membrane bioreactors

Clogging vs. fouling in immersed membrane bioreactors

Influence of Aeration Rates on Oxygen Mass Transfer and Flow- Field in a Microporous Aeration System

Effects of flow velocity and bubble size distribution on oxygen mass transfer in bubble column reactors—A critical evaluation of the computational fluid dynamics‐population balance model

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