Experimental and numerical analysis of the hydrodynamic behaviors of aerobic granules

Liu, Li; Sheng, Guo‐Ping; Li, Wen‐Wei; Zeng, Raymond J.; Yu, Han‐Qing

doi:10.1002/aic.12476

Cited by 8 publications

(3 citation statements)

References 31 publications

(27 reference statements)

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“…Li and Logan employed a fractal scaling concept and proposed a clustercluster structure to model aggregate permeability [12]. Recently, the computational fluid dynamic method has been used to determine internal flow through particle aggregates [13][14][15]. However, most of these model predications have not been experimentally validated.…”

Section: Introductionmentioning

confidence: 99%

Investigation and visualization of internal flow through particle aggregates and microbial flocs using particle image velocimetry

Xiao

Lam

2013

Journal of Colloid and Interface Science

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An advanced particle-tracking and flow-visualization technology, particle image velocimetry (PIV), was utilized to investigate the hydrodynamic properties of large aggregates in water. The laser-based PIV system was used together with a settling column to capture the streamlines around two types of aggregates: latex particle aggregates and activated sludge (AS) flocs. Both types of the aggregates were highly porous and fractal with fractal dimensions of 2.13±0.31 for the latex particle aggregates (1210-2144 μm) and 1.78±0.24 for the AS flocs (1265-3737 μm). The results show that PIV is a powerful flow visualization technique capable of determining flow field details at the micrometer scale around and through settling aggregates and flocs. The PIV streamlines provided direct experimental proof of internal flow through the aggregate interiors. According to the PIV images, fluid collection efficiency ranged from 0.052 to 0.174 for the latex particle aggregates and from 0.008 to 0.126 for AS flocs. AS flocs are apparently less permeable than the particle aggregates, probably due to the extracellular polymeric substances (EPSs) produced by bacteria clogging the pores within the flocs. The internal permeation of fractal aggregates and bio-flocs would enhance flocculation between particles and material transport into the aggregates.

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Section: Introductionmentioning

confidence: 99%

Investigation and visualization of internal flow through particle aggregates and microbial flocs using particle image velocimetry

Xiao

Lam

2013

Journal of Colloid and Interface Science

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“…Therefore, the model is more accurate than the Wen-Yu model in predicting the interaction between anaerobic granular sludge and sewage. Therefore, the drag force model of granule swarms can be described as Equations (8)- (10) and (13). In this study, two ultimate values are considered in Equation (13).…”

Section: Drag Force Coefficient Of Anaerobic Granule Swarmsmentioning

confidence: 99%

“…A new equation for mean drag force on particles was developed and better prediction results were achieved. In Liu's work [10], the hydrodynamic behaviors of granules were studied by experimental and CFD methods. The results showed internal flow for granules is significantly dependent on permeability and Reynolds number.…”

Section: Introductionmentioning

confidence: 99%

CFD Simulation on Hydrodynamic Behaviors of Anaerobic Granule Swarms

2019

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An internal circulation (IC) anaerobic reactor is widely used in the treatment of municipal and industrial wastewater with high volumetric loading rates. The performance of an IC reactor is closely related with hydrodynamic behaviors of anaerobic granules. Typically, anaerobic granules work in swarms and the settling behavior of a granule is disturbed by other granules. However, the research on anaerobic granule swarms is insufficient. In this work, Computational Fluid Dynamics (CFD) method was employed to study the hydrodynamic behaviors of anaerobic granule swarms with various voidages. The simulated results showed that the average velocity inside granules increased significantly as the voidage of granule swarm decreased and as the Reynolds number increased. The maximum shear stress on the granule’s surface increased with decreasing voidage and increasing Reynolds number. Based on the hydrodynamic behaviors of anaerobic granule swarms, an improved model of drag force coefficient for granule swarms was developed. The predicted expanded height, using the improved model, gives better consistency with experimental results. The improved model can embed in CFD code to improve the precision of the description of the IC reactor model and provide valuable information for designing and operating an IC reactor.

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PDA measurements in a three‐phase bubble column

Gan

Law

2013

AIChE Journal

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Phase Doppler anemometry was used to quantify the flow characteristic of a three phases (liquid, solid, and bubbles) cylindrical bubble column driven by a point air source made of a 30‐mm diameter perforated air stone centrally mounted at the bottom. The cylindrical bubble column had an inner diameter of 152 mm and was filled with liquid up to 1 m above the point source. Acrylic beads with a nominal diameter of 3 mm were used as the solid phase. To match the density of the solid phase which was 1.05 kg/m3, the liquid density was raised to about 1.0485 kg/m3 by added salt. The bubble diameters generated were within the range of 600–2400 µm. The detailed turbulent characteristics of the liquid‐phase velocity, bubble diameter, bubble velocity, and solid velocity were measured at three different air rates, namely 0.4, 0.8, and 1.2 L/min (corresponding to average gas volume fraction of 0.0084, 0.0168, and 0.0258, respectively) for the homogeneous bubble column regime. With the addition of the solid phase, the flow field was found to be relatively steady compared to the two‐phase column referencing the probability density functions for both the liquid and bubble velocities. An analysis based on the determination of the drag forces and transversal lift forces was performed to examine the flow stability in the three‐phase bubble column. The analysis illustrated that how the added solid phase effectively stabilized the flow field to achieve a steady circulation in the bubble column and a generalized criterion for the flow stability in the three‐phase bubble column was derived. Further investigation for the transition and the heterogeneous bubble column regime with air rates at 2.0 and 4.0 L/min shown that this criterion can also be used as a general prediction of flow stability in this three‐phase bubble column. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2286–2307, 2013

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Experimental and numerical analysis of the hydrodynamic behaviors of aerobic granules

Cited by 8 publications

References 31 publications

Investigation and visualization of internal flow through particle aggregates and microbial flocs using particle image velocimetry

Investigation and visualization of internal flow through particle aggregates and microbial flocs using particle image velocimetry

CFD Simulation on Hydrodynamic Behaviors of Anaerobic Granule Swarms

PDA measurements in a three‐phase bubble column

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