Sedimentation efficiency of two continuously operating circular settling tanks with different inlet- and outlet arrangements

Bajcar, Tom; Steinman, Franci; Širok, Brane; Prešeren, Tanja

doi:10.1016/j.cej.2011.10.054

Cited by 21 publications

(12 citation statements)

References 14 publications

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“…The secondary settling tank (SST) is widely employed in the separation of solid and liquid phases in activated sludge processes treating domestic and industrial wastewater, such separation occurs by gravitational sedimentation (Ekama et al 1997). There are many important factors that directly affect the design of SST, such as local climatic conditions, variations in plant operating conditions, sedimentation velocity, geometric tank configurations and wastewater characteristics, such as density and viscosity (Clercq 2003;Bajcar et al 2011;Patziger 2016;Ramin et al2014).…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional simulation of a secondary circular settling tank: flow pattern and sedimentation process

Almeida

Rezende

Mataczinski

et al. 2020

Braz. J. Chem. Eng.

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A secondary circular settling tank (SCST) with low hydraulic load was numerically analyzed. A transient, three-dimensional model was employed to evaluate flow in a pilot plant. Three phases were considered: clean water was a continuous phase; sludge was a dispersed phase and an air layer under atmospheric conditions was considered above the surface of the water at the top of the tank. Height and diameter of the baffle located in the tank inlet was studied in order to reduce the resuspension of sludge particles. High velocity magnitude and turbulent kinetic energy cause resuspension of solids in the center of the bottom of the tank. With the sludge outlet closed, after 30 min of simulation there was an increase of approximately 1.0% in sludge concentration. The results provided detailed insight into the hydrodynamic flow within the SCST. Keywords Secondary circular settling tank • Computational fluid dynamics • Multiphase flow • Wastewater treatment Abbreviations C D Drag coefficient H Tank height (m) Interfacial force p Pressure (Pa) r Volume fraction for the α-phase t Time (s) t q Particle drop time (s) U Velocity vector v t Terminal velocity of the particle (m/s) Greek letters Turbulence dissipation rate (m 2 /s 3) k Turbulent kinetic energy (m 2 /s 2) Dynamic viscosity (kg/(m s)) t Turbulent viscosity Density (kg/m 3) Turbulent frequency (1/s) Subscripts Indicates the phase in the flow

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Section: Introductionmentioning

confidence: 99%

Three-dimensional simulation of a secondary circular settling tank: flow pattern and sedimentation process

Almeida

Rezende

Mataczinski

et al. 2020

Braz. J. Chem. Eng.

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show abstract

“…In the same context, some studies have been done on the optimization of inlet design and position in order to avoid dead zones formation. Bajcar et al [10] proved that vertical flow in circular settling tank is more efficient than horizontal flow in terms of removal efficiency, especially at high inlet suspension concentration. Rostami et al [11] simulated the flow field in rectangular clarifier with different inlet apertures and showed that increasing number of slots improve uniformity of the flow and decrease the size of circulation zone.…”

Section: Introductionmentioning

confidence: 99%

Improving removal efficiency of sedimentation tanks using different inlet and outlet position

Bouisfi¹,

Bouisfi²,

Ouarriche³

et al. 2019

FME Transactions

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Sedimentation by gravity is the oldest water treatment. Inlet and outlet of rectangular sedimentation tank are often located in the middle of the tank. The present investigation studies the effect of changing inlet and outlet position of rectangular sedimentation tank on removal efficiency using Computational Fluid Dynamics method. Two different configurations are proposed and they have been tested with varying particles diameters and concentration. Numerical model ability to describe flow field behaviour inside the tank is confirmed by an experimentation data. Results show that inlet and outlet position influence the flow field and removal efficiency of sedimentation tanks, especially for the case of fine particles (50 and 120µm).

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“…Note that in this form with the right side set to 0, the equation is identical to the one of the optical flow as proposed by Horn and Schunck [6]. Derivatives are discretized using the central difference method:…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…Furthermore, visualization methods are also preferred for multiphase flow analysis, especially in biological and chemical engineering, where other methods are too intrusive or do not allow measurements on the micro scale. For example, Bajcar et al [5] and [6] used visualization techniques to study sedimentation efficiency in circular settling tanks.…”

Section: Introductionmentioning

confidence: 99%

Flow Image Velocimetry Method Based on Advection-Diffusion Equation

Bizjan

Orbanić

Širok

et al. 2014

SV-JME

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Sedimentation efficiency of two continuously operating circular settling tanks with different inlet- and outlet arrangements

Cited by 21 publications

References 14 publications

Three-dimensional simulation of a secondary circular settling tank: flow pattern and sedimentation process

Three-dimensional simulation of a secondary circular settling tank: flow pattern and sedimentation process

Improving removal efficiency of sedimentation tanks using different inlet and outlet position

Flow Image Velocimetry Method Based on Advection-Diffusion Equation

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