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Wastewater sedimentation modeling

The sedimentation of organic solids in a rectangular primary clarifier tank was modeled in this case study. Wastewater flows continuously from the inlet to the outlet of the sedimentation tank. As observed in the contour plot of velocity magnitude and velocity vector shown in the figure below, the bottom of the sedimentation tank is almost in a quasi-steady state condition and recirculation flow with very low-velocity magnitude.

Sedimentation of the particles happens along the length of the tank, depending on the particle sizes. Larger particles settle quickly near the tank inlet, smaller particles settle slowly at or near the outlet wall of the reactor, while fine particles are non-settable and leave the settling tank via the tank's outlet.

Velocity magnitude contour plot

Velocity vector showing  recirculation flow inside settling tank

Particle size distribution in a sedimentation tank

Virtual real-time visualization of settling velocity and settling particle size distribution along the length (from inlet to outlet) of the settling tank 

Multiphase flow model of the aeration process

Efficient transfer of oxygen and carbon dioxide removal is essential for microorganisms' growth and enhances the process performance in wastewater treatment plants and fermentation reactors. This study focused on understanding oxygen transport and distribution in a 3m deep rectangular reactor injecting oxygen at the bottom of the reactor using equally spaced diffusers.

 The computed result below shows the reactor's hydrodynamics using velocity contour and vector plot. The velocity vector plot indicates the existence of recirculation flow in the reactor. The real-time animation of oxygen volume fraction distribution shows how oxygen distribution is affected as recirculation develops in the reactor. The model gives a great visualization of oxygen distribution, design limitation, and optimization requirements to distribute oxygen uniformly, avoiding/reducing recirculation flow.

Real-time animation of oxygen distribution in a liquid 

Liquid velocity vector 

Liquid velocity contour

Combined liquid velocity vector and  contour - Zoomed

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