Page History

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This semester, I am continuing research as part of the Sedimentation Tank Hydraulics Team. I will be conducting experiments and collecting quantitative data to evaluate the design requirements for floc blanket formation and maintenance. The goals for the semester are:

• Test a hypothesis that describes the conditions required for floc blanket formation. The hypothesis is that the hydrodynamic pressure of the jet must exceed the hydrostatic pressure of the debris flow in order for flocs to be resuspended.
• Determine the maximum upflow velocity in the sedimentation tank that will reliably give a performance of 2-3 NTU.
• Evaluate the effect of high jet velocities on floc breakup and effluent performance.
• Develop an understanding of how floc consolidation works, and determine design guidelines for the floc hopper.

Summer 2011 Contributions

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As part of the Sedimentation Tank Hydraulics Team, I determined that the minimum angle of repose required for floc blanket formation to be about 25 degrees. The minimum angle of repose is the minimum angle of the sloping sides of the sedimentation tank that allow settling flocs to be returned to the jet. Angles smaller than the angle of repose resulted in sludge accumulation, while angles larger than the angle of repose would result in a taller and more expensive sedimentation tank, but also quicker floc return to the jet.