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EXPERIMENTAL DIRECTION
This summer , the plate settler team will first focus on the geometry of the tube settlers in order to gain insight into how parameters like the tubes' diameters and lengths affect the effluent turbidity, our main output and target of optimization. After the optimal geometry of the settlers has been determined under ideal conditions at two floc blanket levels, we need to test how robust this geometry actually is. To do so, we will create non-ideal circumstances by varying the influent turbidity and possibly the alum dosing in order to analyze how the system responds. Further, we hope to be able to characterize the system in terms of the fluid's residence time in the tube settlers in order to make correlations to the effluent turbidity.
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The tube residence time is not known to be an important parameter. I suggest keeping the focus on the capture velocity and on the effects of the velocity gradient at the tube walls. |
In past experimentation velocity gradients within the tube settlers have been of much importance. Consequently, we are also interested in developing a physical model of our system that will allow us to explain such phenomena as floc roll-up, wherein velocity gradient thresholds are exceeded and floc enters the effluent water.
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work on generating a controlled ideal experiment as a basis for understanding the robustness of the plate settling system. We plan to test how the settlers function under a wide variance of conditions, since changes in alum dosage and influent turbidity inevitably affect the sedimentation process in many ways. Keeping in mind that the presence of things like natural organic matter in our raw water disturbs floc blanket behavior at a molecular level, we hope to gain some physical insight into how the settling system responds to these fluctuations.
Velocity gradients within the tube settlers have proven to be very important, and we hope to continue past investigation into the nature of their formation, profiles, and physical consequences relative to our system. Since it is likely that the density of our floc particles strongly depends on variable external parameters (like alum dosage and influent turbidity), our direction is highly geared towards a fluid dynamics anlysis
Velocity gradients are likely very important and it is possible that the length of the entrance region where the parabolic velocity profile of laminar flow is setup is also important. The Reynolds number influences the length of the entrance region where the velocity gradient at the tube walls will be higher.
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