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Replicability:
Every experiment was replicated to test the reliability of the results given by FReTA. The results were quite good for the 5 NTU water as you can see on figure ? A and B. For experiments at 100 and 500 NTU, looking at residual turbidity don't really seem accurate, figure ? and ?. This could be explained by the fact that alum clogged the connector where alum and water are mixing and this problem was found later. However, we felt confident using the data since the experiments and their replicate were really close on the mean sedimentation velocities graphs.
A
B
Figure ?: Plot of the residual turbidity as a function of alum dose for an effluent water of 5 NTU and it's replicate A: For a flocculator 2787 cm long. B: For a flocculator 8388 cm long.
Figure ?: Plot of the residual turbidity as a function of alum dose for an effluent water of 100 NTU and it's replicate for a flocculator 5592 cm long
Figure ?: Plot of the residual turbidity as a function of alum dose for an effluent water of 500 NTU and it's replicate for a flocculator 2787 cm long
Mean sedimentation velocities :
The data processor retrieves mean sedimentation velocities of the particles at each alum dose during an experiment from our data. Since the mean sedimentation velocities are calculated when we fit the data, the mean sedimentation velocities given for a 5 NTU influent water are not accurate. Indeed, even if the data processor tries to fit the data, the shape of the evolution of turbidity as a function of sedimentation velocity does not look like the fit function.