Experiment 3: Alum Dose = 65 mg/L

An alum dose of 65 mg/L is considered to be a slight overdose.
Figure 1: Effluent Turbidity vs. Time, Floc Blanket on Low, Alum dose = 65 mg/L


Figure 2: Effluent Turbidity vs. Time, Flock Blanket on High, Alum dose = 65 mg/L


Conclusions

For the floc blanket at both the lower and higher levels, the capture velocity of .058 mm/s produces a lower effluent turbidity than the Vc = .116 mm/s, and Vc = .174 produces a higher effluent turbidity than Vc = .116 mm/s, which is expected.  However, Vc = .231 mm/s produces a lower effluent turbidity than Vc = .174 mm/s.  This is not consistent with what should have happened, and cannot be explained by floc particles rolling up the settler tube into the effluent.

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