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This is an overdose. The graph below shows the effluent turbidity plotted against time for capture velocities of 0.058, 0.116, 0.174, and 0.231 mm/sec, for the low floc blanket level only.
Figure 1: Effluent Turbidity vs. Time for Floc Blanket on low, alum dose = 105 mg/L
Conclusions
This dosage showed poor floc blanket performance, which was the goal of this experiment. However, given that this is an extreme overdose, the resulting effluent turbidity is not as high as expectedextremely high dose was tested to show what a failure looks like (the turbidity is greater than 1 NTU). The effluent turbidity is much higher than one, meaning this is a good demonstration of failure.