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This is a significant underdose. These graphs show the effluent turbidity plotted against time for capture velocities of 0.058, 0.116, 0.174, and 0.231 mm/sec.
Figure 1: Effluent Turbidity vs. Time for Floc Blanket on low, alum dose = 15 mg/L
Figure 2: Effluent Turbidity vs. Time for Floc Blanket on high, alum dose = 15 mg/L
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