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In these experiments, the alum concentration is being was varied to study how a change in alum dose affects the floc blanket formation and effluent turbidity. The experimental set up is the same as the one used in Spring 2009. From these results, the velocity gradient thresholds and effect of organic matter will be investigated with the intent to characterize the system in terms of tube settler efficiency.
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Overall, the system performed well and most of the average effluent turbidities were below 1 NTU. The overdose of alum did cause the effluent turbidity to be slightly higher than the ideal dose, however it was still within the range of ideal effluent turbidity. It was expected that the 35 mg/L alum dose would perform poorly. However, this underdose produced better results than the ideal alum dose, so further experiments are being performed to collect data with a low lower alum dose.