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Figure 1 shows both the raw water turbidity and the effluent turbidity as a function of the flow rate. The effluent turbidity increases with the flow rate. This shows that filter performance decreases with increasing flow rates, meaning that in order to achieve a desirable effluent turbidity, a lower flow rate and thus a larger filter tank size must be employed. As show in the graph, filtration velocities of less than about 2 mm/s produce an effluent turbidity of less than one, or a pC* of greater than 0.9. The graph in figure 1 appears to be a linear function. This can be explained by the idea that at lower flow rates, the foam is able to capture even the smallest particles, since they have been made sticky from contact with alum. However, as the flow rate increases, it become increasingly difficult to capture smaller particles as they are more difficult for the foam to hold on to. When the flow rate increases, it likely pushes these smaller particles right through the filter, resulting in increased turbidity. Figure 1 shows that as the flow rate increases, the minimum trapped particle size likely increases as well. 
Figure 1: Raw Water and Effluent Turbidity vs Flow Rate 
Figure 2: pC* vs Flow RateWhile the results obtained using this alum dose were phenomenal, this is a very high, unrealistic alum dose. To actually achieve this alum dose level, it would be necessary to install an additional alum doser prior to the filtration unit.
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Figure 3 shows the three ramp states as a function of flow rate. The first ramp state has a significantly higher turbidity than the following two. This suggests that this film may have an effect on the performance of the filter. In order to prove or disprove this, experiments will be run with the filter column on its side so this film is unable to perform, and by comparing these results, we will reveal the importance of the film layer. Also, it is important to note that with this lower alum dose, not as many of the smaller particles are being made "larger" or "sticker" from contact with alum, since there is less alum to come in contact with. Therefore, the minimum turbidity achieved with a low alum dose is not as low as the minimum turbidity achieved with the high alum dose. This factor makes the turbidity levels achieved seem constant, versus the linear function achieved in Figure 1. However, Figure 1 and Figure 3 are actually showing similar results, with the exception that the higher alum dose is able to trap smaller particles at lower flow rates since more will come in contact with the alum. This can not be done with the lower alum dose, so the results appear to be more constant with flow rate.
Figure 3: Effluent Turbidity vs. Flow Rate
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