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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 Image Modified
Figure 1: Raw Water and Effluent Turbidity vs Flow Rate Image Modified
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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Additionally, this experiment was done using 3 consecutive ramp states. This was done because a layer of particles forms on top of the foam sheets during the duration of the experiment. The A governing hypothesis for 3 consecutive ramp states allow us to see if the flow rate going through the filter or the layer of film was governing filter performancewas that during the first ramp state, a layer of film was developing and affecting performance and thus performance could not be isolated and could be accounted for either by varying flow rate or the accumulation of a film layer.

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 means suggests that the layer of film on top of the foam sheets is affecting filter performance, and this needs to be considered when designing a filtration unit. 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 find out the importance of the film layer.
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Figure 3: Effluent Turbidity vs. Flow RateAfter it was determined that the film that forms on top of the foam sheets affects performance, it was necessary to test and see if foam filtration is actually a function of depth: Depth Filtration