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The purpose of this experiment was to test pulsing lime into the two apparatuses. Because both apparatuses fail after a shorter time than desired, it was hypothesized that the lime initially added to the apparatus (100 grams) eventually reached a point where it would no longer properly dissolve and raise the pH. Thus, more lime was needed as the experiment progressed. However, adding 100 grams each time would severely overwhelm the system. The following graph was referenced to determine the appropriate amount of lime that needed to be pulsed in every 6 hours:
Figure 1
From this graph one can see that the amount of lime that must be added for a flow rate of 30 mL/min is approximately 2.365 grams and for a flow rate of 40 mL/min, 3.154 grams of lime must be added.
The group determined that it would be best to pump in the stock solution at the highest possible flow rate, which is 380 mL/min. The group determined that pumping in the lime solution at the highest rate possible for only one minute would not create too much of a disturbance in the overall flow rate of the apparatuses. Thus, 380 milliliters of stock solution are pumped in every six hours. One challenge to this set up is that there is only one pump and one concentration for the stock solution. However, each apparatus requires a different mass of lime to be pulsed in, according to Figure 1 above. To solve this problem, the higher concentration of stock solution was made according to the calculations for A2, which resulted in a concentration of 8.3 grams of lime per liter.
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