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Approximately 120 hours later (5 days later), the stock solution was refilled with the same concentration (41.5 g/L). However, the blender had been repaired at this time and was used to prepare the slurry, instead of the mixer. At the same point in time (5 days from the beginning of the experiment) the flow rate for the peristaltic pump flowing to the 5 cm tube settler was increased from 40 mL/min to 50 mL/min in an attempt to raise the pH. The team suspects that when the flow rate in the 5 cm tube settler apparatus is too low, the lime particles settle and create preferential flow paths which keeps the lime from interacting with the water.
Below in figures 1, 2 and 3 Below is the preliminary data from the experiment:
. The 2.5 cm plate settler was relatively stable, achieving a pH of over 12 for well over a week! The 5 cm plate settler, however, never reached a pH of 12 but rather oscillated around a value of approximately 11.5. As time went on, the amplitude of the data's wave increased and the pH started regularly dipping below 10.
Figure 1 - Experiment 9
The above graph is : data from hours 0 to 40 of an experiment pulsing in 41.5 g/L of lime slurry at 380 mL/min for 1 minute every six hours.
Figure 2 - Experiment 9: data from
The above graph is hours 40 to 80
of an experiment pulsing in 41.5 g/L of lime slurry at 380 mL/min for 1 minute every six hours.
Figure 3 - Experiment 9 : data from
The above graph is hours 80 to 120 of an experiment pulsing in 41.5 g/L of lime slurry at 380 mL/min for 1 minute every six hours.