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The apparatus worked well with the established upflow velocity. It was possible to observe the movement of particles. At the top of the apparatus, water looked clear but according with the pH sensor, it was saturated with base. A great amount of lime was captured on the middle of the apparatus; probably, the upflow velocity didn't allow the particles to reach the bottom of the apparatus again. However it is a desirable behavior because the lime was still in the apparatus, giving the protons needed by water.
The pH remained stable in 12 units just for 20 minutes. It was necessary to calibrate again the pH probe, to clean the apparatus and to review the calculations in order to determine the reason of the pH behavior. After the reviewing, the team decided to increase the amount of lime, because it was seen that not all the lime was on suspension.
Figure 1. pH vs time
CONCLUSIONS
• It was necessary to run one experiment recalculating the amount of lime.
• The design seems as expected and the movement of the particles was desirable. However, there was a cluster of particles that remains at the bottom and didn't dissolve.