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The experimental results for gas removal rate using Sand 40 and Sand 30 gave consistent results. This data has been essential in confirming that the apparatus is performing reliably. Yet the results deviate from the theoretical model, which predicts the theoretical bubble formation potential to be around 18mL/L for water that has been previously exposed to 1 atm gage pressure at temperature of 25 C. The model calculates the theoretical bubble formation potential as a function of the air pressure that the water equilibrated with prior to returning to atmospheric pressure. For further analysis, we measured the dissolved oxygen concentration at the effluents from the aerator, sand filter, and bubble collector. The Both the model and DO measurements have been instrumental in pointing at out several improvements with in design of the current apparatus.
Consequently, the following design modifications have been advised to make:
The unexpected results come from measuring dissolved oxygen concentrations at various points in the system. The results indicate that high pressure in the sand filter causing more bubbles to dissolve into the water. Fixing this problem requires some major rethinking of the way the system works, especially in improving aerator efficiency and pressure maintenance in the sand filter. We will replace the large aeration stone in the aerator with four smaller ones to try to improve gas dissolution in the aerator.