Experimental Method for Retrofit Designs

Once our team figured out the cause of the foam forming in AguaClara plants in operation in Honduras (put link citing causes), we set about designing retrofits for these plants. Our team came up with four different designs to test:
-the "pipe within a pipe"
-the vertical/inclined plane
-the "teacup" theory, using an overflowing bucket to catch the falling water
-a variation on the teacup theory, using a bucket with an orifice in the bottom

See the retrofit designs page for visuals of each theory.

Our first goal was to narrow down from 4 different designs to our top choice to facilitate and expedite lab testing.

Calculations

As a team, we worked in MathCAD to calculate the distance that the jets of water coming into the LFOM would travel inside the LFOM. If we discover that a bucket inserted into the LFOM below the orifices can catch the jets before they hit the water, the bucket theory will be a viable option. We determined that all but the top three jets of water would in fact hit the far wall of the LFOM before reaching any size bucket that we could place in the LFOM. This eliminated both the teacup theory and the variation on that theory as possible solutions. The MathCAD file is attached. (what was the purpose of doing this?)

After eliminating both bucket theories, we decided that testing the last two designs in a lab would not be difficult and would give more realistic, tangible results than our calculations.

Testing and Results

We used the pilot plant to test our retrofit design in an environment that replicated the actual plants as closely as possible. The first design we tested was the vertical/inclined plane. We used a 5cm-wide, 60cm-long steel plate to test the effectiveness of this plan to reduce water aeration. Unfortunately, we determined visually that there was very little, if any, change in the amount of bubbles formed before and after inserting the steel plate into the LFOM. Even at various angles of inclination, the amount of bubbles formed was the same. (can you show any visual confirmation of this with pictures for both or either case?)

Next, we used various-sized pipes inserted within the LFOM to test the "pipe within a pipe" theory. First, we tested a 3cm-diameter pipe by inserting it vertically into the 7.5cm-inner diameter LFOM. There was no noticeable change in the amount of bubbles formed under the LFOM. Second, we tested a 5cm pipe. This produced a drastic reduction in the amount of bubbles formed under the LFOM. After leaving the 5cm pipe in the LFOM for 5 minutes, we decided there would be no overflow problem. Finally, we tested a 6cm pipe for 5 minutes in the LFOM. We noticed that the water level outside the LFOM rose slowly throughout the 5 minutes until the water flowed over the top of the LFOM. This clearly meant that the 6cm pipe was too big. (attach mathcad sheet here)

We were able to document results for each variation of the designs visually with photographs and short movies on cameras.