...
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 pipethe LFOM"
-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
...
Next, we used various-sized pipes inserted within the LFOM to test the "pipe within a pipethe LFOM" 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)
...