Dissolved Oxygen Measurements
According to MathCAD modeling of the system, bubble formation potential in the water should be 18 mL/L.In the second experiment we conducted during the summer, which is described here, gas removal was only 2 mL/L. To achievea better understanding of how the system functions, we measured dissolved oxygen concentrations at various points in the system.
Procedure
Sampling Points: Water Source, Aerator Effluent, Sand Filter Effluent, Bubble Collector Effluent
Water Temperature: 20.8 °C for the first probe, 21 °C for second probe
Dissolved oxygen probes were used to measure the concentration of dissolved oxygen in samples of water taken from the water source and effluents from the aerator, the sand filter, and the bubble collector. Two probes were used in samples at each point to confirm results. After each probe was assembled, it was placed in a solution of sodium sulfite to ensure a zero reading. To test the probe's accuracy, it was placed in a sample of tap water, which should have a dissolved oxygen content near 8 mL/L.
In a large beaker, water was collected from a sampling port at the first point, just beyond the water source. The probe was inserted near the center of the water sample and kept stable with a ring stand. After the probe membrane came in equilibrium with the water, the dissolved oxygen reading was recorded, and the probe was returned to the sodium sulfite solution. The beaker was emptied and refilled with water from the next sampling port. This was repeated until water from all four sampling ports had been tested.
Results and Discussion
The results were very surprising. Table 1 shows
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