Initial Experiments
Procedure
Unknown macro: {float}
These are the results of the first several experiments run, with the initial experimental setup. This setup consisted of the flow accumulator and vertical glass filter column. A dissolved oxygen (DO) probe in the flow accumulator recorded the dissolved oxygen concentration of the inflowing tap water. The flow rate and temperature of the water was monitored by a pressure sensor and temperature probe inside the flow accumulator and controlled by valves on the hot and cold water lines. These valves were opened and shut by the program ProcessController. Once the water had run through the filter column, it was collected in a small beaker containing another DO probe, which recorded the dissolved oxygen concentration of the outflowing water.
Results
The first experimental run used glass beads as the filter media and a flow rate of 200 mL/min. The unsuspended filter depth was 32 cm, and the temperature was held at a constant 20 degrees Celsius. Figure 2, below, illustrates the change in dissolved oxygen that occurred over time. The yellow line represents the DO concentration of the inflowing tap water, and the blue line represents the DO of the outflowing water.
Figure 2: The first run, using glass beads, flow rate of 200 ml/min, and filter depth of 32 cm
While the inflow DO concentration was about 9mg/L, the outflow was roughly 11 mg/L. Overall, Figure 2 shows that the outflow DO concentration was higher than the inflow concentration. This was inconsistent with what we predicted. Though it was possible that this setup would have no effect on the the DO of the water, the DO should not be able to increase inside the system. We found that this was most likely due to the error in the DO probes, which we found were not functioning properly.
Conclusion
We concluded that we needed to purchase a new, more reliable DO probe to measure the oxygen concentration, or else we needed to find another method to measure the DO concentration. This led to the development of the [second phase] of our experimental setup.