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Data analysis was performed in a similar way as was performed in the Experiment 1. Figure 1. depicts the initial and final water level in the bubble collector during each of the data collection period ("runs"). Each run represents a specific time period during which the water level in bubble collector gradually sinks down from its maximum to the set minimum point. This period is represented on the graph when the line slants downward. Once the minimum water level is reached, the system has to refill with water in order to continue the runs. For this reason, the water outflow valve is closed until the water level reaches the set maximum point. This period is represented on the graph by the vertical lines. As opposed to the Experiment 1, during this experiment the runs were governed by the duration of the flush valve. The flush valve was installed prior to the experiment with the purpose of removing any air entrained in the lines before it entered the sand filter.
More detailed information on the bubble collector setup can be found here.
The initial data collection period was omitted from the analysis since because of the setup conditions the air might have been trapped inside the system. For the subsequent data collection periods, we calculated the content of gas removed per liter of water sent through the sand filter. We added fitted a line to each of the runs to see the rate of change of the water level inside the bubble collector when water runs through the sand filter. Figure 2. and Figure 3. show the linear fit line for the second data collection period, and more detailed graphs can also can be found here.
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