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This set of experiments attempts to replicate the grain size research performed with the previous experimental setup (link?). Additionally, the effectiveness of each of the components in the setup will be assessed with respect to theoretical expectations. It Theoretically, it is expected that the aerator under 2 atm of pressure will be able to supersaturate the water
General Procedure
with 18 ml/L of dissolved gas. With the current aerator, a major assumption made is that the dissolved gas concentration equilibrates with the pressure in the aerator, sending water with 18 ml/L of dissolved gas through the sand filter.
General Procedure
The procedure for each experiment in this set is fairly similar, with the exception of sand grain sizes, which are varied among the experiments. For the two experiments listed below, the same procedure was used with varying sand grain sizes. Sand 40 (0.49 mm - 0.57 mm) and Sand 30 (0.59 mm - 0.84 mm) were used for experiments one and two, respectively. (Is the procedure the same but you are varying sand grain size or did you make modifications between the two methods? If so, please note the modifications you made, if not avoid vague language such as fairly similiar and state what conditions you changed and if you did not, state that you utilized the same procedure)
(Are you referring now to how to run an experiment? Perhaps create this as a link to another page as guidance) In Process Controller, configure the system so that the aerator air pressure is maintained at roughly 100 kPa. Fill the sand column with 60 cm of Sand 40 and adjust the flow rate on the pump forcing water through the sand filter to establish a bed expansion of 50%. For the first experiment, manual measurements of flow rate were performed by unhooking the influent water tube into the sand filter and allowing the influent to fill a large graduated cylinder over the course of a minute. In order to minimize changes made to the system, flow rate measurements for the second experiment were taken at the system effluent tube. The flow rates were roughly 225 ml/min and 485 ml/min for Sand 40 and Sand 30, respectively.
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The water entering the aerator and leaving is maintained at a constant rate throughout the experiment via manually controlled pumps. The water is allowed to flow through the sand column, where bubbles can form. When bubbles grow large enough in the filter, they can float up to the top and out through a tube into the bubble collector. Throughout the duration of the experiment, the bubble collector goes through cycles of unfilling emptying and refilling. Initially, an air valve at the top of the bubble collector opens and the water effluent valve located at the bottom of the bubble collector closes, allowing the collector to fill like a sitting column of water. Once a maximum height is reached, the air valve shuts off and the water valve opens, resulting in a partial vacuum at the top of the collector. This suspends the column of water in the bubble collector. As bubbles enter the collector, gas in the bubbles fills the partial vacuum, allowing the water column to slowly drain from the collector. Once the minimum water level in the collector is reached, the apparatus refills and the cycle begins again.
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