*** This version of Confluence is for testing only and contains a copy of content from June 29th 2026. No changes will be preserved. ***
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Ideas for full scale implementation that we will be investigating at Laboratory Scale:
• Add air bubbles using suction through a small hole in the side of a down-flowing pipe right before the water enters the grit chamber. The additional air in the water will increase the bubble size as it joins the preexisting air pockets. The pressure in the pipe could also be maintained at a partial vacuum to accelerate the bubble formation process.
• Add sand to the bottom of the grit chamber simulating back-wash in a sand filter. The idea is that the dissolved oxygen in the water will form bubbles on the sand particles. Once the buoyant force is greater than the connection between the bubble and the sand particle, it will rise to the surface of the water.
• Add the equivalent of lamellas to the grit chamber. Bubbles will form on the underside of the lamella and eventually become large enough that they roll across the lamella surface and float to the surface of the water.
Two contraptions will be made that we will use to simulate different situations to help us determine the best course of action. The team will also be split into two subgroups so that each experiment can have the undivided attention of different team members. The members of each subgroup were decided based on class and work schedules. Tiffany and Tanya will be working on the aeration experiments and Haley and Ling will be focusing on the backwash sand filter. Wenny will be assisting each team interpret the data, contemplating other experiments that can be performed, attending meeting and assisting on written assignments.
MODEL 1: AERATION
Aerator ApparatusLink to diagram
The first will consist of a dissolved oxygen probe and a pressure sensor connected to a 4 inch PVC pipe with a suction outlet, a hole for influent water, an air stone and an air inlet line. To drain the system, the water inlet line can be detached over the sink at a valve that can be toggled shut near the source of the water. A partial vacuum can be maintained by pumping the air out of the cylinder via the suction outlet. The device also has a stir bar inside to help us model a complete mix system. As we adjust the pressure in the cylinder, the pressure sensor will allow us to know that the actual pressure is in the pipe. The DO probe will allow us to track the rate at which the oxygen leaves the water. The level of DO needed to keep the flocs from rising to the top of the sedimentation tank in the treatment plants has yet to be determined.
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The length of each test run will be determined once we have the experimental device working. We currently do not know how the data will behave the kinetics of the bubble formation and thus we do not know how long each test run should the batch tests in the pressure/vacuum chaber will need to be. The data will be evaluated based on the level of dissolved oxygen in the water and how big the bubbles are. The goal is to determine the pressure and air flow rate that produce the biggest bubbles and lowest DO level. This should help us determine the optimum orifice size and its height above the outlet of the pipe.
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Our experimental set-up consists of a 63 cm glass column with a an inner diameter of 3 2.5 cm, with caps for each end that allow water inflow and outflow. We will fill the tube partially with sand and use a pump to send super-saturated tap water through the tube in a continuous flow (tapwater pressure should be sufficient). The flow will be large enough to suspend the sand particles, as though backwashing a sand filter. Water and any air bubbles that form will flow out of the tube at the top to a collection container open to the atmosphere, where will place the DO probe. The DO probe will monitor the dissolved oxygen content of the out-flowing water to help us determine the effect of the sand filter on dissolved oxygen levels.
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