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Plate Settler Spacing research focuses on developing a more thorough understanding and optimizing the lamellar sedimentation process of AguaClara plants. Currently the plants use lamella, which are a network of stacked, sloped plates with narrow channels between them. These are used to provide more surface area for particles to settle out, thereby significantly decreasing the sedimentation tank plan area. As water flows up through these channels, coagulated dirt particles are caught by the plates and fall down into the sedimentation tank. In the lab the Plate Settler Spacing Team (PSS) uses tube settlers to simulate the effects of lamella, where different tube diameters represent different spacing between the plates. The performance of these two technologies are comparable after adjusting for geometric differences, and results from bench-scale experiments can be applied to plate settlers. The team is focusing on a failure mechanism called floc roll-up, where high velocity gradients near the wall (present in small diameter tubes or at close plate spacings) overcome the floc particles' settling velocity causing flocs that would otherwise be captured to roll up into the effluent. Velocity Gradient theory (detailed in the PSS Fall 2010 Velocity Gradients Experiments) dictates that performance deterioration due to floc roll-up will be more significant for tube settlers than for plate settlers, given that the tube diameter equals the plate spacing. This is due to the geometric differences between tubes and plates, so using tube settlers for the bench-scale system represents the worst case scenario for failure.

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