h1. Plate Settler Spacing
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h4. Introduction
This research is focused on a deepermore thorough understanding of the sedimentation process so that AguaClara plants canmay remove flocsflocculated particles from cleantheir effluent waterstreams as efficiently as possible,. allowing for successful chlorination of the effluent water. Currently, AguaClaraCurrently the plants use lamella in their clarification systems, which are a network of slopedstacked, stackedsloped plates that createwith narrow channels throughbetween them. which clarifiedAs water can flow.
To emulate lamellar sedimentation, we use tube settlers of various diameters, which simulate the effects of the lamellar plates.
A majority of flocs that enter these inclined channels settle out due to the force of gravity, significantly reducing effluent turbidity, which is a measure of how clear water is, to increase the effectiveness of chlorination. There is no control of influent water parameters going to the plant, so there is a keenflows through these channels gravity pulls out coagulated dirt particles, resulting in a clean effluent. In the lab the Plate Settler Spacing Team uses tube settlers to simulate the effects of lamella, where different tube diameters represent different spacing between the plates. The properties of these two technologies are analogous and our results from the lab are directly applicable to plate settlers.
Since we are unable to control the turbidity level of the influent water entering the AguaClara plants, there is a significant interest in developing a settlingrobust system that is robust \-after floc blanket clarification that will produce less than 1 NTU water. The standard of 1 NTU exceeds the standards of 5 NTU for the WHO, butwith high performance over a wide range of influent conditions. Nephelometric Turbidity Units, or NTU, are a measure of how concentrated a dirty solution is based upon how much that solution scatters light. In the lab we aim to produce clean water with less than 1 NTU turbidity—and though this surpasses the WHO's 5 NTU demarcation, it does not meet the standard ofEPA's 0.2-0.3 NTU for the EPA. The EPA standard is very requirement, which is difficult to meetachieve without a filtration step, which is not a part of the AguaClara design.
Ultimately, we hope .
We strive to optimize the lamella design in order to achieve effluent water with a turbidity of 1 NTU or less \-\-turbidity, even under water chemistry fluctuations and variations in alum dose variation. At present the dosage. Some of the fundamental parameters which control the design of our experiments are plate spacing, capture velocity, and velocity gradientthe formation are three of ourvelocity keygradients designbetween limitingthe constraintsplates.
h4. VelocityCurrent GradientTeam Research Focus: Velocity Gradients
Past research has brought to light illuminated the importance of flow regime characteristics on the importanceperformance of tube settlers. Specifically, when velocity gradients withinestablished in the tube settlers. Flocs become too large, flocs at the bottom wall of the tube that experience an upward velocityforce pull greater than the force of gravity pulling them down willand out of the effluent stream. This causes flocs to roll up the side of the wall and exit with the effluentclean water, dramatically affecting the final turbidity. Flocs Since flocs are fractal particles whose effective diameters are sensitive to shear stress, natural organic material in the water, and influent turbidity, so determining their response to the velocity gradient may require more than just is a simplecomplex forceproblem balance.that Furthermore,goes the maximum velocity gradient achieved at steady state will fluctuate with a plant's influent conditions and flow rate through their lamellabeyond a force balance.
[Subteam Semester Goals and Future Challenges|Plate Settler Spacing Goals]
[Weekly Subteam Progress|Plate Settler Spacing Meeting Minutes].
[Research Plan|Plate Settler Spacing Research Plan]
h2. Experimental Methods and Results
h3. Fall 2009
h5. [Experiments with Saturated Water Influent|PSS Fall 2009 Experiments with Saturated Water]
This section contains the experiment run in collaboration with the Floating Floc team to test the effect of saturated water in the influent on the plate settler performance
h5. [Experiments with the Velocity Gradient|PSS Experiments with the Velocity Gradient]
This section contains the model derived to estimate floc roll up in relation to particle size and velocity. Also, experiments were run to collect data to support the model
h5. [Experiments with Natural Organic Matter|PSS Fall 2009 Experiments with Natural Organic Matter]
This section contains experiments testing the effect of natural organic matter (humic acid) on the plate settler performance
h3. [Previous Semester Research|PSS Summer 2008 to Fall 2009]
h2. Additional Information
[Annotated Bibliography of Relevant Literature|PSS Bibliograhpy]
[Processor Controller Information|PSS Process Controller and Data Analysis]
[PSS Quiz for New Members |PSS Quiz]
[Fall 2008 Photo Gallery|Photo Gallery]
[PSS Apparatus Design] | 