h1. Floating Flocs
h2. Overview
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[!floating floc.jpg|width=250px!|Dissolved Air Flotation of Flocs]
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Floating flocs in the sedimentation tanks of AguaClara plants in Tamara, Ojojona, and Marcala result in polluted effluent water. While some treatment plants use floating floc to treat water, AguaClara plants rely on flocs settling out at the bottom. The cause of the problem is thought to be bubbles forming on floc particles due to supersaturation of influent water. Water is supersaturated with gas when the total dissolved gas pressure is greater than the local solution pressure. The goal of the Floating Floc team is to find an efficient and cost-effective approach to remove excess gas from water and to implement that method in current and future AguaClara plants to improve the sedimentation process.
Currently, the Floating Floc team is conducting research with a back-washed sand filter to remove excess gas from the water in the grit chamber before it reaches the sedimentation tank. Placing sand in the water would provide a surface area other than the floc particles on which bubbles can form to leave the water. The goal is to remove enough excess gas, so that the water entering the sedimentation tank has a lower bubble forming potential. The research being performed specifically focuses on observing and quantifying the effectiveness of different sand grain sizes at different bed expansionsexpansions of the sand bed. Data collected so far indicates that smaller grain sizes increase the effectiveness of gas removal from the water. However, with smaller sand grain sizes a floating sand problem occurs. Similar to the floc situation, smaller sands are more likely to be carried away by the bubbles, which may result in significant sand loss over time.
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[!sludgeTop.jpg|width=250px!|Dissolved Air Flotation of Flocs]
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AguaClara plants rely on a sedimentation process to treat water. In many plants, gas bubbles forming on floc and lifting them to the surface result in polluted effluent water. Gas bubbles form in water when the total dissolved gas pressure is greater than the local solution pressure, or rather when the water is supersaturated with gas. The goal of the Floating Floc team is to find an efficient and cost-effective approach to remove excess gas from water and to implement that method in current and future AguaClara plants to improve the sedimentation process.
Research is currently being performed with a back-washed sand filter column. The sand provides an alternate surface on which gas bubbles can form and leave the solution. We postulate that the main factors affecting gas removal via sand filtration are sand size and amount, flow rate, and bed expansion. Our main objective is to find the optimal parameters to maximize gas removal and minimize the amount of sand carried away by bubbles. The results of our research may result in adjustments to the grit chamber dimensions of AguaClara plants.
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[!sludgeTop.jpg|width=250px!|Dissolved Air Flotation of Flocs]
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Floating Floc Team [Semester Goals|Floating Floc Goals]
Floating Floc Team [Meeting Minutes|Floating Floc Meeting Minutes]
h2. Current Research
[Floating Floc Sand Filter Method|Floating Floc Sand Filter Method]
* The sand filter approach involves forcing water upward through a layer of sand, as if backwashing a sand filter. The sand filter method provides a substance besides the sediment in the water on which the bubbles can form. When the bubbles grow large enough, they will rapidly rise to the surface.
h2. Additional Information
[Floating Floc Aeration Method|Floating Floc Aeration Method]
* This page discusses past research on the aeration approach to dissolved oxygen removal. The aeration approach attempted to use bubbles as a catalyst to increase the rate of dissolved oxygen transfer out of solution by allowing dissolved oxygen to diffuse into the bubbles. This would increase the bubble size and cause the bubble to rise faster.
[Theoretical Modeling of Aeration Method|Floating Floc Research]
* This page discusses the research into the floating floc phenomenon that is being conducted.
Floating Floc Team [Annotated Bibliography|Floating Floc Annotated Bibliography]
[Quiz|Floating Floc Quiz]
This quiz checks that you have a basic understanding of the principles behind this research. | 