Browsing by Subject "flocculation"
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Item A study of micro fiber dispersion using digital image analysis(Texas A&M University, 2004-11-15) Hendrarsakti, JoonedThe area of the digital image processing is getting more attention in the hope that it will increase the accuracy of any scientific measurements, such as in determining an object velocity, temperature, and size. While human vision is excellent to recognize and differentiate objects, it has been proven to be a poor tool when it comes to measure the object performance. One of many digital image processing applications is texture analysis whose purpose is to evaluate image patterns. The purpose of this dissertation is to investigate the use of texture analysis as a tool to micro fiber dispersion measurement. Micro fiber dispersion can be found in many applications such as in paper and industry powder engineering. Three cases related to micro fiber dispersion were investigated in this study. The first case was the experimental study of the dispersion in open water channel. Sets of synthetic fibers were put into water channel to simulate a process that can be found in papermaking industry. The research investigated the effect of three operating parameters: fluid velocity, fiber consistency, and fiber aspect ratio to fiber dispersion. Using two-factorial experimental design technique, the main and interaction effects of these parameters were evaluated. The study found that increasing fluid velocity, fiber aspect ratio, and consistency decreased the dispersion level. The study also found that the effect of individual parameters is more pronounced than the role of the interactive terms on the fiber flocculation. The second case considered was applying the fiber dispersion analysis to computer-synthesized images consisting of different arrangements of fibers. Four sets of sub-cases were presented. These sub-cases were divided based on the fiber-concentrated location and fiber distribution. The use of computer-synthesized images was found to be very useful to simulate real situation during fiber dispersion. The third case investigated the fiber distribution on a dry paper. Images for different types of paper were taken and evaluated to see the dispersion level of each type of paper. It was found that the current texture analysis was applicable to determine the dispersion level for dry papers. While three cases indicated that the texture analysis can be used to investigate the fiber dispersion, the texture analysis used here is not a perfect and universal method and may not be suitable to analyze other types of dispersions. The human vision will always be essential to determine if the texture analysis is applicable to any other problem.Item Aggregation and transport kinetics of crude oil and sediment in estuarine waters(Texas A&M University, 2004-09-30) Sterling, Michael Conroy, Jr.Modeling the transport and fate of spilled crude oil is important for estimating short and long-term toxicity effects in coastal ecosystems. This research project investigates the partitioning of hydrocarbons from a surface crude oil slick, the resurfacing of chemically dispersed crude oil droplets, the suitability of in-situ field instruments for oil and sediment characterization, and the aggregation and settling of dispersed oil and suspended sediments. An initial laboratory study was conducted to investigate apparent hydrocarbon solubility in petroleum/water systems. Mixing shear and initial crude oil layer thickness were related empirically to oil entrainment rate. A model describing hydrocarbons partitioned in colloidal and soluble phases was consistent with experimental data. A second laboratory study was conducted to investigate the influence of coalescence kinetics on mean droplet size and resurfacing rate of chemically dispersed crude oil droplets. Increased mean shear rates resulted in mean droplet diameters and oil resurfacing rates. A third laboratory study was conducted to compare particle size and fractal dimension measurements obtained using a submersible flow cytometer, an electrozone particle counter, and a light scattering particle sizer. Measured particles included latex beads, crude oil, clay, crude oil-clay aggregates, and crude oil-silica aggregates. Tested instruments gave consistent size measurements for all particle systems, suggesting their suitability for sizing marine particles. To describe the aggregation kinetics of oil-sediment systems, a modified Smoluchowski model based on coalesced sphere (CS) assumptions was developed. Observed collision efficiency values (?OBS) were related to collision efficiency values for single particle type systems (?HOMO) and those for two particle type systems (?HET) using a probabilistic approach. For clay and crude oil, ?HOMO values were higher than the ?HOMO value for silica. Clay-oil and silica-oil have similar ?HET values. Thus, crude oil can significantly increase the aggregation rates of noncohesive sediments such as silica. The CS model above was modified to incorporate sediment fractal geometry. The ability of this modified coalesced fractal sphere (mCFS) model to fit experimental data sets was better than that of a coalesced sphere (CS) model. Because of their reduced settling rates, sediments with lower fractal dimension form more aggregate with dispersed oil.Item Phosphorus reduction in dairy effluent through flocculation and precipitation(Texas A&M University, 2005-02-17) Bragg, Amanda LeannPhosphorus (P) is a pollutant in freshwater systems because it promotes eutrophication. The dairies in the North Bosque and its water body segments import more P than they export. Dairies accumulate P-rich effluent in lagoons and use the wastewater for irrigation. As more P is applied as irrigation than is removed by crops, P accumulates in the soil. During intense rainfall events, P enters the river with stormwater runoff and can become bio-available. Reducing the P applied to the land would limit P build up in the soil and reduce the potential for P pollution. Since wastewater P is associated with suspended solids (SS), the flocculants, poly-DADMAC and PAM, were used to reduce SS. To precipitate soluble P from the effluent, NH4OH was added to raise the pH. Raw effluent was collected from a dairy in Comanche County, TX, and stored in 190-L barrels in a laboratory at Texas A&M University. Flocculant additions reduced effluent P content by as much as 66%. Addition of NH4OH to the flocculated effluent raised the pH from near 8 to near 9, inducing P precipitation, further reducing the P content. The total P reduction for the best combination of treatments was 97%, a decrease from 76 to 2 mg L-1. If this level of reduction were achieved in dairy operations, P pollution from effluent application would gradually disappear.Item The application of eccentric rotating cylinder apparatus for the improved study of particle coagulation(Texas A&M University, 2004-11-15) Lee, Chun WooConcentric rotating cylinder and turbulent mixing devices have been frequently used in studying mixing and particle coagulation. However, these apparatus develop simple laminar flow (concentric rotating cylinders) or do not have well-defined flow (turbulent mixing devices). In this work, the eccentric rotating cylinder apparatus was investigated to find applicability for the improved study of coagulation based on the modified analytical solution of Ballal and Rivlin. Various eccentricity ratios, rotation speeds and viscosities were simulated to obtain optimum operating conditions. Inertial forces working on the fluid increased as the eccentricity ratio and rotation speed increase. As inertial forces increase, the eddy developed in wide clearance was more skewed in the direction of rotation. Both root-mean-square velocity gradient and average principal strain-rate, were increased by increasing eccentricity ratio. avaerage principal strain-rate were linearly increased as rotation speed increases, which suggested that average prinipal strain-rate can properly represent mixing intensity. Comparison of average principal strain-rate and RMS velocity gradient revealed that RMS velocity gradient overestimated mixing intensity and its error increased as eccentricity ratio increases. This study showed that the eccentric rotating cylinder apparatus has a non-uniform velocity distribution with well-defined fluid dynamics. Therefore, the eccentric rotating cylinder apparatus can be applicable as a model flocculator. However, in order to achieve reliable model predictability, the fluid Reynolds number must be below 200.