Download or read book Dynamics of Colloid Transport and Deposition in Heterogeneous Granular Porous Media written by Chun-Han Ko and published by . This book was released on 1999 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling of Colloid Transport and Deposition Dynamics in Porous Media written by Jeffrey Y. Chen and published by . This book was released on 1998 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamics of Colloid Deposition in Granular Porous Media written by Menachem Elimelech and published by . This book was released on 1998 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Colloid Mobilization and Transport in Contaminant Plumes written by and published by . This book was released on 1999 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling Deposition Dynamics and Transport of Colloidal Particles in Heterogeneously charged Porous Media written by Philip Randolph Johnson and published by . This book was released on 1995 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Colloidal Transport in Porous Media written by Fritz H. Frimmel and published by Springer Science & Business Media. This book was released on 2007-05-26 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the basics of abiotic colloid characterization, of biocolloids and biofilms, the resulting transport phenomena and their engineering aspects. The contributors comprise an international group of leading specialists devoted to colloidal sciences. The contributions include theoretical considerations, results from model experiments, and field studies. The information provided here will benefit students and scientists interested in the analytical, chemical, microbiological, geological and hydrological aspects of material transport in aquatic systems and soils.
Download or read book Influences of Flow Transients and Porous Medium Heterogeneity on Colloid Associated Contaminants Transport in the Vadose Zone written by and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past year (June 2003 to June 2004), work at Yale has centered on investigating the influences of porewater pH, flow transients, and the presence of natural organic matter (NOM) on the deposition and mobilization of clay colloids (kaolinite and illite) within columns packed with unsaturated porous media. The experiments on pH and flow-transient effects were described in our First-Term Progress Report (which covered the initial 18 months of the study) and will not be repeated here. More recent experiments on the role of NOM in colloid transport proved equally as interesting. Even at porewater concentrations as low as 0.2 mg/L, soil-humic acid substantially lowered clay-colloid deposition rates compared to the case in which soil-humic acid was absent from the porewater. We attribute this to adsorption of the humic acid to the positively charged edge sites of the clay colloids, which effectively reduced the colloid affinity for negatively charged air- and solid-water interfaces. Comparison of the results of the column experiments to calculations of a new mathematical model has sharpened our inferences regarding mechanisms that govern the rate-limited deposition and mobilization of colloids. We are testing these inferences by carrying out flow-and-transport visualization experiments. We have constructed a semi-transparent representation of a porous medium, consisting of a rectangular parallel-plate chamber that encloses 3-5 layers of uniformly sized sand grains. Ceramic plates fused to the ends of the chamber maintain the capillary tension and syringe pumps (located at the inlet and outlet ends) regulate the flow of water and colloids through the partially saturated sand. By placing the chamber beneath a microscope, we can examine the distribution of colloids between air-water and solid-water interfaces, directly measure the kinetics of deposition onto these interfaces, and observe the mechanisms that contribute to the release of immobile colloids. To date, we have used fluorescent microspheres as the colloids, but, once we refine our methodology, we intend to use clay particles as the colloids.
Download or read book Influences of Flow Transients and Porous Medium Heterogeneity on Colloid Associated Contaminant Transport in the Vadose Zone written by Joseph Ryan and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: We are investigating the role of colloids in the movement of radionuclides through water unsaturated porous media. This research is guided by a key objective of the Environmental Management Science Program (EMSP), which is to improve conceptual and predictive models for contaminant movement in complex vadose zone environments. In the report entitled National Roadmap for Vadose Zone Science and Technology [DOE, 2001], increases in the understanding of colloid-contaminant interactions, colloid mobilization, and colloid deposition within unsaturated soils are cited as requisite needs for predicting contaminant fate and distribution in the vadose zone. We seek to address these needs by pursuing three overarching goals: (1) identify the mechanisms that govern colloid mobilization, transport, and deposition within unsaturated porous media; (2) quantify the role of colloids in scavenging and facilitating the transport of radionuclides; and (3) develop and test a mathematical model suitable for simulating the movement of colloid associated radionuclides through variably saturated porous media.
Download or read book Colloid Transport in Saturated Porous Media written by Ann Mathew and published by . This book was released on 2007 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2000 with total page 992 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantitative Multi spectral Light transmission Imaging of Colloid Transport in Porous Media at the Meso Scale written by Erika Lorna Kraft and published by . This book was released on 2011 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: Colloids, particles smaller than ten microns in diameter, are ubiquitous in the subsurface. Colloids have an effect on the transport of contaminants that bind to their surfaces, and can reduce the permeability of aquifer materials through deposition. Some microorganisms, including pathogens, are also transported in the subsurface as colloids. The study of colloid transport behavior is important to the improvement of contaminant transport predictions, and thus to the protection of water quality. Imaging technologies provide detailed spatial-temporal concentration data not obtainable by traditional methods, which rely on the collection and analysis of water samples at discrete locations. A quantitative, light-transmission imaging system was developed for the observation of solute and colloid transport in a chamber containing porous media. Multi-spectral LEDs and high-quality optical filters were used with a sensitive charge-coupled device camera to obtain images of a 47x57cm sand pack containing two fluorescent tracers--disodium fluorescein and red-fluorescent latex colloids. The properties of the optical components, and the selection of tracers, were optimized to allow for collection of data on three distinct properties of the system in time and space--water content, fluorescein concentration, and colloid concentration. An image processing technique was developed to normalize collected images and to remove noise. The system was calibrated through comparison of processed intensities with known fluorescein and colloid concentrations. Quantification was possible over the concentration range 10-2 to 102ppm for fluorescein, and 10-1 to 103ppm for colloids. This wide range of detection and the very low detection limits were made possible by the improvement in the signal-to-noise ratio that resulted from system development. Experiments were conducted to demonstrate the utility of this method to observe and quantify fluorescein and colloid transport. Model predictions compared favorably with collected data over multiple data sets, each containing approximately 300 data points. Colloid transport was reasonably fit by the advection-dispersion equation using a retardation factor and a first-order deposition coefficient to represent colloid interactions with the sand surface. In some cases, accurate description of colloid transport will require a more detailed parameterization of colloid dynamics that was beyond the scope of this work. Data presented in this thesis however demonstrate the power of this system to provide insight into the fate and transport of fluorescein and colloids in porous media. These insights facilitate prevention of groundwater pollution by colloidal contaminants, and contribute to effective design of remediation strategies for colloid-contaminated environments.
Download or read book Colloid Transport in Physically and Geochemically Heterogeneous Porous Media written by Ning Sun and published by . This book was released on 1998 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Manipulation of Groundwater Colloids for Environmental Restoration written by John McCarthy and published by CRC Press. This book was released on 1993-01-04 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: This valuable resource discusses several strategies of manipulating colloids for environmental restoration, identifies advantages and disadvantages of each strategy, and considers obstacles limiting the application of each strategy. Approaches evaluated include the following: Chemical modification of subsurface systems to mobilize or deposit colloids in situ Altering the mobility of microorganisms to improve delivery of microbes for bioremediation Manipulating colloids or biocolloids (bacteria) to change aquifer permeability to either enhance bioremediation or create in situ barriers Introducing modified colloids, surfactants, and emulsions to control colloid mobility or to increase recovery of sorbed contaminants by pump and treat methods Manipulation of Groundwater Colloids for Environmental Restoration also contains short, focused research reports on specific studies relevant to the various approaches under consideration. Subjects covered range from mobility of organic macromolecules by controlled field injection experiments to new techniques that investigate surface chemistry and aggregation of inorganic colloids. Other topics discussed include the depositional behavior and transport of biocolloids in porous media, surfactants as modifiers of surface binding sites on colloids, and genetic engineering of microorganisms to serve as contaminant-scavenging biocolloids. Manipulation of Groundwater Colloids for Environmental Restoration is an excellent resource for research scientists in hydrology, chemistry, and microbiology; environmental consultants; regulators; environmental engineers; bioremediation microbiologists; and engineers.
Download or read book Three dimensional Pore scale Visualization and Trajectory Analysis of Colloid Transport and Retention in Saturated Porous Media written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The research contained in this thesis investigates the transport and deposition behavior of 1.1 and 3ìm carboxylate-modified microspheres in saturated porous media under unfavorable deposition conditions. Colloid motion and deposition patterns are visualized in three dimensions using a high-speed confocal microscope and micromodels packed with glass beads or sand grains. This study specifically focuses on colloid behavior in the grain-to-grain contact region, which has been suggested in previous studies as an important location for colloid retention under unfavorable conditions. The use of the high resolution confocal microscope allowed the distinction of two types of colloidal retention that can occur in the grain-to-grain contact region and showed that single surface retention was much more abundant than retention on two surfaces (straining). This study also demonstrated that both the extent and rate of straining are enhanced by increasing flow rate. In addition to obtaining qualitative descriptions of colloid deposition patterns, this study is the first to provide quantitative analysis of the motion of individual colloidal particles leading to the construction of three-dimensional colloid trajectory in both the bulk phase and grain-to-grain contact regions. The results demonstrated the dominant effects of hydrodynamics on colloid motions, i.e., most colloids entering the grain-to-grain contact region tend to follow the streamlines to detour the contact point, making straining a transport-limited process. Retention in the secondary energy minimum can significantly retard colloid movement but this association was not strong enough to keep the retained colloid inside the energy well over time. Colloid retention and movement through sand-packed sand micromodels were more complex compared to those packed with glass beads due to the more complex hydrodynamic conditions resulting from the irregular packing geometry and surface roughness of sand. These results suggest that theoretical torque analysis based on the idealized scenarios is not a suitable approach for describing colloid transport and deposition under unfavorable conditions in complex natural porous media.
Download or read book Exploring Colloid Transport in Unsaturated Porous Media Using X Ray Microtomography written by Chris L. Brueck and published by . This book was released on 2016 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the mechanisms controlling colloid transport and deposition in the vadose zone is an important step in protecting our water resources. Colloid transport in unsaturated porous media was studied using X-Ray Microtomography (XMT), which is a non-destructive imaging technique that provides three-dimensional images at a resolution on the order of 3 [micro]m/pixel. Under favorable attachment conditions, 5 -15 [micro]m hydrophobic silver coated hollow glass spheres were suspended and drained through sintered glass bead columns at flow rates of 0.5, 5.0 and 50.0 mL/hr. The results show that total colloid deposition was dependent on drainage flow rate and saturation. A positive correlation was found between the total colloid concentration and the number of trapped air bubbles. An image processing algorithm was written to assess the partitioning of colloids to the solid-water interfaces (SWIs), air-water interfaces (AWIs), and air-water-solid (AWS) contact lines, which led to the conclusion that at medium to high water contents, AWIs and AWS contact lines were equally important for colloid attachment and mobilization. Lastly, colloids were shown to be left behind the main drainage front, becoming immobilized in the disconnected wetting phase by attachment to SWIs, or in pendular wetting phase rings.
Download or read book Colloid Deposition and Aggregation in the Presence of Charged Collectors written by Behnam Sadri and published by . This book was released on 2015 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Colloidal-collector interactions are of fundamental importance in separation and filtration technologies. Here, the effect of collector grains on the behavior of colloidal particles was studied in two different experimental systems, i.e., column studies with stationary collectors and batch mixing to study hetero aggregation. Polystyrene latex beads, 100 nm diameter, and soda lime glass beads, with two different diameters of 212-300 $\mu$m and 710-1180 $\mu$m, were employed as colloidal particles and collector grains, respectively. Column experiments were performed to understand fate of colloidal particles in the porous medium. There are three major phenomena that control colloidal transport in porous media: Deposition, aggregation, and straining. These three distinct types of particle dynamics in porous media were studied by adjusting physicochemical properties of colloidal suspension. Furthermore, the effect of washing the collector beads was studied. Batch experiments, in which known amount of collector grains are added to colloidal suspension with known concentration, are designed to investigate more collector-colloids interaction role in transport dynamics of colloidal particles. UV-Vis spectroscopy and dynamic light scattering techniques are employed to understand both deposition and aggregation of colloidal particles in the vicinity of collector grains. Results obtained by dynamic light scattering revealed that aggregation is the predominant factor in this colloidal system. The possible sources for this type of behavior are also tackled by undertaking controlled experiments. In the batch experiments, ions leaching from the surface of glass beads, effect of mixing, and glass beads presence are confirmed as the three major reasons behind the aggregation of colloidal particles.
Download or read book Morphology of Shear induced Colloidal Aggregates in Porous Media written by Alejandro Javier Perez and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Colloid deposition in granular media is relevant to numerous environmental problems. Classic filtration models assume a homogeneous pore space and largely ignore colloid aggregation. However, substantial evidence exists on the ubiquity of aggregation within porous media, suggesting that deposition is enhanced by it. This work studies the deposition process in relation to aggregate size and structure. We demonstrate that aggregation is induced at typical groundwater velocities by comparing the repulsive DLVO force between particle pairs to the hydrodynamic shear force opposing it. Column experiments imaged with high-resolution X-ray Computed Tomography were used to measure aggregate structure and describe their morphology probability distribution and spatial distribution. Aggregate volume and surface area were found to be power-law distributed, while Feret diameter was exponentially distributed with some flow rate dependencies caused by erosion and restructuring by the fluid shear. Furthermore, size and shape of aggregates are heterogeneous in depth, where a small number of large aggregates control the concentration vs depth profile shape. The range of aggregate fractal dimensions found (2.2-2.42) implies a high potential for restructuring and/or breaking during transport. Shear induced aggregation is not currently considered in macroscopic models for particle filtration, yet is critical to consider in the processes that control deposition.
