Influence of Natural Organic Matter on Colloid Transport and Attenuation in Saturated Porous Media-experimentation and Modelling PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Influence of Natural Organic Matter on Colloid Transport and Attenuation in Saturated Porous Media-experimentation and Modelling PDF full book. Access full book title Influence of Natural Organic Matter on Colloid Transport and Attenuation in Saturated Porous Media-experimentation and Modelling by Xinyao Yang. Download full books in PDF and EPUB format.
Author: Xinyao Yang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
Author: Xinyao Yang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
Author: Xinyao Yang
Publisher: LAP Lambert Academic Publishing
ISBN: 9783847377405
Category : Attenuation (Physics)
Languages : en
Pages : 244
Get Book Here
Book Description
Colloids refer to particles or macromolecules with at least one dimension of 1nm 1m. A wide range of environmental particles fall within this category including microorganisms, nanoparticles, and mineral precipitates. Understanding colloid fate and transport in porous medium not only permits more effective protection of water supplies, but also allows for the development of more effective pollutant remediation strategies. Organic matter (OM) complicates colloid behaviour. To date the influence of OM on colloid mobility in porous media has been largely qualitative. This book presents research leading to the development of multiple-pulse column techniques that may be integrated with mathematical models to quantify the effects of OM on particulate colloid attenuation in saturated porous medium. Research has investigated how two groups of environmental organic compounds, humic acids and proteins, influence particulate colloid attenuation by saturated sand. Study findings may shed light on complex colloidal behaviour in organic matter impacted environment and be useful to professionals in contaminant hydrogeology, environmental remediation, and wastewater treatment.
Author: Fritz H. Frimmel
Publisher: Springer Science & Business Media
ISBN: 3540713395
Category : Science
Languages : en
Pages : 294
Get Book Here
Book Description
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.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 5
Get Book Here
Book Description
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.
Author: Yuhong Zhou
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Although extensive research has been conducted to understand the effects of dissolved organic matter (DOM) on fine particle transport, less attention has been paid to NOM in the transport medium (i.e., immobile rock and sediment grains). The objective of this study is to the roles of NOM in the transport medium in mediating particle transport. We conducted an experimental and modelling study on the transport of nanoscale titanium dioxide (nTiO2) and illite colloid in columns packed with quartz sand under water-saturated conditions. Peat moss was used as an example NOM and packed in some of the columns to investigate its influence on particle transport. Experimental results showed that NOM may either increase or decrease particle transport depending on the specific conditions. NOM in the transport medium was found to attract particles and reduce particle mobility when the energy barrier between particle and NOM is low or non-existent. NOM also adsorbed to Fe and Al oxyhydroxides and promoted the transport of negatively-charged particles at low pH. Partial dissolution of NOM releases DOM, and the DOM adsorbs to and increases the transport of positively-charged particles. Additionally, NOM changes pore water pH, which influences particle mobility by affecting the interaction energy between the particle and transport medium. Modelling results showed that the deposition sites of peat moss are very heterogeneous, and the NOM from peat moss may reduce particle deposition rate by adsorbing to the particle and/or transport medium. Findings from this study demonstrates that NOM in the transport medium not only changes properties of the medium, but also may alter water chemistry. Therefore, the role of NOM in mediating particle transport is complicated and dependent on the properties of the particle, NOM, and mineralogical composition of the medium.
Author:
Publisher:
ISBN:
Category : Colloids
Languages : en
Pages : 40
Get Book Here
Book Description
Author: Ann Mathew
Publisher:
ISBN:
Category :
Languages : en
Pages : 272
Get Book Here
Book Description
Author: Peter Grathwohl
Publisher: Springer Science & Business Media
ISBN: 146155683X
Category : Science
Languages : en
Pages : 198
Get Book Here
Book Description
Diffusion in Natural Porous Media: Contaminant Transport, Sorption/Desorption and Dissolution Kinetics introduces the general principles of diffusion in the subsurface environment and discusses the implications for the fate and transport of contaminants in soils and groundwater. Emphasis is placed on sorption/desorption and the dissolution kinetics of organic contaminants, both of which are limited by the slow speed of molecular diffusion. Diffusion in Natural Porous Media: Contaminant Transport, Sorption/Desorption and Dissolution Kinetics compiles methods for calculating the diffusion coefficients of organic compounds (in aqueous solution or vapor phase) in natural porous media. The author uses analytical solutions of Fick's 2nd law and some simple numerical models to model diffusive transport under various initial and boundary conditions. A number of these models may be solved using spreadsheets. The book examines sorption/desorption rates of organic compounds in various soils and aquifer materials, and also examines the dissolution kinetics of nonaqueous phase liquids in aquifers, in both the trapped residual phase and in pools. Diffusion in Natural Porous Media: Contaminant Transport, Sorption/Desorption and Dissolution Kinetics concludes with a discussion of the impact of slow diffusion processes on soil and groundwater decontamination and the implications of these processes for groundwater risk assessment.
Author: Hongjuan Bai
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
The investigation of the transport and retention of bacteria in porous media has a great practical importance in environmental applications, such as protection of the surface and groundwater supplies from contamination, risk assessment from microorganisms in groundwater, and soil bioremediation. The aim of this study is to gain a fundamental understanding of the mechanisms that control bacteria transport and deposition in saturated and unsaturated porous media. Laboratory tracer and bacteria transport experiments at Darcy scale were performed in three porous media with distinct pore size distribution in order to investigate and quantify water and bacteria transport process under steady state flow conditions. A conservative solute was used as water tracer to characterize water flow pathways through porous media. A gram negative, motile Escherichia coli, a gram negative, non-motile Klebsiella sp. and a gram positive, non-motile R. rhodochrous were selected for the transport experiments. Characterization of cell properties (such as cell size and shape, zeta potential, motility and hydrophobicity) was performed for each strain. Numerical simulations with HYDRUS-1D code were performed to characterize water flow and to estimate bacteria transport and deposition parameters. The later were explored to identify bacteria flow patterns and physicochemical or physical mechanisms involved in bacteria deposition. To provide a better understanding of the mechanisms involved on bacteria transport and deposition, pore scale experiments were carried out by using microfluidic devices, designed for this purpose. The information obtained from laboratory experiments and numerical modeling was improved by theoretical calculation of different interactions between bacteria and porous media at air/water/solid interfaces. DLVO and non-DLVO interactions such as hydrophobic, steric, capillary and hydrodynamic forces involved in bacteria deposition were considered to describe bacteria-interface interactions in order to identify their relative impact on physicochemical and physical deposition of bacteria. Results obtained through both laboratory experiments and numerical simulationsoutlined non-uniform flow pathways, which were dependent on both grain/pore size as well as pore size distribution of the porous media. For a given porous medium, water flow patterns became more non-uniform and dispersive with decreasing water saturation due to the presence of air phase, which lead to an increase of the tortuosity of the flow pathways under unsaturated conditions. Bacteria transport pathways were different from the tracer transport, due to size exclusion of bacteria from smaller pore spaces and bacteria motility. Bacteria deposition was greatly influenced by pore network geometry, cell properties and water saturation degree. Both physical straining and physicochemical attachment should be taken into account to well describe bacteria deposition, but their importance on bacteria deposition is closely linked to porous media and cell properties. The results obtained in this work highlighted the simultaneous role of cell properties, pore size distribution and hydrodynamics of the porous media on bacteria transport and deposition mechanisms. The calculation of DLVO and non-DLVO interactions showed that bacteria deposition in saturated and unsaturated porous media was influenced by both kinds of interactions.
Author:
Publisher:
ISBN:
Category : Medicine
Languages : en
Pages : 2036
Get Book Here
Book Description
Vols. for 1963- include as pt. 2 of the Jan. issue: Medical subject headings.
