16 research outputs found
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Theoretical and experimental investigations of ferrofluids for guiding and detecting liquids in the subsurface. FY 1997 annual report
Ferrofluids are stable colloidal suspensions of magnetic particles in various carrier liquids with high saturation magnetizations, which can be manipulated in virtually any fashion, defying gravitational or viscous forces in response to external magnetic fields. In this report, the authors review the results of their investigation of the potential of ferrofluids (1) to accurately and effectively guide reactants (for in-situ treatment) or barrier liquids (low-viscosity permeation grouts) to contaminated target zones in the subsurface using electromagnetic forces, and (2) to trace the movement and position of liquids injected in the subsurface using geophysical methods. They investigate the use of ferrofluids to enhance the efficiency of in-situ treatment and waste containment through (a) accurate guidance and delivery of reagent liquids to the desired subsurface contamination targets and/or (b) effective sweeping of the contaminated zone as ferrofluids move from the application point to an attracting magnet/collection point. They also investigate exploiting the strong magnetic signature of ferrofluids to develop a method for monitoring of liquid movement and position during injection using electromagnetic methods. The authors demonstrated the ability to induce ferrofluid movement in response to a magnetic field, and measured the corresponding magnetopressure. They demonstrated the feasibility of using conventional magnetometry for detecting subsurface zones of various shapes containing ferrofluids for tracing liquids injected for remediation or barrier formation. Experiments involving spherical, cylindrical and horizontal slabs showed a very good agreement between predictions and measurements
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Field Investigations of Lactate-Stimulated Bioreduction of Cr(VI) to Cr(III) at Hanford 100H
Ferromagnetic Convection in a Heterogeneous Darcy Porous Medium Using a Local Thermal Non-equilibrium (LTNE) Model
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Experimental investigation of magnetically driven flow of ferrofluids in porous media
This report presents experimental results of the flow of ferrofluids in porous media to investigate the potential for precisely controlling fluid emplacement in porous media using magnetic fields. Ferrofluids are colloidal suspensions of magnetic particles stabilized in various carrier liquids. In the presence of an external magnetic field, the ferrofluid becomes magnetized as the particles align with the magnetic field. Potential applications of ferrofluids to subsurface contamination problems include magnetic guidance of reactants to contaminated target zones in the subsurface for in situ treatment or emplacement of containment barriers. Laboratory experiments of magnetically induced ferrofluid flow in porous media in this report demonstrate the potential for mobilizing ferrofluid and controlling fluid emplacement through control of the external magnetic field. The pressures measured in ferrofluid due to the attraction of ferrofluid to a permanent magnet agree well with calculated values. The results show that a predictable pressure gradient is produced in the fluid which is strong near the magnet and drops off quickly with distance. This pressure gradient drives the fluid through sand without significant loss of ferrofluid strength due to filtration or dilution. Flow visualization experiments of ferrofluid in water-filled horizontal Hele-Shaw cells demonstrate that ferrofluid obtains a consistent final arc-shaped configuration around the magnet regardless of initial configuration or flow path toward the magnet. Analogous experiments in actual porous media showed similar features and confirm the ability of ferrofluid to move through porous media by magnetic forces
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Land disposal of San Luis drain sediments: Progress Report October 1998 through November 2000
Lawrence Berkeley National Laboratory (LBNL), in collaboration with the US Bureau of Reclamation and the Panoche Water District, is conducting a pilot-scale test of the viability of land application of selenium (Se)-enriched San Luis Drain (SLD) sediments. Local land disposal is an attractive option due to its low cost and the proximity of large areas of available land. Two modes of disposal are being tested: (1) the application to a nearby SLD embankment, and (2) the application to and incorporation with nearby farm soils. The study of these options considers the key problems which may potentially arise from this approach. These include disturbance of SLD sediments during dredging, resulting in increased downstream Se concentrations; movement of the land-applied Se to the groundwater; increased exposure to the biota; and reduced productivity of farm crops. This report describes field and laboratory activities carried out from 1998 through November 2000, as well as the results of these investigations
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Study of Microbial Community Structure Using Phospholipid Fatty Acid Analysis (PLFA) at a Chromium Contaminated Site
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Chemically defined medium for Desulfovibrio vulgaris stress studies and biomass production
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A Conceptual model of coupled biogeochemical and hydrogeological processes affected by in situ Cr(VI) bioreduction in groundwater at Hanford 100H Site
The overall objective of this presentation is to demonstrate a conceptual multiscale, multidomain model of coupling of biogeochemical and hydrogeological processes during bioremediation of Cr(VI) contaminated groundwater at Hanford 100H site. A slow release polylactate, Hydrogen Release Compound (HRCTM), was injected in Hanford sediments to stimulate immobilization of Cr(VI). The HRC injection induced a 2-order-of-magnitude increase in biomass and the onset of reducing biogeochemical conditions [e.g., redox potential decreased from +240 to -130 mV and dissolved oxygen (DO) was completely removed]. A three-well system, comprised of an injection well and upgradient and downgradient monitoring wells, was used for conducting the in situ biostimulation, one regional flow (no-pumping) tracer test, and five pumping tests along with the Br-tracer injection. Field measurements were conducted using a Br ion-selective electrode and a multiparameter flow cell to collect hourly data on temperature, pH, redox potential, electrical conductivity, and DO. Groundwater sampling was conducted by pumping through specially designed borehole water samplers. Cross-borehole radar tomography and seismic measurements were carried out to assess the site background lithological heterogeneity and the migration pathways of HRC byproducts through groundwater after the HRC injection