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Phase Liquid (phase + liquid)

Distribution by Scientific Domains
Engineering57%

Terms modified by Phase Liquid

  • phase liquid chromatography
    		•

    Selected Abstracts

    Simultaneous estimation of diffusive Volatile Organic Compound (VOC) fluxes and Non-Aqueous Phase Liquid (NAPL) saturation in the vadose zone

    GROUND WATER MONITORING & REMEDIATION, Issue 2 2005
    David Werner
    Soil-gas monitoring is a widely used tool to observe the migration of volatile organic compounds (VOCs) at contaminated sites. By combining this technique with natural gradient tracer methods, diffusive contaminant fluxes can be measured in situ, and non,aqueous phase liquid (NAPL) can be detected and roughly quantified. This work describes the new approach and its application at a field site in Denmark with an emplaced NAPL contamination. Soil-gas probes with a low dead volume were installed at 1-m depths in the sandy vadose zone, and a small volume of gas containing conservative and partitioning tracers was injected. Soil-gas samples were withdrawn subsequently during 1 to 4 h and analyzed simultaneously for VOCs and tracers. Tracers detected the NAPL reliably, and the combined data allowed for a close delineation of the source zone. The calculated NAPL saturation deviated by up to a factor of 3 from the analyses of soil cores. Better agreement was found by taking the NAPL composition into consideration, which is, however, generally unknown at the actual field sites. In addition, the tracers were also used to estimate effective diffusion coefficients in situ, which varied by a factor of 2 between various locations. From these data, diffusive contaminant vapor fluxes were quantified without additional laboratory experiments or the use of empirical relationships. The new approach yields a better site investigation with a few additional measurements. [source]

    Planning-level source decay models to evaluate impact of source depletion on remediation time frame

    REMEDIATION, Issue 4 2005
    Charles J. Newell
    A recent United States Environmental Protection Agency (US EPA) Expert Panel on Dense Nonaqueous Phase Liquid (DNAPL) Source Remediation concluded that the decision-making process for implementing source depletion is hampered by quantitative uncertainties and that few useful predictive tools are currently available for evaluating the benefits. This article provides a new planning-level approach to aid the process. Four simple mass balance models were used to provide estimates of the reduction in the remediation time frame (RTF) for a given amount of source depletion: step function, linear decay, first-order decay, and compound. As a shared framework for assessment, all models use the time required to remediate groundwater concentrations below a particular threshold (e.g., goal concentration or mass discharge rate) as a metric. This value is of interest in terms of providing (1) absolute RTF estimates in years as a function of current mass discharge rate, current source mass, the remediation goal, and the source- reduction factor, and (2) relative RTF estimates as a fraction of the remediation time frame for monitored natural attenuation (MNA). Because the latter is a function of the remediation goal and the remaining fraction (RF) of mass following remediation, the relative RTF can be a valuable aid in the decision to proceed with source depletion or to use a long-term containment or MNA approach. Design curves and examples illustrate the nonlinear relationship between the fraction of mass remaining following source depletion and the reduction in the RTF in the three decay-based models. For an example case where 70 percent of the mass was removed by source depletion and the remediation goal (Cg/C0) was input as 0.01, the improvement in the RTF (relative to MNA) ranged from a 70 percent reduction (step function model) to a 21 percent reduction (compound model). Because empirical and process knowledge support the appropriateness of decay-based models, the efficiency of source depletion in reducing the RTF is likely to be low at most sites (i.e., the percentage reduction in RTF will be much lower than the percentage of the mass that is removed by a source-depletion project). Overall, the anticipated use of this planning model is in guiding the decision-making process by quantifying the relative relationship between RTF and source depletion using commonly available site data. © 2005 Wiley Periodicals, Inc. [source]

    Discussion of a Comparison of Field Techniques for Confirming Dense Nonaqueous Phase Liquids by Terry W. Griffin and Kenneth W. Watson (2002), Ground Water Monitoring & Remediation, v. 22, no. 2, pages 48,59

    GROUND WATER MONITORING & REMEDIATION, Issue 2 2003
    Richard E. Jackson
    No abstract is available for this article. [source]

    Bioavailability of solid and non-aqueous phase liquid (NAPL)-dissolved phenanthrene to the biosurfactant-producing bacterium Pseudomonas aeruginosa 19SJ

    ENVIRONMENTAL MICROBIOLOGY, Issue 9 2001
    Marta García-Junco
    The biodegradation of phenanthrene by the biosurfactant-producing strain Pseudomonas aeruginosa 19SJ was investigated in experiments with the compound present either as crystals or dissolved in non-aqueous phase liquids (NAPLs). Growth on solid phenanthrene exhibited an initial phase not limited by dissolution rate and a subsequent, carbon-limited phase caused by exhaustion of the carbon source. Rhamnolipid biosurfactants were produced from solid phenanthrene and appeared in solution and particulate material (cells and phenanthrene crystals). During the carbon-limited phase, the concentration of rhamnolipids detected in culture exceeded the critical micelle concentration (CMC) determined with purified rhamnolipids. The biosurfactants caused a significant increase in dissolution rate and pseudosolubility of phenanthrene, but only at concentrations above the CMC. Externally added rhamnolipids at a concentration higher than the CMC increased the biodegradation rate of solid phenanthrene. Mineralization curves of low concentrations of phenanthrene initially dissolved in two NAPLs [2,2,4,4,6,8,8-heptamethylnonane and di(2-ethylhexyl)phthalate] were S-shaped, although no growth was observed in the population of suspended bacteria. Biosurfactants were not detected in solution under these conditions. The observed mineralization was attributed not only to suspended bacteria, but also to bacterial populations growing at the NAPL,water interface, mineralizing the compound at higher rates than predicted by abiotic partitioning. We suggest that rhamnolipid production and attachment increased the bioavailability of phenanthrene, so promoting biodegradation activity. [source]

    Simultaneous estimation of diffusive Volatile Organic Compound (VOC) fluxes and Non-Aqueous Phase Liquid (NAPL) saturation in the vadose zone

    GROUND WATER MONITORING & REMEDIATION, Issue 2 2005
    David Werner
    Soil-gas monitoring is a widely used tool to observe the migration of volatile organic compounds (VOCs) at contaminated sites. By combining this technique with natural gradient tracer methods, diffusive contaminant fluxes can be measured in situ, and non,aqueous phase liquid (NAPL) can be detected and roughly quantified. This work describes the new approach and its application at a field site in Denmark with an emplaced NAPL contamination. Soil-gas probes with a low dead volume were installed at 1-m depths in the sandy vadose zone, and a small volume of gas containing conservative and partitioning tracers was injected. Soil-gas samples were withdrawn subsequently during 1 to 4 h and analyzed simultaneously for VOCs and tracers. Tracers detected the NAPL reliably, and the combined data allowed for a close delineation of the source zone. The calculated NAPL saturation deviated by up to a factor of 3 from the analyses of soil cores. Better agreement was found by taking the NAPL composition into consideration, which is, however, generally unknown at the actual field sites. In addition, the tracers were also used to estimate effective diffusion coefficients in situ, which varied by a factor of 2 between various locations. From these data, diffusive contaminant vapor fluxes were quantified without additional laboratory experiments or the use of empirical relationships. The new approach yields a better site investigation with a few additional measurements. [source]

    Remediation of sites contaminated by oil refinery operations

    ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2006
    S. Khaitan
    The oil industry contributes to contamination of groundwater and aquifers beneath refineries and oil terminals. The successful remediation of a contaminated site requires understanding both the hydrogeology and the nature and extent of contamination. The physical,chemical and biological mechanisms that govern contaminant release, transport and fate in soils, sediments, and associated fluid phases must be understood and quantified. In addition, understanding the flow and entrapment of nonaqueous phase liquids (NAPLs) including lighter-than-water nonaqueous phase liquids (LNAPLs) in contaminated aquifers is important for the effective design of the recovery and remediation schemes. Current remedial technologies and risk assessment techniques to remediate former oil refinery sites contaminated by NAPLs are described in this paper. Emphasis is given to the most promising remediation techniques such as pump-and-treat, on-site bioremediation, phytoremediation, in situ soil washing, and thermal-based technologies, such as steam-enhanced extraction. Some enhancements to pump-and-treat techniques such as solvent flushing, polymer enhanced flushing, and air stripping are also discussed. Finally, important risk-based cleanup criteria associated with contaminated soil at refineries are presented. © 2005 American Institute of Chemical Engineers Environ Prog, 2005 [source]

    Treatment technology for remediation of wood preserving sites: Overview

    REMEDIATION, Issue 3 2000
    Edward R. Bates
    This is the first in a series of five articles describing the applicability, performance, and cost of technologies for the remediation of contaminated soil and water at wood preserving sites. Site-specific treatability studies conducted under the supervision of the United States Environmental Protection Agency (US EPA), National Risk Management Research Laboratory (NRMRL), from 1995 through 1997 constitute much of the basis for the evaluations presented, although data from other treatability studies, literature sources, and actual site remediations have also been included to provide a more comprehensive evaluation of remediation technologies. This article provides an overview of the wood preserving sites studied, including contaminant levels, and a summary of the performance of the technologies evaluated. The subsequent articles discuss the performance of each technology in more detail. Three articles discuss technologies for the treatment of soils, including solidification/stabilization, biological treatment, solvent extraction and soil washing. One article discusses technologies for the treatment of liquids, water and nonaqueous phase liquids (NAPLS), including biological treatment, carbon adsorption, photolytic oxidation, and hydraulic containment. The reader should be aware that other technologies including, but not limited to, incineration, thermal desorption, and base catalyzed dehalogenation, also have application for treating contaminants on wood preserving sites. They are not discussed in these five articles since the focus was to evaluate lesser known and hopefully lower cost approaches. However, the reader should include consideration of these other technologies as part of any evaluation or screening of technologies applicable to remediation of wood preserving sites. [source]