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Sample records for dnapl mass removal

  1. Mass discharge assessment at a brominated DNAPL site: Effects of known DNAPL source mass removal.

    PubMed

    Johnston, C D; Davis, G B; Bastow, T P; Woodbury, R J; Rao, P S C; Annable, M D; Rhodes, S

    2014-08-01

    Management and closure of contaminated sites is increasingly being proposed on the basis of mass flux of dissolved contaminants in groundwater. Better understanding of the links between source mass removal and contaminant mass fluxes in groundwater would allow greater acceptance of this metric in dealing with contaminated sites. Our objectives here were to show how measurements of the distribution of contaminant mass flux and the overall mass discharge emanating from the source under undisturbed groundwater conditions could be related to the processes and extent of source mass depletion. In addition, these estimates of mass discharge were sought in the application of agreed remediation targets set in terms of pumped groundwater quality from offsite wells. Results are reported from field studies conducted over a 5-year period at a brominated DNAPL (tetrabromoethane, TBA; and tribromoethene, TriBE) site located in suburban Perth, Western Australia. Groundwater fluxes (qw; L(3)/L(2)/T) and mass fluxes (Jc; M/L(2)/T) of dissolved brominated compounds were simultaneously estimated by deploying Passive Flux Meters (PFMs) in wells in a heterogeneous layered aquifer. PFMs were deployed in control plane (CP) wells immediately down-gradient of the source zone, before (2006) and after (2011) 69-85% of the source mass was removed, mainly by groundwater pumping from the source zone. The high-resolution (26-cm depth interval) measures of qw and Jc along the source CP allowed investigation of the DNAPL source-zone architecture and impacts of source mass removal. Comparable estimates of total mass discharge (MD; M/T) across the source zone CP reduced from 104gday(-1) to 24-31gday(-1) (70-77% reductions). Importantly, this mass discharge reduction was consistent with the estimated proportion of source mass remaining at the site (15-31%). That is, a linear relationship between mass discharge and source mass is suggested. The spatial detail of groundwater and mass flux distributions

  2. Mass discharge assessment at a brominated DNAPL site: Effects of known DNAPL source mass removal

    NASA Astrophysics Data System (ADS)

    Johnston, C. D.; Davis, G. B.; Bastow, T. P.; Woodbury, R. J.; Rao, P. S. C.; Annable, M. D.; Rhodes, S.

    2014-08-01

    Management and closure of contaminated sites is increasingly being proposed on the basis of mass flux of dissolved contaminants in groundwater. Better understanding of the links between source mass removal and contaminant mass fluxes in groundwater would allow greater acceptance of this metric in dealing with contaminated sites. Our objectives here were to show how measurements of the distribution of contaminant mass flux and the overall mass discharge emanating from the source under undisturbed groundwater conditions could be related to the processes and extent of source mass depletion. In addition, these estimates of mass discharge were sought in the application of agreed remediation targets set in terms of pumped groundwater quality from offsite wells. Results are reported from field studies conducted over a 5-year period at a brominated DNAPL (tetrabromoethane, TBA; and tribromoethene, TriBE) site located in suburban Perth, Western Australia. Groundwater fluxes (qw; L3/L2/T) and mass fluxes (Jc; M/L2/T) of dissolved brominated compounds were simultaneously estimated by deploying Passive Flux Meters (PFMs) in wells in a heterogeneous layered aquifer. PFMs were deployed in control plane (CP) wells immediately down-gradient of the source zone, before (2006) and after (2011) 69-85% of the source mass was removed, mainly by groundwater pumping from the source zone. The high-resolution (26-cm depth interval) measures of qw and Jc along the source CP allowed investigation of the DNAPL source-zone architecture and impacts of source mass removal. Comparable estimates of total mass discharge (MD; M/T) across the source zone CP reduced from 104 g day- 1 to 24-31 g day- 1 (70-77% reductions). Importantly, this mass discharge reduction was consistent with the estimated proportion of source mass remaining at the site (15-31%). That is, a linear relationship between mass discharge and source mass is suggested. The spatial detail of groundwater and mass flux distributions also

  3. DNAPL REMOVAL MECHANISMS AND MASS TRANSFER CHARACTERISTICS DURING COSOLVENT-AIR FLOODING

    EPA Science Inventory

    The concurrent injection of cosolvent and air, a cosolvent-air (CA) flood was recently suggested for a dense nonaqueous phase liquid (DNAPL) remediation technology. The objectives of this study were to elucidate the DNAPL removal mechanisms of the CA flood and to quantify mass t...

  4. DNAPL REMOVAL MECHANISMS AND MASS TRANSFER CHARACTERISTICS DURING COSOLVENT-AIR FLOODING

    EPA Science Inventory

    The concurrent injection of cosolvent and air, a cosolvent-air (CA) flood was recently suggested for a dense nonaqueous phase liquid (DNAPL) remediation technology. The objectives of this study were to elucidate the DNAPL removal mechanisms of the CA flood and to quantify mass t...

  5. Linking Contaminant Mass Discharge to DNAPL Source Zone Architecture and Mass Removal

    NASA Astrophysics Data System (ADS)

    Pennell, K. D.; Suchomel, E. J.; Amos, B. K.; Loeffler, F. E.; Capiro, N. L.

    2007-05-01

    To evaluate the relationship between partial dense nonaqueous phase (DNAPL) mass removal and plume behavior, laboratory-scale experiments were conducted in a two-dimensional aquifer cell containing a tetrachloroethene (PCE) source zone and a down-gradient plume region. PCE-DNAPL saturation distributions were quantified using a light transmission system and expressed in terms of a ganglia-to-pool (GTP) volume ratio. To achieve incremental mass removal, the aquifer cells were flushed with a 4% Tween 80 surfactant solution that increased the solubility of PCE by more than two orders-of-magnitude with minimal mobilization of entrapped PCE-DNAPL. For a ganglia-dominated source zone (GTP = 1.6) greater than 70% mass removal was required before measurable reductions in mass discharge were realized, while for pool-dominated source zones (GTP < 0.3) reductions in mass discharge versus mass removal approached a 1:1 correlation. Current experiments are designed to evaluate the potential for coupling aggressive mass removal with microbial reductive dechlorination.

  6. A framework for assessing risk reduction due to DNAPL mass removal from low permeability soils

    SciTech Connect

    Freeze, R.A.; McWhorter, D.B.

    1996-08-01

    Many emerging remediation technologies are designed to remove contaminant mass from source zones at DNAPL sites in response to regulatory requirements. There is often concern in the regulated community as to whether mass removal actually reduces risk, or whether the small risk reductions achieved warrant the large costs incurred. This paper sets out a framework for quantifying the degree to which risk is reduced as mass is removed from shallow, saturated, low-permeability, dual-porosity, DNAPL source zones. Risk is defined in terms of meeting an alternate concentration level (ACL) at a compliance well in an aquifer underlying the source zone. The ACL is back-calculated from a carcinogenic health-risk characterization at a downstream water-supply well. Source-zone mass-removal efficiencies are heavily dependent on the distribution of mass between media (fractures, matrix) and phases (dissolved, sorbed, free product). Due to the uncertainties in currently-available technology performance data, the scope of the paper is limited to developing a framework for generic technologies rather than making risk-reduction calculations for specific technologies. Despite the qualitative nature of the exercise, results imply that very high mass-removal efficiencies are required to achieve significant long-term risk reduction with technology, applications of finite duration. 17 refs., 7 figs., 6 tabs.

  7. Surfactant Enhanced DNAPL Removal

    DTIC Science & Technology

    2001-08-01

    or the permeability contrast (i.e., degree of heterogeneity) that is present in the DNAPL zone. To solubilize DNAPL with surfactants, a sufficient...with respect to the effects of permeability and heterogeneity upon the costs of SEAR: as permeability decreases and/or the degree of heterogeneity...not be an issue for surfactant recovery at all sites. The degree to which MEUF will concentrate the calcium is a function of the surfactant itself

  8. Coupling Aggressive Mass Removal with Microbial Reductive Dechlorination for Remediation of DNAPL Source Zones: A Review and Assessment

    PubMed Central

    Christ, John A.; Ramsburg, C. Andrew; Abriola, Linda M.; Pennell, Kurt D.; Löffler, Frank E.

    2005-01-01

    The infiltration of dense non-aqueous-phase liquids (DNAPLs) into the saturated subsurface typically produces a highly contaminated zone that serves as a long-term source of dissolved-phase groundwater contamination. Applications of aggressive physical–chemical technologies to such source zones may remove > 90% of the contaminant mass under favorable conditions. The remaining contaminant mass, however, can create a rebounding of aqueous-phase concentrations within the treated zone. Stimulation of microbial reductive dechlorination within the source zone after aggressive mass removal has recently been proposed as a promising staged-treatment remediation technology for transforming the remaining contaminant mass. This article reviews available laboratory and field evidence that supports the development of a treatment strategy that combines aggressive source-zone removal technologies with subsequent promotion of sustained microbial reductive dechlorination. Physical–chemical source-zone treatment technologies compatible with posttreatment stimulation of microbial activity are identified, and studies examining the requirements and controls (i.e., limits) of reductive dechlorination of chlorinated ethenes are investigated. Illustrative calculations are presented to explore the potential effects of source-zone management alternatives. Results suggest that, for the favorable conditions assumed in these calculations (i.e., statistical homogeneity of aquifer properties, known source-zone DNAPL distribution, and successful bioenhancement in the source zone), source longevity may be reduced by as much as an order of magnitude when physical–chemical source-zone treatment is coupled with reductive dechlorination. PMID:15811838

  9. Contaminant Mass Discharge and Mass Removal Behavior for a DNAPL Field Site

    NASA Astrophysics Data System (ADS)

    Brusseau, M. L.; Matthieu, D. E.; Carroll, K. C.; Mainhagu, J.; Morrison, C. N.; Mcmillan, A. L.; Russo, A. E.; Plaschke, M.

    2012-12-01

    The use of contaminant-mass-discharge measurements to characterize site conditions and remediation performance is becoming more widespread. Almost all applications to date have been based on conducting one or two discrete measurements (e.g., collected before and after a remedial action). While this approach provides useful information, additional insight can be gained by measuring time-continuous profiles of contaminant mass discharge (CMD). The objective of this study was to characterize the temporal behavior of contaminant mass discharge, and the relationship between reductions in CMD and reductions in contaminant mass, for a very heterogeneous, highly contaminated source-zone field site. Trichloroethene is the primary contaminant of concern, and several lines of evidence indicate the presence of organic liquid in the subsurface. The site is undergoing groundwater extraction for source control, and contaminant mass discharge has been monitored since system start-up 5 years ago. The results show a significant reduction in contaminant mass discharge with time, which has decreased from approximately 1 to 0.15 kg/d. Comparison of two sets of core data, collected 3.5 years apart, suggests that a significant reduction in aggregate sediment-phase TCE concentrations, ~80%, occurred between sampling events. These data were used to characterize the relationship between reductions in contaminant mass discharge and reductions in contaminant mass. The curvilinear, convex-upward relationship observed is consistent with a system wherein significant quantities of mass are present in hydraulically poorly accessible domains for which mass removal is influenced by rate-limited mass transfer.

  10. Surfactant-Enhanced DNAPL Removal

    DTIC Science & Technology

    2001-08-24

    DNAPL SOURCE REMEDIATION AT SITE 88, MARINE CORPS BASE CAMP LEJEUNE vii AATDF AFCEE AFB AFP4 AQT B bgs CERCLA CITT em cmc cp cu d de DE&S DNAPL DoD...liquid meter(s) medium, middle Marine Corps Base maximum contaminant level millidarcies micellar-enhanced ultrafiltration unit minute(s) multi-level...present in the subsurface adjacent to a dry-cleaning facility operated by the Marine Corps Base (MCB) Camp Lejeune, North Carolina. The contaminant was

  11. Evaluating the Relationship Between Source Zone Metrics and Down-Gradient Plume Response as a Function of Mixed DNAPL Mass Removal

    NASA Astrophysics Data System (ADS)

    Cápiro, N. L.; Granbery, E. K.; Christ, J.; Pennell, K. D.

    2009-12-01

    phase was proportional to the mole fraction in the NAPL, consistent with a Raoult’s Law. It is hypothesized that the deviations from Raoult’s Law observed for PCE and TCE were caused by preferential solubilization of PCE within the hydrophobic core of the micelles. Work is on-going to quantify the preferential solubilization observed in the batch experiments, which will facilitate the incorporation of this relationship into multiphase compositional simulators. These simulators will then be used to improve the understanding of the inter-relationships between the initial source zone architecture, mass removal, reductions in mass flux and plume evolution in multi-component contaminated subsurface systems.

  12. Predicting DNAPL mass discharge from pool-dominated source zones.

    PubMed

    Christ, John A; Ramsburg, C Andrew; Pennell, Kurt D; Abriola, Linda M

    2010-05-20

    Models that link simplified descriptions of dense non-aqueous phase liquid (DNAPL) source zone architecture with predictions of mass flux can be effective screening tools for evaluation of source zone management strategies. Recent efforts have focused on the development and implementation of upscaled models to approximate the relationship between mass removal and flux-averaged, down-gradient contaminant concentration (or mass flux) reduction. The efficacy of these methods has been demonstrated for ganglia-dominated source zones. This work extends these methods to source zones dominated by high-saturation DNAPL pools. An existing upscaled mass transfer model was modified to reproduce dissolution behavior in pool-dominated scenarios by employing a two-domain (ganglia and pools) representation of the source zone. The two-domain upscaled model is parameterized using the initial fraction of the source zone that exists as pool regions, the initial fraction of contaminant eluting from these pool regions, and the flux-averaged down-gradient contaminant concentration. Comparisons of model predictions with a series of three-dimensional source zone numerical simulations and data from two-dimensional aquifer cell experiments demonstrate the ability of the model to predict DNAPL dissolution from ganglia- and pool-dominated source zones for all levels of mass recovery.

  13. IMPACT OF DNAPL SOURCE TREATMENT ON CONTAMINANT MASS FLUX

    EPA Science Inventory

    Implementation of remediation technologies at DNAPL contaminated sites has shown that large quantities of contaminants can be removed or degraded using in-situ heating, flushing or oxidation. The rate and magnitude of DNAPL removal is dependent upon site-specific and technology-...

  14. Composition Dependent Evolution in Mass Flux from Binary Trichloroethene/Tetrachloroethene-DNAPL Source Zones

    NASA Astrophysics Data System (ADS)

    Walker, D. I.; Cápiro, N. L.; Granbery, E. K.; Pennell, K. D.

    2010-12-01

    In order to accurately predict the efficacy of subsurface remediation for sites contaminated with multicomponent dense non-aqueous phase liquids (DNAPLs), it is necessary to link changes in aqueous phase contaminant discharge with source composition and distribution. Dissolution from a binary 1:1 (molar) mixture of trichloroethene- (TCE) and tetrachloroethene- (PCE) DNAPL was measured in three separate 2-dimensional aquifer cells (100 x 48 x 1.4 cm) that were packed with different background media (1:1 mixture 20:30 and 40:50 mesh; 20:30 mesh and 40:50 mesh Accusand) and low permeability zones. Initial DNAPL source zone architectures were varied to yield ganglia to pool (GTP) ratios of 0.44, 1.56, and 1.72. Down-gradient plume evolution and DNAPL spatial distribution were measured every 5 pore volumes (PV) from side port samples and a light transmission system that allowed non-invasive measurement of volumetric DNAPL saturation and source descriptive metrics at a resolution of 0.03 to 0.08 mm2. Flux-averaged PCE and TCE effluent concentrations were measured every 0.7 PVs from a fully screened effluent chamber. To accelerate changes in source zone architecture and overall mass removal, two surfactant floods (4% w/w Tween 80) were completed after mass discharge from the source zone reached a steady state. Mass flux reductions for a given amount of DNAPL mass removed were found to correspond strongly to the molar composition of DNAPL in the source zone and the initial DNAPL saturation distribution metric (e.g., GTP). Percent reductions in mass flux from the aquifer cells with ganglia dominated architectures were 98 and 72% for TCE and PCE respectively, with a final overall NAPL source zone molar ratio of 0.49:0.51 TCE: PCE ; and 97 and 79% for TCE and PCE with molar ratios of 0.19:0.81 TCE:PCE. Reductions in mass flux from the pool dominated source zone were 90 and 53% for TCE and PCE with a final overall DNAPL source zone mole fraction of 0.26:0.74 TCE:PCE. These

  15. Coupling Surfactants with Permanganate for PCE DNAPL Removal: Coinjection or Sequential Application as Delivery Methods

    NASA Astrophysics Data System (ADS)

    Dugan, P. J.; Siegrist, R. L.; Crimi, M. L.

    2008-12-01

    Batch experiments and two-dimensional (2-D) flow-through cell experiments were conducted to investigate coupling surfactant-enhanced aquifer remediation (SEAR) with in situ chemical oxidation (ISCO) of tetrachloroethene (PCE) dense nonaqueous phase liquid (DNAPL) for PCE mass destruction. Previous batch screening tests were performed on surfactants and cosolvents in the presence of the oxidant potassium permanganate, to assess compatibility for coupling with permanganate. The anionic surfactants sodium dioctyl sulfosuccinate (Aerosol OT), and sodium hexadecyl diphenyl oxide disulfonate (Dowfax 8390) were compatible and selected for use. Two delivery methods were investigated: (1) coinjection of 0.66 pore volumes (PVs) of 1.0-wt% Aerosol-OT, 0.5-wt% Dowfax 8390, 0.35-wt% CaBr2, and 0.75-wt% NaBr, (for enhanced PCE solubilization) with 0.5-wt% permanganate(for DNAPL mass destruction), and (2) sequential application of 0.66 PVs of the same surfactant solution followed by 0.66 PVs of 0.5-wt% permanganate flush. The 2-D cell packing configuration consisted of a fine-grained silica sand matrix with an embedded medium- grained sand lens, which allowed for the development of a high saturation PCE DNAPL source zone (~9-11% v/v) within the lens of each cell. For both experiments the flushing solutions were delivered at a linear velocity of 52 cm/day. Water quality samples were collected from eight point sampling ports, as well as the cell effluent. Samples were analyzed for PCE, chloride, and permanganate. At the conclusion of the experiments, the mass of PCE removed was quantified by destructively analyzing the cell. Results indicate complete mass removal using sequential application as a delivery method. In the coinjection experiment, cores extracted at the conclusion revealed that 99.8% of PCE DNAPL mass was removed. However, it was not possible to close a mass balance between the initial PCE added and the PCE removed. It is hypothesized this result was due to incomplete

  16. The significance of heterogeneity on mass flux from DNAPL source zones: an experimental investigation.

    PubMed

    Page, John W E; Soga, Kenichi; Illangasekare, Tissa

    2007-12-07

    Understanding the process of mass transfer from source zones of aquifers contaminated with organic chemicals in the form of dense non-aqueous phase liquids (DNAPL) is of importance in site management and remediation. A series of intermediate-scale tank experiments was conducted to examine the influence of aquifer heterogeneity on DNAPL mass transfer contributing to dissolved mass emission from source zone into groundwater under natural flow before and after remediation. A Tetrachloroethylene (PCE) spill was performed into six source zone models of increasing heterogeneity, and both the spatial distribution of the dissolution behavior and the net effluent mass flux were examined. Experimentally created initial PCE entrapment architecture resulting from the PCE migration was largely influenced by the coarser sand lenses and the PCE occupied between 30 and 60% of the model aquifer depth. The presence of DNAPL had no apparent effect on the bulk hydraulic conductivity of the porous media. Up to 71% of PCE mass in each of the tested source zone was removed during a series of surfactant flushes, with associated induced PCE mobilization responsible for increasing vertical DNAPL distributions. Effluent mass flux due to water dissolution was also found to increase progressively due to the increase in NAPL-water contact area even though the PCE mass was reduced. Doubling of local groundwater flow velocities showed negligible rate-limited effects at the scale of these experiments. Thus, mass transfer behavior was directly controlled by the morphology of DNAPL within each source zone. Effluent mass flux values were normalized by the up-gradient DNAPL distributions. For the suite of aquifer heterogeneities and all remedial stages, normalized flux values fell within a narrow band with mean of 0.39 and showed insensitivity to average source zone saturations.

  17. DNAPL remediation with in situ chemical oxidation using potassium permanganate - II. Increasing removal efficiency by dissolving Mn oxide precipitates

    NASA Astrophysics Data System (ADS)

    Li, X. David; Schwartz, Franklin W.

    2004-02-01

    In situ chemical oxidation (ISCO) schemes using MnO 4- have been effective in destroying chlorinated organic solvents dissolved in ground water. Laboratory experiments and field pilot tests reveal that the precipitation of Mn oxide, one of the reaction products, causes a reduction of permeability, which can lead to flow bypassing and inefficiency of the scheme. Without a solution to this problem of plugging, it is difficult to remove DNAPL from the subsurface completely. In a companion paper, we showed with batch experiments that Mn oxide can be dissolved rapidly with certain organic acids. This study utilizes 2-D flow-tank experiments to examine the possibility of nearly complete DNAPL removal by ISCO with MnO 4-, when organic acids are used to remove Mn oxide. The experiments were conducted in a small 2-D glass flow tank containing a lenticular silica-sand medium. Blue-dyed trichloroethylene (TCE) provided residual, the perched and pooled DNAPL. KMnO 4 at 200 mg/l was flushed through the DNAPL horizontally. Once plugging reduced permeability and prevented further delivery of the oxidant, citric or oxalic acids were pumped into the flow tank to dissolve the Mn oxide precipitates. Organic ligands removed the Mn oxide precipitates relatively quickly, and permitted another cycle of MnO 4- flooding. Cycles of MnO 4-/acid flooding continued until all of the visible DNAPL was removed. The experiments were monitored with chemical analysis and visualization. A mass-balance calculation indicated that by the end of the experiments, all the DNAPL was removed. The results show also how heterogeneity adds complexity to initial redistribution of DNAPL, and to the efficiency of the chemical flooding.

  18. FIELD AND LABORATORY EVALUATION OF DNAPL REMEDIAL PERFORMANCE

    EPA Science Inventory

    The basic goal of DNAPL source treatment is to reduce health and environmental risks posed by the DNAPL contamination. Removing a sufficient mass of DNAPL to achieve concentration-based regulatory goals is difficult because of site hydrogeologic heterogeneity and uncertainties ab...

  19. Influence of mass transfer characteristics for DNAPL source depletion and contaminant flux in a highly characterized glaciofluvial aquifer

    NASA Astrophysics Data System (ADS)

    Maji, R.; Sudicky, E. A.

    2008-11-01

    The transfer of contaminant mass between the nonaqueous- and aqueous-phases is a process of central importance for the remediation of sites contaminated by dense nonaqueous-phase liquids (DNAPLs). This paper describes a comparison of the results obtained with various alternative DNAPL-aqueous-phase mass transfer models contained in the literature for predicting DNAPL source-zone depletion times in groundwater systems. These dissolution models were largely developed through laboratory column experiments. To gain insight into the implications of various representations of the local-scale kinetic as well as equilibrium DNAPL dissolution processes, aquifer heterogeneity and the complex architecture of a DNAPL source-zone, the aqueous-phase contaminant concentrations and mass fluxes arriving at a down-gradient compliance boundary are analyzed in a conditional stochastic framework. The hydrogeologic setting is a heterogeneous fluvial aquifer in Southwest Germany, referred to as the aquifer analog dataset, that was intensively characterized in three dimensions for hydrogeological parameters that include permeability, effective porosity, grain size, mineralogy and sorption coefficients. By embedding the various dissolution models into the compositional, multiphase flow model, CompFlow, the relative times predicted for complete depletion of a released DNAPL source due to natural dissolution are explored. Issues related to achieving environmental benefits through, for example, partial DNAPL-zone source removal via enhanced remedial technologies are also discussed. In this context, performance metrics in the form of peak aqueous-phase contaminant concentrations and mass fluxes arriving at a down-gradient compliance boundary are compared to each other. This is done for each of the alternative mass transfer models. A significant reduction in the fractional flux at a downstream location from the DNAPL source can be achieved by partial source-zone mass reduction; however, peak

  20. Influence of mass transfer characteristics for DNAPL source depletion and contaminant flux in a highly characterized glaciofluvial aquifer.

    PubMed

    Maji, R; Sudicky, E A

    2008-11-14

    The transfer of contaminant mass between the nonaqueous- and aqueous-phases is a process of central importance for the remediation of sites contaminated by dense nonaqueous-phase liquids (DNAPLs). This paper describes a comparison of the results obtained with various alternative DNAPL-aqueous-phase mass transfer models contained in the literature for predicting DNAPL source-zone depletion times in groundwater systems. These dissolution models were largely developed through laboratory column experiments. To gain insight into the implications of various representations of the local-scale kinetic as well as equilibrium DNAPL dissolution processes, aquifer heterogeneity and the complex architecture of a DNAPL source-zone, the aqueous-phase contaminant concentrations and mass fluxes arriving at a down-gradient compliance boundary are analyzed in a conditional stochastic framework. The hydrogeologic setting is a heterogeneous fluvial aquifer in Southwest Germany, referred to as the aquifer analog dataset, that was intensively characterized in three dimensions for hydrogeological parameters that include permeability, effective porosity, grain size, mineralogy and sorption coefficients. By embedding the various dissolution models into the compositional, multiphase flow model, CompFlow, the relative times predicted for complete depletion of a released DNAPL source due to natural dissolution are explored. Issues related to achieving environmental benefits through, for example, partial DNAPL-zone source removal via enhanced remedial technologies are also discussed. In this context, performance metrics in the form of peak aqueous-phase contaminant concentrations and mass fluxes arriving at a down-gradient compliance boundary are compared to each other. This is done for each of the alternative mass transfer models. A significant reduction in the fractional flux at a downstream location from the DNAPL source can be achieved by partial source-zone mass reduction; however, peak

  1. Surfactant foam technology for in situ removal of heavy chlorinated compounds-DNAPLs.

    PubMed

    Maire, Julien; Coyer, Amandine; Fatin-Rouge, Nicolas

    2015-12-15

    The use of surfactant foam for the remediation of a saturated soil contaminated with a dense non-aqueous phase liquid (DNAPL) was investigated at bench-scale. Despite the presence of the DNAPL, high foam stability was obtained for a mixture of cocamidopropyl betaïne and dodecylsulfate at 0.05%. Foams were assessed in different injection conditions and were compared to commonly used remediation methods. Strong foams improved significantly the DNAPL recovery yield, which amounted up to 98%, owing to the propagation of a flat foam front, with low dissolution (<0.5 g l(-1)) and surfactant consumption (<10 g kg(-1) DNAPL recovered). The effects of important parameters (gas to liquid ratio, injection velocity, gas nature) and methods for foam production on pressure gradient (∇P), remediation efficiency and surfactant consumption were investigated. Even for low injection velocities (4×10(-4) ms(-1)), capillary numbers were high enough (∼8×10(-3)) to push the DNAPL efficiently. DNAPL lowered ∇P for foam propagation because of its destabilising effect. The use of CO2 as gas reduced the ∇Ps for foam propagation by 35%. ∇P were also decreased by 25% for gas to liquid ratios lower than 75%, whereas, DNAPL removal remained high. This technology should lower spreading risks and treatment costs.

  2. Removal of trichloroethylene DNAPL trapped in porous media using nanoscale zerovalent iron and bimetallic nanoparticles: direct observation and quantification.

    PubMed

    Wang, Qiliang; Jeong, Seung-Woo; Choi, Heechul

    2012-04-30

    Direct trichloroethylene (TCE) dense non-aqueous phase liquid (DNAPL) removal inside pore areas using nanoscale zerovalent iron (NZVI) and bimetallic nanoparticles were first investigated in a water-saturated porous glass micromodel. Effects of nitrate, aqueous ethanol co-solvent, humic substance, and elapsed time on TCE DNAPL removal using NZVI were studied by direct visualization. The removal efficiency was then quantified by directly measuring the remaining TCE DNAPL blobs area using an image analyzer. As ethanol content of co-solvent increased, TCE DNAPL removal by NZVI was also increased implying sequential TCE DNAPL removal mechanisms: as dissolved TCE was degraded by NZVI, TCE dissolution from TCE blobs would be then facilitated and the TCE blob areas would be eventually reduced. The presence of nitrate and humic substance hindered the NZVI reactivity for the TCE DNAPL removal. In contrast, the TCE DNAPL removal efficiency was enhanced using bimetallic nanoparticles in a short-term reaction by generating atomic hydrogen for catalytic hydro-dechlorination. However, all TCE DNAPL removal efficiencies reached the same level after long-term reaction using both NZVI and bimetallic nanoparticles. Direct TCE DNAPL observation clearly implied that TCE blobs existed for long time even though all TCE blobs were fully exposed to NZVI and bimetallic nanoparticles. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Plume Development and Mass Flux Following Surfactant-Based Treatment of Heterogeneous PCE-DNAPL Source Zones

    NASA Astrophysics Data System (ADS)

    Suchomel, E. J.; Pennell, K. D.

    2004-12-01

    The zones of contamination at typical chlorinated solvent-contaminated sites can be divided into two regions: a source zone in which free-phase contaminants (dense nonaqueous phase liquids, or DNAPLs) are present, and a solute plume containing only dissolved-phase contaminants. Currently, pump-and-treat is the most common method for achieving dissolved-phase plume containment; however, it is widely recognized that this approach is generally ineffective for source zone mass removal. As a result, a number of innovative technologies for in situ DNAPL source zone treatment have been developed, but mass removal using these methods is often incomplete. In addition, the effects of partial source zone mass removal on subsequent dissolved-phase plume development and contaminant flux remain poorly understood. To address these issues laboratory-scale experiments were conducted in a two dimensional (2-D) aquifer cell having overall dimensions of 150 cm (length) by 48 cm (height) by 1.4 cm (internal thickness) and containing both source zone and down-gradient "plume" regions. The aquifer cells were packed under water-saturated conditions with Accusand (either 20/30 sieve size or a mixture of 50% 20/30 and 50% 40/50 sieve sizes). Within the source zone, three layers of F-70 Ottawa sand lenses were emplaced to mimic heterogeneous regions of lower permeability media. Following tetrachloroethene (PCE) release and redistribution in the source zone, a solubilizing surfactant solution containing 4% Tween 80 was used to achieve sequential PCE mass removals ranging from 30% to 80%. At the conclusion of each surfactant flood, down-gradient contaminant concentrations and mass fluxes were monitored at a hydraulic gradient of 1x10-3. The PCE-DNAPL distributions in the source zone were quantified using light transmission prior to and following each surfactant flood. PCE-DNAPL distribution was expressed in terms of a ganglia to pool ratio (G:P), for which the volume of PCE above residual

  4. IMPACTS OF DNAPL SOURCE TREATMENT ON CONTAMINANT MASS FLUX

    EPA Science Inventory

    Current remedial techniques are unable to completely eliminate all dense nonaqueous phase liquid (DNAPL) from source zone areas at most sites, and conflicting views on the benefits of partial DNAPL source zone remediation exist in the literature. A comparison of contaminant flux...

  5. EVALUATIONS OF DNAPL REMEDIAL PERFORMANCE BASED ON FIELD MEASUREMENTS OF CONTAMINANT FLUX

    EPA Science Inventory

    Under a concentration-based regulatory framework, the benefits of conducting dense nonaqueous phase liquid (DNAPL) source-zone remediation are questionable because of the impracticality of complete DNAPL elimination at most sites. Removing a sufficient mass of DNAPL to achieve c...

  6. EVALUATIONS OF DNAPL REMEDIAL PERFORMANCE BASED ON FIELD MEASUREMENTS OF CONTAMINANT FLUX

    EPA Science Inventory

    Under a concentration-based regulatory framework, the benefits of conducting dense nonaqueous phase liquid (DNAPL) source-zone remediation are questionable because of the impracticality of complete DNAPL elimination at most sites. Removing a sufficient mass of DNAPL to achieve c...

  7. SERDP AND NRMRL SPONSOR FIELD TEST OF COSOLVENT-ENHANCED DNAPL REMOVAL

    EPA Science Inventory

    A field test of multicomponent cosolvent flooding for in-situ remediation of DNAPL source zones was conducted at the Dover National Test Site (DNTS) at Dover Air Force Base, Delaware, in July, 2001. The test was part of an Enhanced Source Removal (ESR) demonstration project fund...

  8. SERDP AND NRMRL SPONSOR FIELD TEST OF COSOLVENT-ENHANCED DNAPL REMOVAL

    EPA Science Inventory

    A field test of multicomponent cosolvent flooding for in-situ remediation of DNAPL source zones was conducted at the Dover National Test Site (DNTS) at Dover Air Force Base, Delaware, in July, 2001. The test was part of an Enhanced Source Removal (ESR) demonstration project fund...

  9. Determining Mass and Persistence of a Reactive Brominated-Solvent DNAPL Source Using Mass Depletion-Mass Flux Reduction Relationships During Pumping

    NASA Astrophysics Data System (ADS)

    Johnston, C. D.; Davis, G. B.; Bastow, T.; Annable, M. D.; Trefry, M. G.; Furness, A.; Geste, Y.; Woodbury, R.; Rhodes, S.

    2011-12-01

    Measures of the source mass and depletion characteristics of recalcitrant dense non-aqueous phase liquid (DNAPL) contaminants are critical elements for assessing performance of remediation efforts. This is in addition to understanding the relationships between source mass depletion and changes to dissolved contaminant concentration and mass flux in groundwater. Here we present results of applying analytical source-depletion concepts to pumping from within the DNAPL source zone of a 10-m thick heterogeneous layered aquifer to estimate the original source mass and characterise the time trajectory of source depletion and mass flux in groundwater. The multi-component, reactive DNAPL source consisted of the brominated solvent tetrabromoethane (TBA) and its transformation products (mostly tribromoethene - TriBE). Coring and multi-level groundwater sampling indicated the DNAPL to be mainly in lower-permeability layers, suggesting the source had already undergone appreciable depletion. Four simplified source dissolution models (exponential, power function, error function and rational mass) were able to describe the concentration history of the total molar concentration of brominated organics in extracted groundwater during 285 days of pumping. Approximately 152 kg of brominated compounds were extracted. The lack of significant kinetic mass transfer limitations in pumped concentrations was notable. This was despite the heterogeneous layering in the aquifer and distribution of DNAPL. There was little to choose between the model fits to pumped concentration time series. The variance of groundwater velocities in the aquifer determined during a partitioning inter-well tracer test (PITT) were used to parameterise the models. However, the models were found to be relatively insensitive to this parameter. All models indicated an initial source mass around 250 kg which compared favourably to an estimate of 220 kg derived from the PITT. The extrapolated concentrations from the

  10. The use of mass depletion-mass flux reduction relationships during pumping to determine source zone mass of a reactive brominated-solvent DNAPL.

    PubMed

    Johnston, C D; Davis, G B; Bastow, T P; Annable, M D; Trefry, M G; Furness, A; Geste, Y; Woodbury, R J; Rao, P S C; Rhodes, S

    2013-01-01

    Mass depletion-mass flux relationships usually applied to a groundwater plume were established at field scale for groundwater pumped from within the source zone of a dense non-aqueous phase liquid (DNAPL). These were used as part of multiple lines of evidence in establishing the DNAPL source mass and architecture. Simplified source mass-dissolved concentration models including those described by exponential, power, and error functions as well as a rational mass equation based on the equilibrium stream tube approach were fitted to data from 285 days of source zone pumping (SZP) from a single well which removed 152 kg of dissolved organics from a multi-component, reactive brominated solvent DNAPL. The total molar concentration of the source compound, tetrabromoethane and its daughter products was used as a single measure of contaminant concentration to relate to source mass. A partitioning inter-well tracer test (PITT) conducted prior to the SZP provided estimates of groundwater travel times, enabling parameterisation of the models. After accounting for capture of the down-gradient dissolved plume, all models provided a good fit to the observed data. It was shown that differentiation between models would only emerge after appreciably more pumping from the source zone. The model fits were not particularly sensitive to the exponent parameters and variance of groundwater travel time. In addition, the multi-component nature of the DNAPL did not seem to affect the utility of the models for the period examined. Estimates of the DNAPL mass prior to the start of SZP from the models were greatest where the log of the variance of travel time was used explicitly in the source depletion models (mean 295kg) compared to where the associated power exponent and variance was fitted freely (mean 258 kg). The estimates of source mass were close to that of 220kg determined from the PITT. In addition to the PITT, multi-level groundwater sampling from within the source zone provided

  11. Mass Transfer Limited Enhanced Bioremediation at Dnapl Source Zones: a Numerical Study

    NASA Astrophysics Data System (ADS)

    Kokkinaki, A.; Sleep, B. E.

    2011-12-01

    The success of enhanced bioremediation of dense non-aqueous phase liquids (DNAPLs) relies on accelerating contaminant mass transfer from the organic to the aqueous phase, thus enhancing the depletion of DNAPL source zones compared to natural dissolution. This is achieved by promoting biological activity that reduces the contaminant's aqueous phase concentration. Although laboratory studies have demonstrated that high reaction rates are attainable by specialized microbial cultures in DNAPL source zones, field applications of the technology report lower reaction rates and prolonged remediation times. One possible explanation for this phenomenon is that the reaction rates are limited by the rate at which the contaminant partitions from the DNAPL to the aqueous phase. In such cases, slow mass transfer to the aqueous phase reduces the bioavailability of the contaminant and consequently decreases the potential source zone depletion enhancement. In this work, the effect of rate limited mass transfer on bio-enhanced dissolution of DNAPL chlorinated ethenes is investigated through a numerical study. A multi-phase, multi-component groundwater transport model is employed to simulate DNAPL mass depletion for a range of source zone scenarios. Rate limited mass transfer is modeled by a linear driving force model, employing a thermodynamic approach for the calculation of the DNAPL - water interfacial area. Metabolic reductive dechlorination is modeled by Monod kinetics, considering microbial growth and self-inhibition. The model was utilized to identify conditions in which mass transfer, rather than reaction, is the limiting process, as indicated by the bioavailability number. In such cases, reaction is slower than expected, and further increase in the reaction rate does not enhance mass depletion. Mass transfer rate limitations were shown to affect both dechlorination and microbial growth kinetics. The complex dynamics between mass transfer, DNAPL transport and distribution, and

  12. ANALYTICAL ASSESSMENT OF THE IMPACTS OF PARTIAL MASS DEPLETION IN DNAPL SOURCE ZONES (SAN FRANCISCO, CA)

    EPA Science Inventory

    Analytical solutions describing the time-dependent DNAPL source-zone mass and contaminant discharge rate are used as a flux-boundary condition in a semi-analytical contaminant transport model. These analytical solutions assume a power relationship between the flow-averaged sourc...

  13. ANALYTICAL ASSESSMENT OF THE IMPACTS OF PARTIAL MASS DEPLETION IN DNAPL SOURCE ZONES (SAN FRANCISCO, CA)

    EPA Science Inventory

    Analytical solutions describing the time-dependent DNAPL source-zone mass and contaminant discharge rate are used as a flux-boundary condition in a semi-analytical contaminant transport model. These analytical solutions assume a power relationship between the flow-averaged sourc...

  14. CONTAMINANT FLUX RESPONSES TO THERMAL TREATMENT OF DNAPL SOURCE ZONES (ABSTRACT ONLY)

    EPA Science Inventory

    Contaminant flux is being proposed as a metric to help elucidate the benefits of DNAPL source-zone remedial efforts. While it is clear that aggressive remediation technologies can rapidly remove DNAPL mass, experience has shown that complete removal is often not practicable. H...

  15. CONTAMINANT FLUX RESPONSES TO THERMAL TREATMENT OF DNAPL SOURCE ZONES (ABSTRACT ONLY)

    EPA Science Inventory

    Contaminant flux is being proposed as a metric to help elucidate the benefits of DNAPL source-zone remedial efforts. While it is clear that aggressive remediation technologies can rapidly remove DNAPL mass, experience has shown that complete removal is often not practicable. H...

  16. Changes in contaminant mass discharge from DNAPL source mass depletion: Evaluation at two field sites

    NASA Astrophysics Data System (ADS)

    Brooks, Michael C.; Wood, A. Lynn; Annable, Michael D.; Hatfield, Kirk; Cho, Jaehyun; Holbert, Charles; Rao, P. Suresh C.; Enfield, Carl G.; Lynch, Kira; Smith, Richard E.

    2008-11-01

    Changes in contaminant fluxes resulting from aggressive remediation of dense nonaqueous phase liquid (DNAPL) source zone were investigated at two sites, one at Hill Air Force Base (AFB), Utah, and the other at Ft. Lewis Military Reservation, Washington. Passive Flux Meters (PFM) and a variation of the Integral Pumping Test (IPT) were used to measure fluxes in ten wells installed along a transect down-gradient of the trichloroethylene (TCE) source zone, and perpendicular to the mean groundwater flow direction. At both sites, groundwater and contaminant fluxes were measured before and after the source-zone treatment. The measured contaminant fluxes ( J; ML - 2 T - 1 ) were integrated across the well transect to estimate contaminant mass discharge ( MD; MT - 1 ) from the source zone. Estimated MD before source treatment, based on both PFM and IPT methods, were ~ 76 g/day for TCE at the Hill AFB site; and ~ 640 g/day for TCE, and ~ 206 g/day for cis-dichloroethylene (DCE) at the Ft. Lewis site. TCE flux measurements made 1 year after source treatment at the Hill AFB site decreased to ~ 5 g/day. On the other hand, increased fluxes of DCE, a degradation byproduct of TCE, in tests subsequent to remediation at the Hill AFB site suggest enhanced microbial degradation after surfactant flooding. At the Ft. Lewis site, TCE mass discharge rates subsequent to remediation decreased to ~ 3 g/day for TCE and ~ 3 g/day for DCE ~ 1.8 years after remediation. At both field sites, PFM and IPT approaches provided comparable results for contaminant mass discharge rates, and show significant reductions (> 90%) in TCE mass discharge as a result of DNAPL mass depletion from the source zone.

  17. Changes in contaminant mass discharge from DNAPL source mass depletion: evaluation at two field sites.

    PubMed

    Brooks, Michael C; Wood, A Lynn; Annable, Michael D; Hatfield, Kirk; Cho, Jaehyun; Holbert, Charles; Rao, P Suresh C; Enfield, Carl G; Lynch, Kira; Smith, Richard E

    2008-11-14

    Changes in contaminant fluxes resulting from aggressive remediation of dense nonaqueous phase liquid (DNAPL) source zone were investigated at two sites, one at Hill Air Force Base (AFB), Utah, and the other at Ft. Lewis Military Reservation, Washington. Passive Flux Meters (PFM) and a variation of the Integral Pumping Test (IPT) were used to measure fluxes in ten wells installed along a transect down-gradient of the trichloroethylene (TCE) source zone, and perpendicular to the mean groundwater flow direction. At both sites, groundwater and contaminant fluxes were measured before and after the source-zone treatment. The measured contaminant fluxes (J; ML(-2)T(-1)) were integrated across the well transect to estimate contaminant mass discharge (M(D); MT(-1)) from the source zone. Estimated M(D) before source treatment, based on both PFM and IPT methods, were approximately 76 g/day for TCE at the Hill AFB site; and approximately 640 g/day for TCE, and approximately 206 g/day for cis-dichloroethylene (DCE) at the Ft. Lewis site. TCE flux measurements made 1 year after source treatment at the Hill AFB site decreased to approximately 5 g/day. On the other hand, increased fluxes of DCE, a degradation byproduct of TCE, in tests subsequent to remediation at the Hill AFB site suggest enhanced microbial degradation after surfactant flooding. At the Ft. Lewis site, TCE mass discharge rates subsequent to remediation decreased to approximately 3 g/day for TCE and approximately 3 g/day for DCE approximately 1.8 years after remediation. At both field sites, PFM and IPT approaches provided comparable results for contaminant mass discharge rates, and show significant reductions (>90%) in TCE mass discharge as a result of DNAPL mass depletion from the source zone.

  18. MEASUREMENTS OF CAPILLARY PRESSURE-SATURATION RELATIONSHIPS AND DNAPL DISTRIBUTION IN SILICA SANDS USING LIGHT TRANSMISSION VISUALIZATION

    EPA Science Inventory

    This study is a part of an ongoing research project that aims at assessing the environmental benefits of partial DNAPL removal. The laboratory part of the research project is to examine the functional relationship between DNAPL (modeled by PCE) architecture, mass removal and cont...

  19. MEASUREMENTS OF CAPILLARY PRESSURE-SATURATION RELATIONSHIPS AND DNAPL DISTRIBUTION IN SILICA SANDS USING LIGHT TRANSMISSION VISUALIZATION

    EPA Science Inventory

    This study is a part of an ongoing research project that aims at assessing the environmental benefits of partial DNAPL removal. The laboratory part of the research project is to examine the functional relationship between DNAPL (modeled by PCE) architecture, mass removal and cont...

  20. Impacts of DNAPL Source Treatment: Experimental and Modeling Assessment of the Benefits of Partial DNAPL Source Removal

    DTIC Science & Technology

    2009-09-01

    the surfactant flood, TCE levels were reduced significantly with only minimal local hot spots remaining in the transect (further details can be found...transition from wet spring conditions to a lower water table position observed in the summer. This is supported by the measured groundwater elevations...likely to identify interwell “ hot spots” and thus provide a more representative measure of mass discharge. It is estimated that the PITT removed only

  1. Changes in Contaminant Mass Discharge from DNAPL Source Mass Depletion: Evaluation at Two Field Sites

    EPA Science Inventory

    Changes in contaminant fluxes resulting from aggressive remediation of dense nonaqueous phase liquid (DNAPL) source zone were investigated at two sites, one at Hill Air Force Base (AFB), Utah, and the other at Ft. Lewis Military Reservation, WA. Passive Flux Meters (PFM) and a va...

  2. Changes in Contaminant Mass Discharge from DNAPL Source Mass Depletion: Evaluation at Two Field Sites

    EPA Science Inventory

    Changes in contaminant fluxes resulting from aggressive remediation of dense nonaqueous phase liquid (DNAPL) source zone were investigated at two sites, one at Hill Air Force Base (AFB), Utah, and the other at Ft. Lewis Military Reservation, WA. Passive Flux Meters (PFM) and a va...

  3. Long-term mass transfer and mixing-controlled reactions of a DNAPL plume from persistent residuals

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Illangasekare, Tissa H.; Kitanidis, Peter K.

    2014-02-01

    Understanding and being able to predict the long-term behavior of DNAPL (i.e., PCE and TCE) residuals after active remediation has ceased have become increasingly important as attention at many sites turns from aggressive remediation to monitored natural attenuation and long-term stewardship. However, plume behavior due to mass loading and reactions during these later phases is less studied as they involve large spatial and temporal scales. We apply both theoretical analysis and pore-scale simulations to investigate mass transfer from DNAPL residuals and subsequent reactions within the generated plume, and, in particular, to show the differences between early- and late-time behaviors of the plume. In the zone of entry of the DNAPL entrapment zone where the concentration boundary layer in the flowing groundwater has not fully developed, the pore-scale simulations confirm the past findings based on laboratory studies that the mass transfer increases as a power-law function of the Peclét number, and is enhanced due to reactions in the plume. Away from the entry zone and further down gradient, the long-term reactions are limited by the available additive and mixing in the porous medium, thereby behave considerably differently from the entry zone. For the reaction between the contaminant and an additive with intrinsic second-order bimolecular kinetics, the late-time reaction demonstrates a first-order decay macroscopically with respect to the mass of the limiting additive, not with respect to that of the contaminant. The late-time decay rate only depends on the intrinsic reaction rate and the solubility of the entrapped DNAPL. At the intermediate time, the additive decays exponentially with the square of time (t2), instead of time (t). Moreover, the intermediate decay rate also depends on the initial conditions, the spatial distribution of DNAPL residuals, and the effective dispersion coefficient.

  4. A consistent framework to predict mass fluxes and depletion times for DNAPL contaminations in heterogeneous aquifers under uncertainty

    NASA Astrophysics Data System (ADS)

    Koch, Jonas; Nowak, Wolfgang

    2013-04-01

    At many hazardous waste sites and accidental spills, dense non-aqueous phase liquids (DNAPLs) such as TCE, PCE, or TCA have been released into the subsurface. Once a DNAPL is released into the subsurface, it serves as persistent source of dissolved-phase contamination. In chronological order, the DNAPL migrates through the porous medium and penetrates the aquifer, it forms a complex pattern of immobile DNAPL saturation, it dissolves into the groundwater and forms a contaminant plume, and it slowly depletes and bio-degrades in the long-term. In industrial countries the number of such contaminated sites is tremendously high to the point that a ranking from most risky to least risky is advisable. Such a ranking helps to decide whether a site needs to be remediated or may be left to natural attenuation. Both the ranking and the designing of proper remediation or monitoring strategies require a good understanding of the relevant physical processes and their inherent uncertainty. To this end, we conceptualize a probabilistic simulation framework that estimates probability density functions of mass discharge, source depletion time, and critical concentration values at crucial target locations. Furthermore, it supports the inference of contaminant source architectures from arbitrary site data. As an essential novelty, the mutual dependencies of the key parameters and interacting physical processes are taken into account throughout the whole simulation. In an uncertain and heterogeneous subsurface setting, we identify three key parameter fields: the local velocities, the hydraulic permeabilities and the DNAPL phase saturations. Obviously, these parameters depend on each other during DNAPL infiltration, dissolution and depletion. In order to highlight the importance of these mutual dependencies and interactions, we present results of several model set ups where we vary the physical and stochastic dependencies of the input parameters and simulated processes. Under these

  5. Consistent Simulation Framework for Efficient Mass Discharge and Source Depletion Time Predictions of DNAPL Contaminants in Heterogeneous Aquifers Under Uncertainty

    NASA Astrophysics Data System (ADS)

    Nowak, W.; Koch, J.

    2014-12-01

    Predicting DNAPL fate and transport in heterogeneous aquifers is challenging and subject to an uncertainty that needs to be quantified. Models for this task needs to be equipped with an accurate source zone description, i.e., the distribution of mass of all partitioning phases (DNAPL, water, and soil) in all possible states ((im)mobile, dissolved, and sorbed), mass-transfer algorithms, and the simulation of transport processes in the groundwater. Such detailed models tend to be computationally cumbersome when used for uncertainty quantification. Therefore, a selective choice of the relevant model states, processes, and scales are both sensitive and indispensable. We investigate the questions: what is a meaningful level of model complexity and how to obtain an efficient model framework that is still physically and statistically consistent. In our proposed model, aquifer parameters and the contaminant source architecture are conceptualized jointly as random space functions. The governing processes are simulated in a three-dimensional, highly-resolved, stochastic, and coupled model that can predict probability density functions of mass discharge and source depletion times. We apply a stochastic percolation approach as an emulator to simulate the contaminant source formation, a random walk particle tracking method to simulate DNAPL dissolution and solute transport within the aqueous phase, and a quasi-steady-state approach to solve for DNAPL depletion times. Using this novel model framework, we test whether and to which degree the desired model predictions are sensitive to simplifications often found in the literature. With this we identify that aquifer heterogeneity, groundwater flow irregularity, uncertain and physically-based contaminant source zones, and their mutual interlinkages are indispensable components of a sound model framework.

  6. Designing, Assessing, and Demonstrating Sustainable Bioaugmentation for Treatment of DNAPL Sources in Fractured Bedrock

    DTIC Science & Technology

    2017-03-27

    donor and nutrient delivery) was followed by a 10-month rebound period. While enhanced dissolution of the DNAPL sources was observed in both the...shallow and deep fractures intervals, a greater extent of DNAPL mass removal (approximately 100%) was observed in the shallow fracture zone, while only 45...no increases in chlorinated ethenes or ethene was observed in the shallow zone during the 10-month rebound period, data suggest the sum of

  7. Architecture, persistence and dissolution of a 20 to 45 year old trichloroethene DNAPL source zone

    NASA Astrophysics Data System (ADS)

    Rivett, Michael O.; Dearden, Rachel A.; Wealthall, Gary P.

    2014-12-01

    laboratory data. DNAPL dissolution yielded heterogeneous dissolved-phase plumes of TCE and its dechlorination products that exhibited orders of magnitude local concentration variation. TCE solubility concentrations were relatively localised, but coincident with high saturation DNAPL lens source areas. Biotic dechlorination in the source zone area, however, caused cDCE to be the dominant dissolved-phase plume. The conservative tracer test usefully confirmed the continuity of a permeable gravel unit at depth through the source zone. Although this unit offered significant opportunity for DNAPL bypassing and decreased timeframes for dechlorination, it still transmitted a significant proportion of the contaminant flux. This was attributed to dissolution of DNAPL-mudstone aquitard associated sources at the base of the continuous gravel as well as contaminated groundwater from surrounding less permeable sand and gravel horizons draining into this permeable conduit. The cell extraction well provided an integrated metric of source zone dissolution yielding a mean concentration of around 45% TCE solubility (taking into account dechlorination) that was equivalent to a DNAPL mass removal rate of 0.4 tonnes per annum over a 16 m2 cell cross sectional area of flow. This is a significant flux considering the source age and observed occurrence of much of the source mass within discrete lenses/pools. We advocate the need for further detailed field-scale studies on old DNAPL source zones that better resolve persistent pool/lens features and are of prolonged duration to assess the ageing of source zones. Such studies would further underpin the application of more surgical remediation technologies.

  8. Natural and man-made controls on the performance of DNAPL-pump-and-treat systems -- A comparative case study

    SciTech Connect

    Losonsky, G.; Landry, G.R.; Valentine, R.M.

    1996-12-31

    Although the recovery of dense non-aqueous liquids (DNAPLs) using pump-and-treat technology generally does not achieve regulatory cleanup criteria for dissolved phase concentrations in groundwater, the technology is commonly used to achieve two alternate goals--to recover DNAPL mass and to prevent or slow down the spread of DNAPL pools. Both the physico-chemical characteristics of the DNAPL and the hydrogeologic characteristics of the subsurface determine the effectiveness of DNAPL pump-and-treat systems in achieving these goals. Physico-chemical characteristics include density, viscosity, interfacial tension, and solubility. Some of these parameters can change naturally over time, and some can be manipulated using enhanced recovery agents, such as steam or surfactants. Hydrogeologic characteristics include hydraulic conductivity, anisotropy, heterogeneity, fracture porosity, capillary pressure, and hydraulic gradients. The operation of a pump-and-treat system necessarily affects the hydraulic gradients and capillary pressures governing subsurface fluid flow at a DNAPL site. Both naturally occurring low-permeability zones and man-made, compacted clay liners influence DNAPL migration. The performance of a DNAPL pump-and-treat system changes with time. High mass removal may occur early in the operation of such a system, whereas DNAPL migration away from the recovery wells or even out of the pumped hydrostratigraphic unit may dominate later stages of operation of the system. A comparison of several interim corrective measures (ICM) pump-and-treat systems at a site in the Gulf Coast illustrates the combined effects of both natural and man-made controls on the performance of the DNAPL recovery systems.

  9. A multi-objective optimization framework for surfactant-enhanced remediation of DNAPL contaminations

    NASA Astrophysics Data System (ADS)

    Schaerlaekens, Jan; Mertens, Jan; Van Linden, Jan; Vermeiren, Gert; Carmeliet, Jan; Feyen, Jan

    2006-08-01

    The occurrence of Dense Non-Aqueous Phase Liquid (DNAPL) contaminations in the subsurface is a threat for drinkwater resources in the western world. Surfactant-Enhanced Aquifer Remediation (SEAR) is widely considered as one of the most promising techniques to remediate DNAPL contaminations in-situ, be it with considerable additional costs compared to classical pump-and-treat remediations. A cost-effective design of the remediation set-up is therefore essential. In this work, a pilot SEAR test is executed at a DNAPL contaminated site in Belgium in order to collect data for the calibration of a multi-phase multi-component model. The calibrated model is used to assess a series of scenario-analyses for the full-scale remediation of the site. The remediation variables that were varied were the injection and extraction rate, the injection and extraction duration, and the surfactant injection concentrations. A constrained multi-objective optimization of the model was applied to obtain a Pareto set of optimal remediation strategies with different weights for the two objectives of the remediation: (i) the maximal removal of DNAPL and (ii) a total minimal cost. These Pareto curves can help decision makers to select an optimal remediation strategy in terms of cost and remediation efficiency. The Pareto front shows a considerable trade-off between the total remediation cost and the removed DNAPL mass.

  10. ALCOHOL FLUSHING FOR REMOVING DNAPL'S FROM CLAY AND SAND LAYERED AQUIFER SYSTEMS

    SciTech Connect

    N.J. Hayden; P. Padgett; C. Farrell; J. Diebold; X. Zhou; M. Hood

    1999-08-01

    Alcohol flushing, also called cosolvent flushing, is a relatively new in-situ remediation technology that shows promise for removing organic solvents from the soil and groundwater. Soil and groundwater contamination from organic solvents and petroleum products is one of the most serious and widespread environmental problems of our time. Most of the DOE facilities and inactive sites are experiencing soil and groundwater contamination from organic solvents. These water immiscible solvents have entered the subsurface from leaking underground storage tanks and piping, and from past waste handling and disposal practices such as leaking lagoons, holding ponds and landfills. In many cases, they have traveled hundreds of feet down into the saturated zone. If left in the soil, these chemicals may pose a significant environmental and human health risk. Alcohol flushing has potential for application to spilled solvents located deep within the saturated zone which are difficult if not impossible to remove by current remediation strategies, thus, greatly expediting restoration time, reducing total remediation cost and reducing risk.

  11. Can Pickering emulsion formation aid the removal of creosote DNAPL from porous media?

    PubMed

    Torres, Luis; Iturbe, Rosario; Snowden, M J; Chowdhry, Babur; Leharne, Stephen

    2008-03-01

    The purpose of this investigation was to examine the proposition that creosote, emplaced in an initially water saturated porous system, can be removed from the system through Pickering emulsion formation. Pickering emulsions are dispersions of two immiscible fluids in which coalescence of the dispersed phase droplets is hindered by the presence of colloidal particles adsorbed at the interface between the two immiscible fluid phases. Particle trapping is strongly favoured when the wetting properties of the particles are intermediate between strong water wetting and strong oil wetting. In this investigation the necessary chemical conditions for the formation of physically stable creosote-in-water emulsions protected against coalescence by bentonite particles were examined. It was established that physically stable emulsions could be formed through the judicious addition of small amounts of sodium chloride and the surfactant cetyl-trimethylammonium bromide. The stability of the emulsions was initially established by visual inspection. However, experimental determinations of emulsion stability were also undertaken by use of oscillatory rheology. Measurements of the elastic and viscous responses to shear indicated that physically stable emulsions were obtained when the viscoelastic systems showed a predominantly elastic response to shearing. Once the conditions were established for the formation of physically stable emulsions a "proof-of-concept" chromatographic experiment was carried out which showed that creosote could be successfully removed from a saturated model porous system.

  12. Modeling field-scale cosolvent flooding for DNAPL source zone remediation.

    PubMed

    Liang, Hailian; Falta, Ronald W

    2008-02-19

    A three-dimensional, compositional, multiphase flow simulator was used to model a field-scale test of DNAPL removal by cosolvent flooding. The DNAPL at this site was tetrachloroethylene (PCE), and the flooding solution was an ethanol/water mixture, with up to 95% ethanol. The numerical model, UTCHEM accounts for the equilibrium phase behavior and multiphase flow of a ternary ethanol-PCE-water system. Simulations of enhanced cosolvent flooding using a kinetic interphase mass transfer approach show that when a very high concentration of alcohol is injected, the DNAPL/water/alcohol mixture forms a single phase and local mass transfer limitations become irrelevant. The field simulations were carried out in three steps. At the first level, a simple uncalibrated layered model is developed. This model is capable of roughly reproducing the production well concentrations of alcohol, but not of PCE. A more refined (but uncalibrated) permeability model is able to accurately simulate the breakthrough concentrations of injected alcohol from the production wells, but is unable to accurately predict the PCE removal. The final model uses a calibration of the initial PCE distribution to get good matches with the PCE effluent curves from the extraction wells. It is evident that the effectiveness of DNAPL source zone remediation is mainly affected by characteristics of the spatial heterogeneity of porous media and the variable (and unknown) DNAPL distribution. The inherent uncertainty in the DNAPL distribution at real field sites means that some form of calibration of the initial contaminant distribution will almost always be required to match contaminant effluent breakthrough curves.

  13. DNAPL Surface Chemistry: Its Impact on DNAPL Distribution in the Vadose Zone and its Manipulation to Enhance Remediation

    SciTech Connect

    Suan Power; Stefan Grimberg; Miles Denham

    2003-06-16

    The remediation of DNAPLs in subsurface environments is often limited by the heterogeneous distribution of the organic fluid. The fraction of DNAPL that is in the high conductivity regions of the subsurface can often be recovered relatively easily, although DNAPL in lower conductivity regions is much more difficult to extract, either through direct pumping or remediation measures based on interface mass transfer. The distribution of DNAPL within the vadose zone is affected by a complex interplay of heterogeneities in the porous matrix and the interfacial properties defining the interactions among all fluid and solid phases. Decreasing the interfacial tension between a DNAPL and water in the vadose zone could change the spreading of the DNAPL, thereby increase the surface area for mass transfer and the effectiveness of soil vapor extraction remediation.

  14. Coupling Surfactants/Cosolvents with Oxidants: Effects on Site Characterization and DNAPL Remediation

    NASA Astrophysics Data System (ADS)

    Dugan, P. J.; Siegrist, R. L.; Crimi, M. L.

    2004-12-01

    uncertainty, and assessing remediation efficiency is difficult. Effluent concentrations can be monitored in the extraction fluid during surfactant/cosolvent flushing, as an independent measure of mass removed. However, a challenge with ISCO in terms of performance assessment is that there is no way to directly measure mass destroyed, except through post-remediation characterization (i.e., PTTs or soil cores). Column and 2-D cell studies were conducted to investigate removal of DNAPL with surfactant/cosolvent flushing coupled with ISCO using the oxidant potassium permanganate. Partitioning and non-partitioning tracers were used in the pre- and post-remediation studies to investigate the effect of these remedial techniques on the viability of PTT.

  15. Multi objective optimization of the setup of a surfactant-enhanced DNAPL remediation.

    PubMed

    Schaerlaekens, Jan; Carmeliet, Jan; Feyen, Jan

    2005-04-01

    Surfactant-enhanced aquifer remediation (SEAR) is widely considered a promising technique to remediate dense nonaqueous phase liquid (DNAPL) contaminations in-situ. The costs of a SEAR remediation are important and depend mostly on the setup of the remediation. Costs can be associated with the installation of injection and extraction wells, the required time of the remediation (and thus labor costs, lease of installations, and energy), the extracted water volume (the purification of the extracted water), and the injected surfactant amount. A cost-effective design of the remediation setup allows an optimal use of resources. In this work, a SEAR remediation was simulated for a hypothetical typical DNAPL contamination. A constrained multi-objective optimization of the model was applied to obtain a Pareto set of optimal remediation strategies with different weights for the two objectives of the remediation: (i) the maximal removal of DNAPL mass (ii) with a minimal total cost. A relatively sharp Pareto front was found, showing a considerable tradeoff between DNAPL removal and total remediation costs. These Pareto curves can help decision makers select an optimal remediation strategy in terms of cost and remediation efficiency depending on external constraints such as the available budget and obligatory remediation goals.

  16. Numerical and experimental investigation of DNAPL removal mechanisms in a layered porous medium by means of soil vapor extraction.

    PubMed

    Yoon, Hongkyu; Oostrom, Mart; Wietsma, Thomas W; Werth, Charles J; Valocchi, Albert J

    2009-10-13

    The purpose of this work is to identify the mechanisms that govern the removal of carbon tetrachloride (CT) during soil vapor extraction (SVE) by comparing numerical and analytical model simulations with a detailed data set from a well-defined intermediate-scale flow cell experiment. The flow cell was packed with a fine-grained sand layer embedded in a coarse-grained sand matrix. A total of 499 mL CT was injected at the top of the flow cell and allowed to redistribute in the variably saturated system. A dual-energy gamma radiation system was used to determine the initial NAPL saturation profile in the fine-grained sand layer. Gas concentrations at the outlet of the flow cell and 15 sampling ports inside the flow cell were measured during subsequent CT removal using SVE. Results show that CT mass was removed quickly in coarse-grained sand, followed by a slow removal from the fine-grained sand layer. Consequently, effluent gas concentrations decreased quickly at first, and then started to decrease gradually, resulting in long-term tailing. The long-term tailing was mainly due to diffusion from the fine-grained sand layer to the coarse-grained sand zone. An analytical solution for a one-dimensional advection and a first-order mass transfer model matched the tailing well with two fitting parameters. Given detailed knowledge of the permeability field and initial CT distribution, we were also able to predict the effluent concentration tailing and gas concentration profiles at sampling ports using a numerical simulator assuming equilibrium CT evaporation. The numerical model predictions were accurate within the uncertainty of independently measured or literature derived parameters. This study demonstrates that proper numerical modeling of CT removal through SVE can be achieved using equilibrium evaporation of NAPL if detailed fine-scale knowledge of the CT distribution and physical heterogeneity is incorporated into the model. However, CT removal could also be fit by a

  17. Numerical and experimental investigation of DNAPL removal mechanisms in a layered porous medium by means of soil vapor extraction

    SciTech Connect

    Yoon, Hongkyu; Oostrom, Martinus; Wietsma, Thomas W.; Werth, Charles J.; Valocchi, Albert J.

    2009-10-13

    The purpose of this work is to identify the mechanisms that govern the removal of carbon tetrachloride (CT) during soil vapor extraction (SVE) by comparing multiphase flow simulations with a detailed data set from a well-defined two-dimensional flow cell experiment. The flow cell was packed with two sandy soils including an embedded fine-grained sand layer. Gas concentrations at the outlet of the flow cell and 15 sampling ports inside the flow cell were measured during SVE. A dual-energy gamma radiation system was used to measure an initial NAPL saturation profile in a fine-grained sand layer. Imaging result from a dual-energy gamma radiation system with dyed CT mark along CT migration was used to construct the distribution of initial NAPL saturation in the flow cell for input to numerical simulations. Gas concentration results and photographs during SVE were compared to simulation results using a continuum-based multiphase flow simulator, STOMP (Subsurface Transport Over Multiple Phases). The measured effluent gas concentration decreased quickly at first, and then started to decrease gradually, resulting in long-term tailing. CT mass was removed quickly in coarse sand, followed by a slow removal from the fine-grained sand layer. An analytical solution for a one-dimensional advection and first-order volatilization model matched the tailing well with two fitting parameters. However, given detailed knowledge of the permeability field and initial NAPL distribution, we can predict the tailing and gas concentration profiles at sampling ports using equilibrium NAPL volatilization. NAPL flow occurs in the presence of free NAPL, and must be accounted for to accurately predict NAPL removal during the SVE experiment. The model prediction was accurate within the uncertainty of the measured or literature derived parameters (i.e., dispersivity and soil parameters). This study provides insights into the physical mechanisms of NAPL removal from a low permeability zone, and use of

  18. Coupling Surfactant Flushing and Bioaugmentation for PCE-DNAPL Source Zone Treatment

    NASA Astrophysics Data System (ADS)

    Cápiro, N. L.; Granbery, E. K.; Amos, B. K.; Löffler, F. E.; Pennell, K. D.

    2008-12-01

    Enhanced solubilization flushing using a biodegradable surfactant (Tween 80) was combined with bioaugmentation to initiate microbial reductive dechlorination and detoxify residual tetrachloroethene (PCE)- dense nonaqueous phase liquid (DNAPL). Dechlorination activity, spatial distribution of Dehalococcoides spp., and down-gradient plume development were monitored in a 2-D aquifer cell equipped with eighteen sampling ports. Saturation distributions of the PCE-DNAPL source zone were quantified using a light transmission system to determine the ganglia-to-pool (GTP) volume ratio, which was approximately 1.5 (i.e., 60% ganglia and 40% pools) prior to surfactant flushing. Flushing with three pore volumes (PVs) of 4% (w/w) Tween 80 solution recovered approximately 55% of the original PCE mass and reduced PCE effluent concentration from saturation (200 mg/L) to less than 50 mg/L. Following the introduction of reduced basal salts medium amended with 10 mM lactate, nine side ports located upstream and within the initial PCE- DNAPL source zone were augmented with Bio-Dechlor INOCULUM (BDI), a PCE-to-ethene dechlorinating consortium. Flux-averaged measurements of aqueous effluent samples revealed the conversion of PCE to cis-dichloroethene (DCE) with minimal lag time (7 days, approx. 1 PV), and vinyl chloride and ethene were detected within 10 PVs after bioaugmentation. Quantitative real-time PCR (qPCR) targeting Dehalococcoides spp. demonstrated growth once aqueous PCE concentrations decreased below inhibitory levels (~540 mM), with significant growth (2 to 4-orders of magnitude) near the remaining source zone. These results demonstrate the successful colonization of a pool-dominated (NAPL saturation >0.13) PCE- DNAPL source zone by a dechlorinating consortium following partial mass removal, and the potential for locally bioenhanced DNAPL dissolution.

  19. The Impact of DNAPL Source-Zone Architecture on Contaminant Mass Flux and Plume Evolution in Heterogeneous Porous Media

    DTIC Science & Technology

    2013-08-01

    systems is critical to accurately assess the human-health risks associated with sites contaminated by chlorinated solvents, and to design effective...and complex behavior, chlorinated solvents continue to pose a significant risk to human health and the environment. A clear understanding of the...mass-transfer and mass-removal behavior of chlorinated solvents in subsurface systems is critical to accurately assess the human-health risks associated

  20. X-231A demonstration of in-situ remediation of DNAPL compounds in low permeability media by soil fracturing with thermally enhanced mass recovery or reactive barrier destruction

    SciTech Connect

    Siegrist, R.L. |; Lowe, K.S.; Murdoch, L.D. |; Slack, W.W.; Houk, T.C.

    1998-03-01

    The overall goal of the program of activities is to demonstrate robust and cost-effective technologies for in situ remediation of DNAPL compounds in low permeability media (LPM), including adaptations and enhancements of conventional technologies to achieve improved performance for DNAPLs in LPM. The technologies sought should be potential for application at simple, small sites (e.g., gasoline underground storage tanks) as well as at complex, larger sites (e.g., DOE land treatment units). The technologies involved in the X-231A demonstration at Portsmouth Gaseous Diffusion Plant (PORTS) utilized subsurface manipulation of the LPM through soil fracturing with thermally enhanced mass recovery or horizontal barrier in place destruction. To enable field evaluation of these approaches, a set of four test cells was established at the X-231A land treatment unit at the DOE PORTS plant in August 1996 and a series of demonstration field activities occurred through December 1997. The principal objectives of the PORTS X-231A demonstration were to: determine and compare the operational features of hydraulic fractures as an enabling technology for steam and hot air enhanced soil vapor extraction and mass recovery, in situ interception and reductive destruction by zero valent iron, and in situ interception and oxidative destruction by potassium permanganate; determine the interaction of the delivered agents with the LPM matrix adjacent to the fracture and within the fractured zone and assess the beneficial modifications to the transport and/or reaction properties of the LPM deposit; and determine the remediation efficiency achieved by each of the technology strategies.

  1. DNAPL Managements Overview

    DTIC Science & Technology

    2007-04-01

    case studies where MCLs were achieved throughout the DNAPL source zone. Another part of the challenge is that applying source-zone remediation...technologies without well-defined project objectives will likely lead to excessive costs, risks, or failures. Two case studies are presented to highlight... case studies where MCLs were achieved throughout the DNAPL source zone. Another part of the challenge is that applying source-zone remediation

  2. THE MEASUREMENT AND USE OF CONTAMINANT FLUX FOR PERFORMANCE ASSESSMENT OF DNAPL REMEDIATION

    EPA Science Inventory

    A review is presented of both mass flux as a DNAPL remedial performance metric and reduction in mass flux as a remedial performance objective at one or more control planes down gradient of DNAPL source areas. The use of mass flux to assess remedial performance has been proposed ...

  3. Biodegradation of Chlorinated Solvents: Reactions near DNAPL and Enzyme Function

    SciTech Connect

    McCarty, Perry L.; Spormann, Alfred M.; Criddle, Craig S.

    2001-06-01

    The anaerobic biodegradation of chlorinated solvents is of great interest both for natural attenuation and for engineered remediation of these hazardous contaminants in groundwater. Compounds to be studied are carbon tetrachloride (CT) and the chlorinated ethenes, tetrachloroethene (PCE), trichloroethene (TCE) cis-1,2-dichloroethene (cDCE), and vinyl chloride (VC). The chlorinated solvents often are present as dense non-aqueous-phase liquids (DNAPLs), which are difficult to remove. Biodegradation of DNAPLs was previously thought not possible because of toxicity, but recent evidence indicates that under the right conditions, biodegradation is possible. Anaerobic biodegradation of DNAPLs is the major subject of this research. The specific objectives of this multi-investigator effort are: (1) Evaluate the potential for chlorinated solvent biodegradation near DNAPLs, (2) Provide a molecular understanding of the biological mechanisms involved, (3) Determine cellular components involved in carbon tetrachloride transformation by Pseudomonas stutzeri strain KC without chloroform formation.

  4. Biodegradation of Chlorinated Solvents: Reactions near DNAPL and Enzyme Function

    SciTech Connect

    McCarty, Perry L.; Spormann, Alfred M.; Criddle, Craig S.

    2002-06-01

    The anaerobic biodegradation of chlorinated solvents is of great interest both for natural attenuation and for engineered remediation of these hazardous contaminants in groundwater. Compounds to be studied are carbon tetrachloride (CT) and the chlorinated ethenes, tetrachloroethene (PCE), trichloroethene (TCE) cis-1,2-dichloroethene (cDCE), and vinyl chloride (VC). The chlorinated solvents often are present as dense non-aqueous-phase liquids (DNAPLs), which are difficult to remove. Biodegradation of DNAPLs was previously thought not possible because of toxicity, but recent evidence indicates that under the right conditions, biodegradation is possible. Anaerobic biodegradation of DNAPLs is the major subject of this research. The specific objectives of this multi-investigator effort are: (1) Evaluate the potential for chlorinated solvent biodegradation near DNAPLs, (2) Provide a molecular understanding of the biological mechanisms involved, (3) Determine cellular components involved in carbon tetrachloride transformation by Pseudomonas stutzeri strain KC without chloroform formation.

  5. Biodegradation of Chlorinated Solvents: Reactions near DNAPL and Enzyme Function

    SciTech Connect

    McCarty, Perry L.; Spormann, Alfred M.; Criddle, Craig S.

    2003-06-01

    The anaerobic biodegradation of chlorinated solvents is of great interest both for natural attenuation and for engineered remediation of these hazardous contaminants in groundwater. Compounds to be studied are carbon tetrachloride (CT) and the chlorinated ethenes, tetrachloroethene (PCE), trichloroethene (TCE) cis-1,2-dichloroethene (cDCE), and vinyl chloride (VC). The chlorinated solvents often are present as dense non-aqueous-phase liquids (DNAPLs), which are difficult to remove. Biodegradation of DNAPLs was previously thought not possible because of toxicity, but recent evidence indicates that under the right conditions, biodegradation is possible. Anaerobic biodegradation of DNAPLs is the major subject of this research. The specific objectives of this multi-investigator effort are: (1) Evaluate the potential for chlorinated solvent biodegradation near DNAPLs, (2) Provide a molecular understanding of the biological mechanisms involved, (3) Determine cellular components involved in carbon tetrachloride transformation by Pseudomonas stutzeri strain KC without chloroform formation.

  6. Numerical simulation of DNAPL emissions and remediation in a fractured dolomitic aquifer.

    PubMed

    McLaren, Robert G; Sudicky, Edward A; Park, Young-Jin; Illman, Walter A

    2012-08-01

    This study presents a numerical model of a large aqueous phase plume of a mixture of chlorinated solvents that has penetrated the fractured dolomitic bedrock near Smithville, Ontario, Canada several decades ago which, since 1989 has been hydraulically controlled by a pump-and-treat remediation system. A multiphase compositional model CompFlow is first applied to simulate the migration of DNAPLs in a discretely fractured porous medium with hydrostratigraphy representing the Smithville site. Results from CompFlow are used to estimate the pure-phase DNAPL distribution in the discrete fractures and rock matrix. Next, CompFlow results are employed to define the source term for a regional-scale transport simulation using HydroGeoSphere (HGS) by treating the layered, fractured dolomitic rocks as an equivalent porous continuum. Transport simulations are conducted both prior to and after the operation of the pump-and-treat system. Results reveal that considerable agreement with the observed mass removal data and TCE plume can be achieved by modifying the composition of the DNAPL source and by reducing the hydraulic conductivity (K) in the source zone region to account for preferential flow around it. Our transport model results support the conceptual model of TCE contamination which posits a mixed source (2 to 4%) of DNAPL with limited contact with actively flowing groundwater that is undergoing equilibrium dissolution. Model results also reveal that the pump-and-treat system has neither been effective in stabilizing the plume nor removing a significant amount of contaminant mass, but that the stability of the plume is instead due to first-order degradation. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

  7. Characterizing Long-term Contaminant Mass Discharge and the Relationship Between Reductions in Discharge and Reductions in Mass for DNAPL Source Areas

    PubMed Central

    Matthieu, D.E.; Carroll, K.C.; Mainhagu, J.; Morrison, C.; McMillan, A.; Russo, A.; Plaschke, M.

    2013-01-01

    The objective of this study was to characterize the temporal behavior of contaminant mass discharge, and the relationship between reductions in contaminant mass discharge and reductions in contaminant mass, for a very heterogeneous, highly contaminated source-zone field site. Trichloroethene is the primary contaminant of concern, and several lines of evidence indicate the presence of organic liquid in the subsurface. The site is undergoing groundwater extraction for source control, and contaminant mass discharge has been monitored since system startup. The results show a significant reduction in contaminant mass discharge with time, decreasing from approximately 1 to 0.15 kg/d. Two methods were used to estimate the mass of contaminant present in the source area at the initiation of the remediation project. One was based on a comparison of two sets of core data, collected 3.5 years apart, which suggests that a significant (~80%) reduction in aggregate sediment-phase TCE concentrations occurred between sampling events. The second method was based on fitting the temporal contaminant mass discharge data with a simple exponential source-depletion function. Relatively similar estimates, 784 and 993 kg, respectively, were obtained with the two methods. These data were used to characterize the relationship between reductions in contaminant mass discharge (CMDR) and reductions in contaminant mass (MR). The observed curvilinear relationship exhibits a reduction in contaminant mass discharge essentially immediately upon initiation of mass reduction. This behavior is consistent with a system wherein significant quantities of mass are present in hydraulically poorly accessible domains for which mass removal is influenced by rate-limited mass transfer. The results obtained from the present study are compared to those obtained from other field studies to evaluate the impact of system properties and conditions on mass-discharge and mass-removal behavior. The results indicated that

  8. Characterizing long-term contaminant mass discharge and the relationship between reductions in discharge and reductions in mass for DNAPL source areas

    NASA Astrophysics Data System (ADS)

    Brusseau, M. L.; Matthieu, D. E.; Carroll, K. C.; Mainhagu, J.; Morrison, C.; McMillan, A.; Russo, A.; Plaschke, M.

    2013-06-01

    The objective of this study was to characterize the temporal behavior of contaminant mass discharge, and the relationship between reductions in contaminant mass discharge and reductions in contaminant mass, for a very heterogeneous, highly contaminated source-zone field site. Trichloroethene is the primary contaminant of concern, and several lines of evidence indicate the presence of organic liquid in the subsurface. The site is undergoing groundwater extraction for source control, and contaminant mass discharge has been monitored since system startup. The results show a significant reduction in contaminant mass discharge with time, decreasing from approximately 1 to 0.15 kg/d over five years. Two methods were used to estimate the mass of contaminant present in the source area at the initiation of the remediation project. One was based on a comparison of two sets of core data, collected 3.5 years apart, which suggests that a significant (~ 80%) reduction in aggregate sediment-phase TCE concentrations occurred between sampling events. The second method was based on fitting the temporal contaminant mass discharge data with a simple exponential source-depletion function. Relatively similar estimates, 784 and 993 kg, respectively, were obtained with the two methods. These data were used to characterize the relationship between reductions in contaminant mass discharge (CMDR) and reductions in contaminant mass (MR). The observed curvilinear relationship exhibits a reduction in contaminant mass discharge essentially immediately upon the initiation of mass reduction. This behavior is consistent with a system wherein significant quantities of mass are present in hydraulically poorly accessible domains for which mass removal is influenced by rate-limited mass transfer. The results obtained from the present study are compared to those obtained from other field studies to evaluate the impact of system properties and conditions on mass-discharge and mass-removal behavior. The

  9. FLUX-BASED METHODS FOR DNAPL REMEDIATION DESIGN AND ASSESSMENT

    EPA Science Inventory

    One tool that has been investigated for use in DNAPL site characterization and remediation is mass flux (mass per unit area per unit time) and mass discharge (mass per unit time) measurements. These measurements, when collected across one or more control planes located down grad...

  10. FLUX-BASED METHODS FOR DNAPL REMEDIATION DESIGN AND ASSESSMENT

    EPA Science Inventory

    One tool that has been investigated for use in DNAPL site characterization and remediation is mass flux (mass per unit area per unit time) and mass discharge (mass per unit time) measurements. These measurements, when collected across one or more control planes located down grad...

  11. Comparison of Chlorinated Ethenes DNAPL Reductive Dechlorination by Indigenous and Evanite culture with Surfactant Tween-80

    NASA Astrophysics Data System (ADS)

    Kwon, S.; Hong, S.; Kim, R.; Kim, N.; Ahn, H.; Lee, S.; Kim, Y.

    2010-12-01

    Although many innovative technologies have been developed to enhance remediation of chlorinated ethenes(e.g. tetrachloroethene[PCE], trichloroethene[TCE])DNAPL source zones, they have been ineffective in reducing contaminant concentration to regulatory end points. Thus, combination of surfactant flushing process that removes significant contaminant mass with microbial reductive dechlorination, posttreatment "polishing step" to control the remaining DNAPL that may serve as a source of reducing equivalents and stimulate the dechlorinating bacterial communities may be an attractive remediation process alternatively. Microcosm studies were conducted to explore chlorinated ethenes, PCE/TCE of 3 ~ 30 mg/L dechlorination by indigenous microbial communities from TCE DNAPL source zones of Korea and Evanite culture in the presence of Tween-80 of 10 ~ 5,000 mg/L. In the microcosms for indigenous microbial communities, by-products(e.g. c-DCE, vinyl chloride) of reductive dechlorination of PCE/TCE were not detected. This results suggest dechlorinating bacteria might be not exist or high concentration of chlorinated ethenes inhibit activity of dechlorinating bacteria in indigenous microbial communities. But VFAs like acetate, methane and hydrogen gas from fermentation of Tween-80 were detected. So Tween-80 might estimated to serve as a source of reducing equivalents. To evaluate the dechlorinating ability of Evanite-culture, we added Evanite-culture to the microcosms for indigenous bacteria and monitored by-products of reductive dechlorination of PCE/TCE and VFAs and hydrogen gas.

  12. Adjoint Sensitivity Analysis of Push-Pull Partitioning Tracer Test Data for DNAPL Saturation Estimation

    NASA Astrophysics Data System (ADS)

    Tang, T.; Boroumand, A.; Abriola, L. M.; Miller, E. L.

    2013-12-01

    Characterization of dense non-aqueous phase liquid (DNAPL) source zones is a critical component for successful remediation of sites contaminated by chlorinated solvents. Although Push-Pull Tracer Tests (PPTTs) offer a promising approach for local in situ source zone characterization, non-equilibrium mass transfer effects and the spatial variability of saturation make their interpretation difficult. To better understand the dependence of well test data on these factors and as the basis for the estimation of the spatial DNAPL distribution, here we develop numerical methods based on the use of adjoint sensitivity mehtods to explore the sensitivity of PPTT observations to the distribution of DNAPL saturation. We examine the utility of the developed approach using three-dimensional hypothetical source zones containing heterogeneous DNAPL distributions. For model applications the flow fields are generated with MODFLOW and non-equilibrium tracer mass transfer is described by a linear driving force expression. Comprehensive modeling of partitioning tracer tests requires the solution of tracer mass balance equations in the aqueous and DNAPL phases. Consistent with this process coupling, the developed adjoint method introduces a vector of adjoint variables to formulate the coupled adjoint states equations for tracer concentrations in both the aqueous and NAPL phases. For the sensitivity analysis, we investigate how the tracer concentration in the well changes with perturbations of the saturation within the interrogated zone. Using the calculated sensitivity functions, coupled with the observed tracer breakthrough curve, we develop a nonlinear least-squares inverse method to determine three metrics related to the spatial distribution of DNAPL in the source zone: average DNAPL saturation, total mass of DNAPL and distance of the DNAPL from the test well. These results have utility for local source zone characterization and can provide an initial quantitative understanding of

  13. Use of emulsified vegetable oil to support bioremediation of TCE DNAPL in soil columns

    NASA Astrophysics Data System (ADS)

    Harkness, Mark; Fisher, Angela

    2013-08-01

    The interaction between emulsified vegetable oil (EVO) and trichloroethylene (TCE) dense non-aqueous phase liquid (DNAPL) was observed using two soil columns and subsequent reductive dechlorination of TCE was monitored over a three year period. Dyed TCE DNAPL (~ 75 g) was emplaced in one column (DNAPL column), while the second was DNAPL-free (plume column). EVO was added to both columns and partitioning of the EVO into the TCE DNAPL was measured and quantified. TCE (1.9 mM) was added to the influent of the plume column to simulate conditions down gradient of a DNAPL source area and the columns were operated independently for more than one year, after which they were connected in series. Initially limited dechlorination of TCE to cDCE was observed in the DNAPL column, while the plume column supported complete reductive dechlorination of TCE to ethene. Upon connection and reamendment of the plume column with EVO, near saturation levels of TCE from the effluent of the DNAPL column were rapidly dechlorinated to c-DCE and VC in the plume column; however, this high rate dechlorination produced hydrochloric acid which overwhelmed the buffering capacity of the system and caused the pH to drop below 6.0. Dechlorination efficiency in the columns subsequently deteriorated, as measured by the chloride production and Dehalococcoides counts, but was restored by adding sodium bicarbonate buffer to the influent groundwater. Robust dechlorination was eventually observed in the DNAPL column, such that the TCE DNAPL was largely removed by the end of the study. Partitioning of the EVO into the DNAPL provided significant operational benefits to the remediation system both in terms of electron donor placement and longevity.

  14. Laboratory investigation of flux reduction from dense non-aqueous phase liquid (DNAPL) partial source zone remediation by enhanced dissolution

    NASA Astrophysics Data System (ADS)

    Kaye, Andrew J.; Cho, Jaehyun; Basu, Nandita B.; Chen, Xiaosong; Annable, Michael D.; Jawitz, James W.

    2008-11-01

    This study investigated the benefits of partial removal of dense nonaqueous phase liquid (DNAPL) source zones using enhanced dissolution in eight laboratory scale experiments. The benefits were assessed by characterizing the relationship between reductions in DNAPL mass and the corresponding reduction in contaminant mass flux. Four flushing agents were evaluated in eight controlled laboratory experiments to examine the effects of displacement fluid property contrasts and associated override and underride on contaminant flux reduction ( Rj) vs. mass reduction ( Rm) relationships ( Rj( Rm)): 1) 50% ethanol/50% water (less dense than water), 2) 40% ethyl-lactate/60% water (more dense than water), 3) 18% ethanol/26% ethyl-lactate/56% water (neutrally buoyant), and 4) 2% Tween-80 surfactant (also neutrally buoyant). For each DNAPL architecture evaluated, replicate experiments were conducted where source zone dissolution was conducted with a single flushing event to remove most of the DNAPL from the system, and with multiple shorter-duration floods to determine the path of the Rj( Rm) relationship. All of the single-flushing experiments exhibited similar Rj( Rm) relationships indicating that override and underride effects associated with cosolvents did not significantly affect the remediation performance of the agents. The Rj( Rm) relationship of the multiple injection experiments for the cosolvents with a density contrast with water tended to be less desirable in the sense that there was less Rj for a given Rm. UTCHEM simulations supported the observations from the laboratory experiments and demonstrated the capability of this model to predict Rj( Rm) relationships for non-uniformly distributed NAPL sources.

  15. Characterization of a heterogeneous DNAPL source zone in the Borden aquifer using partitioning and interfacial tracers: residual morphologies and background sorption.

    PubMed

    Hartog, Niels; Cho, Jaehyun; Parker, Beth L; Annable, Michael D

    2010-06-25

    A partitioning interwell tracer test (PITT) was performed in the Borden sand aquifer to characterize an aged heterogeneous DNAPL source zone. This zone evolved during 5 years of natural groundwater flow following the infiltration of 50 L chlorinated solvents DNAPL. To assess the lateral variability of remaining DNAPL mass and morphology, four sweepzones were analyzed. The low saturation residual nature of the source zone required correction of tracer breakthrough data for natural background sorption. Corrected estimates of the DNAPL percentage remaining (total 13.2-16.6%), average saturation (0.05-0.18%) and distribution across the sweepzones were in good agreement with previous findings based on detailed transect monitoring, core analyses and ground-penetrating radar reflection. Using a newly defined metric "average spherical radius equivalent (ASRE)", sweepzone estimates of the average size of DNAPL presence indicated the dominance of single pore DNAPL blobs and suggested the absence of DNAPL pools. Tracer tests indicated that DNAPL presence in the most DNAPL depleted sweepzone was potentially overestimated due to increased sediment sorption by residualized Sudan IV that was added to the DNAPL infiltrate. As hydrophobic compounds are normally present in spent solvent DNAPL, this suggests that additional sorption needs to be considered when using PITTs to characterize aged DNAPL source zones.

  16. Correlation between DNAPL distribution area and dissolved concentration in surfactant enhanced aquifer remediation effluent: a two-dimensional flow cell study

    SciTech Connect

    Wu, Bin; Li, Huiying; Du, Xiaoming; Zhong, Lirong; Yang, Bin; Du, Ping; Gu, Qingbao; Li, Fasheng

    2016-02-01

    During the process of surfactant enhanced aquifer remediation (SEAR), free phase dense non-aqueous phase liquid (DNAPL) may be mobilized and spread. The understanding of the impact of DNAPL spreading on the SEAR remediation is not sufficient with its positive effect infrequently mentioned. To evaluate the correlation between DNAPL spreading and remediation efficiency, a two-dimensional sandbox apparatus was used to simulate the migration and dissolution process of 1,2-DCA (1,2-dichloroethane) DNAPL in SEAR. Distribution area of DNAPL in the sandbox was determined by digital image analysis and correlated with effluent DNAPL concentration. The results showed that the effluent DNAPL concentration has significant positive linear correlation with the DNAPL distribution area, indicating the mobilization of DNAPL could improve remediation efficiency by enlarging total NAPL-water interfacial area for mass transfer. Meanwhile, the vertical migration of 1,2-DCA was limited within the boundary of aquifer in all experiments, implying that by manipulating injection parameters in SEAR, optimal remediation efficiency can be reached while the risk of DNAPL vertical migration is minimized. This study provides a convenient visible and quantitative method for the optimization of parameters for SEAR project, and an approach of rapid predicting the extent of DNAPL contaminant distribution based on the dissolved DNAPL concentration in the extraction well.

  17. DNAPL SITE EVALUATION - Project Summary

    EPA Science Inventory

    Dense nonaqueous-phase liquids (DNAPLs), especially chlorinated solvents, are among the most prevalent subsurface contaminants identified in ground-water supplies and at waste disposal sites. There are several site-characterization issues specific to DNAPL sites including (a) the...

  18. DNAPL SITE EVALUATION - Project Summary

    EPA Science Inventory

    Dense nonaqueous-phase liquids (DNAPLs), especially chlorinated solvents, are among the most prevalent subsurface contaminants identified in ground-water supplies and at waste disposal sites. There are several site-characterization issues specific to DNAPL sites including (a) the...

  19. Evaluating four-dimensional time-lapse electrical resistivity tomography for monitoring DNAPL source zone remediation

    NASA Astrophysics Data System (ADS)

    Power, Christopher; Gerhard, Jason I.; Karaoulis, Marios; Tsourlos, Panagiotis; Giannopoulos, Antonios

    2014-07-01

    Practical, non-invasive tools do not currently exist for mapping the remediation of dense non-aqueous phase liquids (DNAPLs). Electrical resistivity tomography (ERT) exhibits significant potential but has not yet become a practitioner's tool due to challenges in interpreting the survey results at real sites. This study explores the effectiveness of recently developed four-dimensional (4D, i.e., 3D space plus time) time-lapse surface ERT to monitor DNAPL source zone remediation. A laboratory experiment demonstrated the approach for mapping a changing NAPL distribution over time. A recently developed DNAPL-ERT numerical model was then employed to independently simulate the experiment, providing confidence that the DNAPL-ERT model is a reliable tool for simulating real systems. The numerical model was then used to evaluate the potential for this approach at the field scale. Four DNAPL source zones, exhibiting a range of complexity, were initially simulated, followed by modeled time-lapse ERT monitoring of complete DNAPL remediation by enhanced dissolution. 4D ERT inversion provided estimates of the regions of the source zone experiencing mass reduction with time. Results show that 4D time-lapse ERT has significant potential to map both the outline and the center of mass of the evolving treated portion of the source zone to within a few meters in each direction. In addition, the technique can provide a reasonable, albeit conservative, estimate of the DNAPL volume remediated with time: 25% underestimation in the upper 2 m and up to 50% underestimation at late time between 2 and 4 m depth. The technique is less reliable for identifying cleanup of DNAPL stringers outside the main DNAPL body. Overall, this study demonstrates that 4D time-lapse ERT has potential for mapping where and how quickly DNAPL mass changes in real time during site remediation.

  20. Evaluating four-dimensional time-lapse electrical resistivity tomography for monitoring DNAPL source zone remediation.

    PubMed

    Power, Christopher; Gerhard, Jason I; Karaoulis, Marios; Tsourlos, Panagiotis; Giannopoulos, Antonios

    2014-07-01

    Practical, non-invasive tools do not currently exist for mapping the remediation of dense non-aqueous phase liquids (DNAPLs). Electrical resistivity tomography (ERT) exhibits significant potential but has not yet become a practitioner's tool due to challenges in interpreting the survey results at real sites. This study explores the effectiveness of recently developed four-dimensional (4D, i.e., 3D space plus time) time-lapse surface ERT to monitor DNAPL source zone remediation. A laboratory experiment demonstrated the approach for mapping a changing NAPL distribution over time. A recently developed DNAPL-ERT numerical model was then employed to independently simulate the experiment, providing confidence that the DNAPL-ERT model is a reliable tool for simulating real systems. The numerical model was then used to evaluate the potential for this approach at the field scale. Four DNAPL source zones, exhibiting a range of complexity, were initially simulated, followed by modeled time-lapse ERT monitoring of complete DNAPL remediation by enhanced dissolution. 4D ERT inversion provided estimates of the regions of the source zone experiencing mass reduction with time. Results show that 4D time-lapse ERT has significant potential to map both the outline and the center of mass of the evolving treated portion of the source zone to within a few meters in each direction. In addition, the technique can provide a reasonable, albeit conservative, estimate of the DNAPL volume remediated with time: 25% underestimation in the upper 2m and up to 50% underestimation at late time between 2 and 4m depth. The technique is less reliable for identifying cleanup of DNAPL stringers outside the main DNAPL body. Overall, this study demonstrates that 4D time-lapse ERT has potential for mapping where and how quickly DNAPL mass changes in real time during site remediation. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Characterization of DNAPL Source Zone Architecture and Associated Plume Response in 2-D Aquifer Cell Experiments

    NASA Astrophysics Data System (ADS)

    Granbery, E. K.; Cápiro, N.; Christ, J.; Pennell, K.

    2008-12-01

    A series of two-dimensional (2-D) aquifer cell experiments was conducted to evaluate the effects of DNAPL source zone architecture on down-gradient plume and flux-averaged effluent concentrations. The aquifer cells (1.0 m length x 48 cm height x 1.4 cm internal thickness) were packed with different size fractions of quartz sands and low permeability lens configurations to achieve a range of source zone saturation distributions. A mixed DNAPL, consisting of 1:1 trichloroethene (TCE) and tetrachloroethene (PCE), was released into the source zone region of the aquifer cell at a flow rate of 2.0 ml/min and allowed to redistribute for a period of 48 hours. The DNAPL saturation distribution was quantified using a light transmission system and characterized by the ganglia-to-pool ratio (GTP, 0 to infinity) and ganglia fraction (GF, 0-100%), where saturations less than 0.13 represent discrete ganglia and saturations equal to or greater than 0.13 are considered to represent "pools". Effluent dissolved-phase TCE and PCE concentrations were monitored continuously, while down-gradient plume concentrations were collected periodically from 25 side-port samples. To accelerate mass removal, the aquifer cells were flushed with 1.5 pore volumes of 4% Tween 80, a nonionic, food-grade surfactant that has been shown to facilitate microbial reductive dechlorination. Experimental data are used to evaluate interrelationships between the initial source zone architecture, mass removal, reductions in mass flux, and plume evolution.

  2. Integration of Flux-Based Methods and Triad Principles for DNAPL Site Management, Part II: Review of Flux Measurement Methods

    EPA Science Inventory

    Managing dense nonaqueous phase liquid (DNAPL) contaminated sites continues to be among the most pressing environmental problems currently faced. One approach that has recently been investigated for use in DNAPL site characterization and remediation is mass flux (mass per unit ar...

  3. Integration of Flux-Based Methods and Triad Principles for DNAPL Site Management, Part II: Review of Flux Measurement Methods

    EPA Science Inventory

    Managing dense nonaqueous phase liquid (DNAPL) contaminated sites continues to be among the most pressing environmental problems currently faced. One approach that has recently been investigated for use in DNAPL site characterization and remediation is mass flux (mass per unit ar...

  4. Spatial and temporal dynamics of organohalide-respiring bacteria in a heterogeneous PCE-DNAPL source zone

    NASA Astrophysics Data System (ADS)

    Cápiro, Natalie L.; Löffler, Frank E.; Pennell, Kurt D.

    2015-11-01

    Effective treatment of sites contaminated with dense non-aqueous phase liquids (DNAPLs) requires detailed understanding of the microbial community responses to changes in source zone strength and architecture. Changes in the spatial and temporal distributions of the organohalide-respiring Dehalococcoides mccartyi (Dhc) strains and Geobacter lovleyi strain SZ (GeoSZ) were examined in a heterogeneous tetrachloroethene- (PCE-) DNAPL source zone within a two-dimensional laboratory-scale aquifer flow cell. As part of a combined remedy approach, flushing with 2.3 pore volumes (PVs) of 4% (w/w) solution of the nonionic, biodegradable surfactant Tween® 80 removed 55% of the initial contaminant mass, and resulted in a PCE-DNAPL distribution that contained 51% discrete ganglia and 49% pools (ganglia-to-pool ratio of 1.06). Subsequent bioaugmentation with the PCE-to-ethene-dechlorinating consortium BDI-SZ resulted in cis-1,2-dichloroethene (cis-DCE) formation after 1 PV (ca. 7 days), while vinyl chloride (VC) and ethene were detected 10 PVs after bioaugmentation. Maximum ethene yields (ca. 90 μM) within DNAPL pool and ganglia regions coincided with the detection of the vcrA reductive dehalogenase (RDase) gene that exceeded the Dhc 16S rRNA genes by 2.0 ± 1.3 and 4.0 ± 1.7 fold in the pool and ganglia regions, respectively. Dhc and GeoSZ cell abundance increased by up to 4 orders-of-magnitude after 28 PVs of steady-state operation, with 1 to 2 orders-of-magnitude increases observed in close proximity to residual PCE-DNAPL. These observations suggest the involvement of these dechlorinators the in observed PCE dissolution enhancements of up to 2.3 and 6.0-fold within pool and ganglia regions, respectively. Analysis of the solid and aqueous samples at the conclusion of the experiment revealed that the highest VC (≥ 155 μM) and ethene (≥ 65 μM) concentrations were measured in zones where Dhc and GeoSZ were predominately attached to the solids. These findings demonstrate

  5. Spatial and temporal dynamics of organohalide-respiring bacteria in a heterogeneous PCE-DNAPL source zone.

    PubMed

    Cápiro, Natalie L; Löffler, Frank E; Pennell, Kurt D

    2015-11-01

    Effective treatment of sites contaminated with dense non-aqueous phase liquids (DNAPLs) requires detailed understanding of the microbial community responses to changes in source zone strength and architecture. Changes in the spatial and temporal distributions of the organohalide-respiring Dehalococcoides mccartyi (Dhc) strains and Geobacter lovleyi strain SZ (GeoSZ) were examined in a heterogeneous tetrachloroethene- (PCE-) DNAPL source zone within a two-dimensional laboratory-scale aquifer flow cell. As part of a combined remedy approach, flushing with 2.3 pore volumes (PVs) of 4% (w/w) solution of the nonionic, biodegradable surfactant Tween® 80 removed 55% of the initial contaminant mass, and resulted in a PCE-DNAPL distribution that contained 51% discrete ganglia and 49% pools (ganglia-to-pool ratio of 1.06). Subsequent bioaugmentation with the PCE-to-ethene-dechlorinating consortium BDI-SZ resulted in cis-1,2-dichloroethene (cis-DCE) formation after 1 PV (ca. 7 days), while vinyl chloride (VC) and ethene were detected 10 PVs after bioaugmentation. Maximum ethene yields (ca. 90 μM) within DNAPL pool and ganglia regions coincided with the detection of the vcrA reductive dehalogenase (RDase) gene that exceeded the Dhc 16S rRNA genes by 2.0±1.3 and 4.0±1.7 fold in the pool and ganglia regions, respectively. Dhc and GeoSZ cell abundance increased by up to 4 orders-of-magnitude after 28 PVs of steady-state operation, with 1 to 2 orders-of-magnitude increases observed in close proximity to residual PCE-DNAPL. These observations suggest the involvement of these dechlorinators the in observed PCE dissolution enhancements of up to 2.3 and 6.0-fold within pool and ganglia regions, respectively. Analysis of the solid and aqueous samples at the conclusion of the experiment revealed that the highest VC (≥155 μM) and ethene (≥65 μM) concentrations were measured in zones where Dhc and GeoSZ were predominately attached to the solids. These findings demonstrate

  6. COMPATIBILITY OF BENTONITE AND DNAPLS

    EPA Science Inventory

    The compatibility of dense non-aqueous phase liquids (DNAPLs), trichloroethylene (TCE), methylene chloride (MC), and creosote with commercially available sodium bentonite pellets was evaluated using stainless steel, double-ring, falling-head permeameters. The Hydraulic conductiv...

  7. COMPATIBILITY OF BENTONITE AND DNAPLS

    EPA Science Inventory

    The compatibility of dense non-aqueous phase liquids (DNAPLs), trichloroethylene (TCE), methylene chloride (MC), and creosote with commercially available sodium bentonite pellets was evaluated using stainless steel, double-ring, falling-head permeameters. The Hydraulic conductiv...

  8. Compatibility of bentonite and DNAPLs

    SciTech Connect

    McCaulou, D.R.; Huling, S.G.

    1999-10-01

    The compatibility of dense nonaqueous phase liquids (DNAPLs), trichloroethylene (TCE), methylene chloride (MC), and creosote with commercially available sodium bentonite pellets was evaluated using stainless steel, double ring, falling head permeameters. The hydraulic conductivity (K) of the bentonite clay was measured under three experimental conditions: (1) water soluble constituents of the DNAPLs were used to hydrate and permeate the bentonite; (2) bentonite pellets were submersed in DNAPL prior to hydration and permeation with water; and (3) DNAPLs were pooled on water-hydrated bentonite. Further, the effect of hydraulic head on water-hydrated bentonite permeated with TCE and the effects of TCE exposure time to mixtures of bentonite grout and sand were measured.

  9. DNAPL Extraction/Oleofilter Test Report

    SciTech Connect

    White, R.M.; Hazel, C.

    1997-11-03

    A short term, low flow DNAPL extraction test was performed from May 29 - 30, 1997, to gather additional information about the possibility of using monitoring well MSB-3D to recover source contamination from the M-Area Aquifer. Although no visible, free phase material was recovered, the groundwater did contain perchloroethylene (PCE) at and above aqueous solubility. Improvements in the pumping configuration were identified for future trials. Prior to final treatment in the M1 air stripper, the groundwater was passed through an Oleofiltration system to evaluate its capability as a treatment technology. The Oleofilter uses a combination of conventional gravity assisted separation with coalescing plates and a final polishing filter using proprietary coated granules to remove hydrocarbons. Although free phase DNAPL was not processed through the Oleofilter, the groundwater containing high levels of dissolved PCE was treated efficiently. Initially the Oleofilter removed 99 percent of the PCE. As the test progressed, this removal rate decreased to 83 percent as the granules became loaded with PCE. Longer term testing, perhaps with periodic backflushing, is required to determine the effective granule capacity.

  10. Forehead Mass Removal by Endoscopic Approach.

    PubMed

    Jung, Soyeon; Jung, Sung Won; Koh, Sung Hoon; Lim, Hyoseob

    2016-03-01

    Patients with forehead mass have a cosmetic problem because the forehead is an important first impression. Conventional skin approach results in visible scar even though surgeons designed the incision along the relaxed skin tension line1. Since Onishi introduced the technique for endoscopic approach in 1995, endoscopic surgery has become rapidly popular in the field of plastic surgery. Endoscopic approach to the forehead mass by small incision on the scalp behind hair line is big advantageous for leaving less ugly scar on the forehead. All procedures need to be identified under the endoscopic visualization. When it was completed, the mass was pulled out. The authors also used the osteotome or rasp when it was the osteoma. The forehead and scalp were applied compressive dressing to prevent hematoma and swelling for 2 days. The cosmesis was excellent because they have no visible scar on the forehead. Endoscopic approaching technique is getting popular and commonly used during the cosmetic surgery because it has many advantages. This method also, however, has difficulties to remove large-sized mass and to perform caudal dissection, and for increased operative times. Furthermore, there are complication of incomplete removal, hematoma, and swelling. The proper candidate is the patient with smooth forehead, with a mobile and soft mass, with a propensity for keloid formation, or hypertrophic scarring. Endoscopic technique is not only advantageous but also disadvantageous. That is why surgeon's selection is more important.

  11. IMPACTS OF DNAPL SOURCE TREATMENT: OVERVIEW OF GWERD RESEARCH

    EPA Science Inventory

    The Ground Water and Ecosystems Restoration Division (GWERD) is conducting research to evaluate the benefits derived from aggressive DNAPL source treatment. It is assumed that contaminant mass flux from the source zone can be used to estimate the performance of applied remedial ...

  12. Solubilization of DNAPLs by mixed surfactant: reduction in partitioning losses of nonionic surfactant.

    PubMed

    Zhao, Baowei; Zhu, Lizhong; Yang, Kun

    2006-02-01

    Efforts to remediate the dense nonaqueous phase liquids (DNAPLs) by mobilizing them face with risks of driving the contaminants deeper into aquifer zones. This spurs research for modifying the approach for in situ remediation. In this paper, a novel solubilization of DNAPLs by mixed nonionic and anionic surfactant, Triton X-100 (TX100) and sodium dodecylbenzene sulfonate (SDBS), was presented and compared with those by single ones. Given 1:40 phase ratio of DNAPL:water (v/v) and the total surfactant concentration from 0.2 to 10gl(-1), mixed TX100-SDBS at the total mass ratios of 3:1, 1:1 and 1:3 exhibited significant solubilization for the DNAPLs, trichloroethene (TCE), chlorobenzene (CB) and 1,2-dichlorobenzene (1,2-DCB). The solubilization extent by mixed TX100-SDBS was much larger than by single TX100 and even larger than by single SDBS at the ratios of 1:1 and 1:3, respectively. TX100 partitioning into the organic phase dictated the solubilization extent. The TX100 losses into TCE, CB and 1,2-DCB phases were more than 99%, 97% and 97% when single TX100 was used. With SDBS alone, no SDBS partitioned into DNAPLs was observed and in mixed systems, SDBS decreased greatly the partition loss of TX100 into DNAPLs. The extent of TX100 partition decreased with increasing the amount of SDBS. The mechanism for reduction of TX100 partition was discussed. TX100 and SDBS formed mixed micelles in the solution phase. The inability of SDBS to partition into DNAPLs and the mutual affinity of SDBS and TX100 in the mixed micelle controlled the partitioning of TX100 into DNAPL phase. The work presented here demonstrates that mixed nonionic-anionic surfactants would be preferred over single surfactants for solubilization remediation of DNAPLs, which could avoid risks of driving the contaminants deeper into aquifers and decrease the surfactant loss and remediation cost.

  13. Optimal search strategy for the definition of a DNAPL source

    NASA Astrophysics Data System (ADS)

    Dokou, Zoi; Pinder, George F.

    2009-10-01

    SummaryContamination created by dense non-aqueous phase liquids (DNAPLs) is a serious threat to the quality of the groundwater supply; thus, delineating and removing the DNAPL source is an essential step in a successful remediation strategy. The goal of this work is to create an optimal search strategy that identifies a DNAPL source using the least number of water quality samples. The search strategy includes a Monte Carlo stochastic groundwater flow and transport model, a predetermined set of potential source locations and a Kalman filter that updates the simulated contaminant concentration field using contaminant concentration data. The updated plume is compared to the concentration fields that emanate from each individual potential source using a technique rooted in fuzzy set theory. The comparison provides weights that reflect the degree of truth regarding the location of the source at the selected potential source locations. The steps described above are repeated until the weights stabilize and the optimal source location is determined. This paper presents the various mathematical tools employed in the search algorithm and their modifications for incorporation into the proposed methodology. The algorithm's effectiveness in identifying a DNAPL source is shown using a synthetic example.

  14. Self potential observations during DNAPL dissolution

    NASA Astrophysics Data System (ADS)

    Ntarlagiannis, D.; Slater, L.; Kulessa, B.; Russell, C.; Kalin, R.; Ferguson, A.; Graber, J.

    2006-05-01

    Dense non aqueous phase liquids (DNAPLs) are a major environmental problem and are considered to be long term heavy contaminant sources in the subsurface. Accurate monitoring of DNAPL breakdown is required to monitor remediation efforts. We aim to evaluate the efficiency of geophysical methods to monitor DNAPL remediation. Toward this goal we performed self potential (SP) measurements on laboratory columns packed with DNAPL contaminated sand undergoing (a) biodegradation, and (b) abiotic DNAPL dissolution. Geochemical monitoring showed higher concentration of dissolved DNAPL byproducts in the abiotic columns; the use of HgCl2 as a biocide probably increased the rates of DNAPL dissolution in the abiotic columns. The concentration of DNAPL byproducts is significantly lower in the biotic columns due to microbial activity since DNAPL degrading bacteria within the column consume the breakdown products. SP responses are significantly higher (~ 90 mV) in the abiotic columns; in the microbial active columns SP values remain steady with a value ~ 10 mV. High SP signals (up to 110 mV) are associated with DNAPL byproduct concentration gradients within the abiotic columns and exhibit a temporal behavior that mimics total organic carbon concentrations. Although microbial activity in organic rich contaminated areas has been associated with strong negative SP anomalies our results show that positive SP anomalies can also be generated in contaminated areas in the absence of any microbial activity. We discuss a possible SP source mechanism and the implications in geophysical monitoring of DNAPL remedial processes.

  15. Reductive dechlorination of trichloroethene DNAPL source zones: source zone architecture versus electron donor availability

    NASA Astrophysics Data System (ADS)

    Krol, M.; Kokkinaki, A.; Sleep, B.

    2014-12-01

    The persistence of dense-non-aqueous-phase liquids (DNAPLs) in the subsurface has led practitioners and regulatory agencies to turn towards low-maintenance, low-cost remediation methods. Biological degradation has been suggested as a possible solution, based on the well-proven ability of certain microbial species to break down dissolved chlorinated ethenes under favorable conditions. However, the biodegradation of pure phase chlorinated ethenes is subject to additional constraints: the continuous release of electron acceptor at a rate governed by mass transfer kinetics, and the temporal and spatial heterogeneity of DNAPL source zones which leads to spatially and temporally variable availability of the reactants for reductive dechlorination. In this work, we investigate the relationship between various DNAPL source zone characteristics and reaction kinetics using COMPSIM, a multiphase groundwater model that considers non-equilibrium mass transfer and Monod-type kinetics for reductive dechlorination. Numerical simulations are performed for simple, homogeneous trichloroethene DNAPL source zones to demonstrate the effect of single source zone characteristics, as well as for larger, more realistic heterogeneous source zones. It is shown that source zone size, and mass transfer kinetics may have a decisive effect on the predicted bio-enhancement. Finally, we evaluate the performance of DNAPL bioremediation for realistic, thermodynamically constrained, concentrations of electron donor. Our results indicate that the latter may be the most important limitation for the success of DNAPL bioremediation, leading to reduced bio-enhancement and, in many cases, comparable performance with water flooding.

  16. Influence of hydraulic property correlation on predicted dense nonaqueous phase liquid source zone architecture, mass recovery and contaminant flux

    NASA Astrophysics Data System (ADS)

    Lemke, Lawrence D.; Abriola, Linda M.; Lang, John R.

    2004-12-01

    Organic liquid saturation distributions resulting from a simulated tetrachloroethene (PCE) spill were generated with alternative models of spatially varying aquifer properties for a statistically homogeneous, nonuniform sand aquifer. The distributions were analyzed to quantify DNAPL source zone characteristics and then incorporated as initial conditions for simulated PCE recovery using surfactant-enhanced aquifer remediation (SEAR). The predicted evolution of the spatial distribution of DNAPL saturations or source zone "architectures" and associated remediation efficiencies are strongly influenced by the spatial correlation of aquifer parameters and multiphase flow constitutive relationships. Model predictions suggest that removal of 60 to 99% of entrapped PCE can reduce dissolved contaminant concentration and mass flux under natural gradient conditions by approximately two orders of magnitude. Aqueous phase contaminant flux, however, does not vary consistently as a function of the percentage of DNAPL removed, and notable differences in flux evolution were observed for models incorporating correlated versus uncorrelated capillary entry pressure and permeability fields. Simulation results demonstrate that the application of alternative models of aquifer parameter spatial variability can influence predicted DNAPL infiltration, entrapment, and recovery, even for relatively homogeneous aquifers of the type investigated here. Results also demonstrate potential benefits, in the form of reduced mass flux, accruing from partial mass removal that may not be readily predicted from analyses relying on simplified conceptual models for DNAPL source zone architecture or aquifer flow fields.

  17. Radio frequency heating for in-situ remediation of DNAPL

    SciTech Connect

    Kasevich, R.S.

    1996-08-01

    In-situ radio frequency (RF) heating technology for treating soils contaminated with dense nonaqueous phase liquids (DNAPLs) is described. RF imparts heat to non-conducting materials through the application of carefully controlled RF transmissions, improving contaminant flow characteristics and facilitating separation and removal from subsurface soils. The paper outlines advantages and limitations of RF remediation, process operations, general technology considerations, low permeability media considerations, commercial availability, and costs. Two case histories of RF remediation are briefly summarized. 13 refs., 10 figs.

  18. DNAPL invasion into a partially saturated dead-end fracture

    SciTech Connect

    gwsu@lbl.gov

    2004-06-17

    The critical height for DNAPL entry into a partially watersaturated, dead-end fracture is derived and compared to laboratoryobservations. Experiments conducted in an analog, parallel-plate fracturedemonstrate that DNAPL accumulates above the water until the height ofthe DNAPL overcomes the sum of the capillary forces at the DNAPL-airinterface and at the DNAPL-water interface. These experiments also showthat DNAPL preferentially enters the water at locations where DNAPL haspreviously entered, and the entry heights for these subsequent entriesare lower than the heights measured for the initial invasion. The wettingcontact angle at the DNAPL-water interface becomes larger at thelocations where the DNAPL has already entered the water because ofresidual DNAPL on the fracture walls, which results in lowering thecritical entry height at those locations. The experiments alsodemonstrate that a DNAPL lens can remain nearly immobile above the waterfor a period of time before eventually redistributing itself and enteringthe water.

  19. Test plan for single well injection/extraction characterization of DNAPL

    SciTech Connect

    Looney, B.B.; Jerome, K.M.; Burdick, S.; Rossabi, J.; Jarosch, T.R.; Eddy-Dilek, C.A.

    1995-12-01

    Soils and groundwater beneath an abandoned Process sewer line in the A/M Area of the Savannah River Site (SRS) contain elevated levels of volatile organic compounds, specifically trichloroethylene (TCE) and tetrachloroethylene (PCE), two common chlorinated solvents. These compounds have low aqueous solubilities, thus when released to the subsurface in sufficient quantity, tend to exist as immiscible fluids or nonaqueous phase liquids (NAPLs). Because chlorinated solvents are also denser than water, they are referred to by the acronym DNAPLS, or dense non aqueous Phase liquids. Technologies targeted at the efficient characterization or removal of DNAPL are not currently proven. For example, most DNAPL studies rely on traditional soil and water sampling and the fortuitous observation of immiscible solvent. Once DNAPL is identified, soil excavation (which is only applicable to small contained spill sites) is the only ``proven`` cleanup method. New cleanup approaches based on enhanced removal by surfactants and/or alcohols have been proposed and tested at the pilot scale. As described below, carefully designed experiments similar to the enhanced removal methods may provide important characterization information on DNAPLs.

  20. Long-term Behavior of DNAPL Residuals

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Illangasekare, T.; Kitanidis, P. K.

    2012-12-01

    Understanding and being able to predict the long-term behavior of DNAPL (i.e., TCE) residuals in the source zone are significant in the evaluation of plume spreading. We apply both theoretical analysis and pore-scale simulations to investigate the mass transfer and the effect of reductive dechlorination, in which the contaminant behaves as electron acceptor. At the upfront of the source zone, where the boundary layer has not fully developed, the mass transfer increases as a power-law function of the Peclet number, and is enhanced by biodegradation. These results are consistent with past findings. Under certain conditions, further downstream inside the source zone, the rate of dissolution is slower due to the diluted mass from upstream. Widely applied first-order biodegradation implicitly assumes that the reaction solely depends on the concentration of the contaminant. However, in the slow dilution region, the limitation of electron donor on biodegradation is not negligible. For the reaction between an electron donor and an electron acceptor with intrinsic second-order kinetics, the late-time bio-reaction demonstrates a first-order decay macroscopically with respect to the mass of electron donor, not with respect to that of the contaminant. The late-time decay rate only depends on the intrinsic rate and the solubility of the contaminant. During the intermediate time, affecting by both the concentrations of electron donor and electron acceptor, the first-order decay is not valid. We show that the electron donor decays as exp(-t^2), instead of exp(-t). Moreover, the intermediate-time decay rate is a function of the spatial distribution of DNAPL residuals and the initial conditions.he relationship of the Sherwood number and Peclet number (Comparison of pore-scale simulations and best-fitting curve) he decay of electron donor as a function of t^2

  1. Steam injection for in-situ remediation of DNAPLs in low permeability media

    SciTech Connect

    Sleep, B.

    1996-08-01

    The potential for remediation of dense, nonaqueous phase liquid (DNAPL) contamination by steam injection is investigated, including the advantages and disadvantages of the technology. The primary advantage is the significant enhancement of removal rates through steam distillation. The disadvantages are related to the lack of field experience with the technology and difficulties related to steam override and channeling in heterogeneous soils. The problems related to steam injection in low permeability fractured clay are examined, and removal times and costs are postulated for a hypothetical DNAPL contamination scenario. It is concluded that steam injection has significant potential for remediation of DNAPL in fractured clay soils, but there is significant uncertainty in predictions of the performance of steam injection in these soils. 13 refs., 4 figs., 1 tab.

  2. Application of 4D resistivity image profiling to detect DNAPLs plume.

    NASA Astrophysics Data System (ADS)

    Liu, H.; Yang, C.; Tsai, Y.

    2008-12-01

    iron nanoparticles with pumps water remediation ways. The survey lines use the same length and the same position of the different time observation. The survey lines monitors the iron nanoparticles and pollution flow direction with remediation effect. By used the iron nanoparticles and pumping water remediation ways, the DNAPL plumes had eminent changed. Iron nanoparticles granule is smaller than the micron iron, Therefore the reaction rate was quite quick at the iron nanoparticles and pumps, but the ferric oxide can cause the electronic resistivity to elevate produces after the response. Pumps water rectifies may remove the ferric oxide to cause the electronic resistivity to reduce. The iron nanoparticles and pollution response is extremely obviously of the Resistivity Image Profile.

  3. Complex Electrical Resistivity for Monitoring DNAPL Contamination

    SciTech Connect

    Stephen R. Brown; David Lesmes; John Fourkas

    2003-09-12

    Nearly all Department of Energy (DOE) facilities have landfills and buried waste areas. Of the various contaminants present at these sites, dense non-aqueous phase liquids (DNAPL) are particularly hard to locate and remove. There is an increasing need for external or non-invasive sensing techniques to locate DNAPLs in the subsurface and to track their spread and monitor their breakdown or removal by natural or engineered means. G. Olhoeft and colleagues have published several reports based on laboratory studies using the complex resistivity method which indicate that organic solvents, notably toluene, PCE, and TCE, residing in clay-bearing soils have distinctive electrical signatures. These results have suggested to many researchers the basis of an ideal new measurement technique for geophysical characterization of DNAPL pollution. Encouraged by these results we proposed to bring the field measurement of complex resistivity as a means of pollution characterization from the conceptual stage to practice. We planned to document the detectability of clay-organic solvent interactions with geophysical measurements in the laboratory, develop further understanding of the underlying physical and chemical mechanisms, and then apply these observations to develop field techniques. As with any new research endeavor we note the extreme importance of trying to reproduce the work of previous researchers to ensure that any effects observed are due to the physical phenomena occurring in the specimen and not due to the particular experimental apparatus or method used. To this end, we independently designed and built a laboratory system, including a sample holder, electrodes, electronics, and data analysis software, for the measurement of the complex electrical resistivity properties of soil contaminated with organic solvents. The capabilities and reliability of this technique were documented. Using various standards we performed measurement accuracy, repeatability, and noise immunity

  4. Surfactant enhanced remediation of an alluvial aquifer contaminated with DNAPL

    SciTech Connect

    Londergan, J.T.; Meinardus, H.W.; Pope, G.A.; Brown, C.L.

    1997-12-31

    During 1996, a successful demonstration of surfactant-enhanced-aquifer-remediation (SEAR) and the use of partitioning interwell tracer tests (PITTs) was conducted beneath the former waste disposal trenches at Operable Unit 2 at Hill AFB, Utah. The trenches had received large volumes of chlorinated solvents from degreasing operations. The solvents drained downward, pooling in an alluvial sand aquifer confined in a buried paleochannel eroded into thick clay deposits. The hydraulic conductivity of the alluvium is in the range of 10{sup -3} to 10{sup -2} cm/sec. The well array installed for the demonstration consisted of a line of three injection wells, a line of three extraction wells, a central observation well, and a single hydraulic control well. The distance between injectors and extractors was 20 feet; the distance between individual injectors and extractors in line was 10 feet. The water table was 25 feet below ground surface with a saturated zone approximately 19 feet thick. There was a 4 foot thick zone of DNAPL 42-46 feet below ground surface. The injectors and extractors were completed in this DNAPL zone. The demonstration was conducted in two phases. The first of these consisted of an initial partitioning interwell tracer test (PITT) followed by a pilot scale surfactant flood. The PITT indicated that a total of approximately 346 gallons of DNAPL was present in, the demonstration area. The pilot scale surfactant flood demonstrated the efficacy of the surfactant, showed there was no degradation of hydraulic conductivity due to the introduction of a surfactant solution, and demonstrated that the effluent could be efficiently treated by the on-site steam stripper. Approximately 185 gallons of DNAPL were removed from the aquifer by the pilot scale surfactant flood. The second phase consisted of a pre-flood PITT, a line drive surfactant flood, and a post-flood PITT.

  5. Transport, Targeting, and Applications of Metallic Functional Nanoparticles for Degradation of DNAPL Chlorinated Organic solvents

    SciTech Connect

    Lowry, Gregory; Majetich, Sara; Matyjaszewski, Krzysztof; Sholl, David; Tilton, Robert

    2004-06-15

    This project addresses the need for methods to remove or degrade subsurface contaminants that are present as dense non-aqueous phase liquids (DNAPLs), and act as long-term sources of groundwater contamination. The goal is to build on a particle-based approach to subsurface contaminant remediation that is based partly on the recent success in using nanoparticle iron to degrade chlorinated compounds dissolved in groundwater, and knowledge of how colloids migrate in porous media. The objective is to engineer reactive nanoparticles that can decompose and potentially isolate DNAPL pollutants in the subsurface.

  6. Visualization Methods to Quantify DNAPL Dynamics in Chemical Remediation

    NASA Astrophysics Data System (ADS)

    Wang, H.; Chen, X.; Jawitz, J. W.

    2006-12-01

    A novel multiple-wavelength visualization method is under development for quantifying multiphase fluid dynamics in porous media. This technique is applied here for in situ characterization of laboratory-scale DNAPL chemical remediation, including co-solvent flushing and surfactant flushing. Development of this method is motivated by the limitations of current quantitative imaging methods. In the method both light adsorption (Beer's Law) and interfacial diffraction (Fresnel's Law) are considered. Furthermore, the use of multiple wavelengths introduces the ability to eliminate the interface structure effect. By using images taken at two wavelengths using band-pass filters, the heterogeneous DNAPL saturation distribution in a two- dimensional laboratory chamber can be quantified at any time during chemical remediation. Previously published DNAPL visualization techniques have been shown to be some accurate for post-spill conditions, but are ineffective once significant dissolution has occurred. The method introduced here is shown to achieve mass balances of 90% and greater even during chemical remediation. Furthermore, the heterogeneous saturation distribution in the chamber (i.e. Eulerian description) and the distribution over stream tubes (i.e. Lagrangian description) are quantified using the new method and shown to be superior to those obtained using the binary imaging technique.

  7. ENHANCED MOBILITY OF DENSE NONAQUEOUS-PHASE LIQUIDS (DNAPLs) USING DISSOLVED HUMIC ACIDS

    SciTech Connect

    EDWIN S. OLSON; JOHN R. GALLAGHER; MARC D. KURZ

    1998-10-01

    The specific objectives of this subtask are as follows: � Evaluate the suitability of using humic acids to enhance the solubility and mobility of DNAPL contaminants sorbed to soils. � Evaluate the toxicity and bioavailablity of the DNAPLs to biodegrading microorganisms. To meet the first objective, the Energy & Environmental Research Center (EERC) evaluated a set of humic acids (two) with different chemical compositions and polarities for the following: � Ability of the humates to mobilize/solubilize selected (three) DNAPLs � Mobilization/solubilization in batch soil�water experiments (one soil) � Removal rate via biotreatment with a well-established active microbial culture. The second objective was met by evaluating the inhibiting effects of a leonardite-derived humic acid on active microbial populations.

  8. SYNTHESIS REPORT ON FIVE DENSE, NONAQUEOUS-PHASE LIQUID (DNAPL) REMEDIATION PROJECTS

    EPA Science Inventory

    Dense non-aqueous phase liquid (DNAPL) poses a difficult problem for subsurface remediation because it serves as a continuing source to dissolved phase ground water contamination and is difficult to remove from interstitial pore space or bedrock fractures in the subsurface. Numer...

  9. SYNTHESIS REPORT ON FIVE DENSE, NONAQUEOUS-PHASE LIQUID (DNAPL) REMEDIATION PROJECTS

    EPA Science Inventory

    Dense non-aqueous phase liquid (DNAPL) poses a difficult problem for subsurface remediation because it serves as a continuing source to dissolved phase ground water contamination and is difficult to remove from interstitial pore space or bedrock fractures in the subsurface. Numer...

  10. Field-scale prediction of enhanced DNAPL dissolution based on partitioning tracers.

    PubMed

    Wang, Fang; Annable, Michael D; Jawitz, James W

    2013-09-01

    The equilibrium streamtube model (EST) has demonstrated the ability to accurately predict dense nonaqueous phase liquid (DNAPL) dissolution in laboratory experiments and numerical simulations. Here the model is applied to predict DNAPL dissolution at a tetrachloroethylene (PCE)-contaminated dry cleaner site, located in Jacksonville, Florida. The EST model is an analytical solution with field-measurable input parameters. Measured data from a field-scale partitioning tracer test were used to parameterize the EST model and the predicted PCE dissolution was compared to measured data from an in-situ ethanol flood. In addition, a simulated partitioning tracer test from a calibrated, three-dimensional, spatially explicit multiphase flow model (UTCHEM) was also used to parameterize the EST analytical solution. The EST ethanol prediction based on both the field partitioning tracer test and the simulation closely matched the total recovery well field ethanol data with Nash-Sutcliffe efficiency E=0.96 and 0.90, respectively. The EST PCE predictions showed a peak shift to earlier arrival times for models based on either field-measured or simulated partitioning tracer tests, resulting in poorer matches to the field PCE data in both cases. The peak shifts were concluded to be caused by well screen interval differences between the field tracer test and ethanol flood. Both the EST model and UTCHEM were also used to predict PCE aqueous dissolution under natural gradient conditions, which has a much less complex flow pattern than the forced-gradient double five spot used for the ethanol flood. The natural gradient EST predictions based on parameters determined from tracer tests conducted with a complex flow pattern underestimated the UTCHEM-simulated natural gradient total mass removal by 12% after 170 pore volumes of water flushing indicating that some mass was not detected by the tracers likely due to stagnation zones in the flow field. These findings highlight the important

  11. Test plan for Geo-Cleanse{reg_sign} demonstration (in situ destruction of dense non-aqueous phase liquid (DNAPL))

    SciTech Connect

    Jerome, K.M.; Looney, B.B.; Accorsi, F.; Dingens, M.; Wilson, J.T.

    1996-09-01

    Soils and groundwater beneath an abandoned process sewer line in the A/M Area of the Savannah River Site (SRS) contain elevated levels of volatile organic compounds, specifically trichloroethylene (TCE) and tetrachloroethylene (PCE), two common chlorinated solvents. These compounds have low aqueous solubilities, thus when released to the subsurface in sufficient quantity, tend to exist as immiscible fluids or nonaqueous phase liquids (NAPLs). Because chlorinated solvents are also denser than water, they are referred to by the acronym DNAPLs, or dense non-aqueous phase liquids. Technologies targeted at the efficient characterization or removal of DNAPL are not currently proven. For example, most DNAPL studies rely on traditional soil and water sampling and the fortuitous observation of immiscible solvent. Once DNAPL is identified, soil excavation (which is only applicable to small contained spill sites) is the only proven cleanup method. New cleanup approaches based on destruction of DNAPL either in situ or ex situ have been proposed and tested at the pilot scale. The proposed demonstration, as described in this report will evaluate the applicability to DNAPL plumes of a technology proven for in situ destruction of light non-aqueous phase liquids (LNAPLs) such as oils.

  12. RELATIONSHIP BETWEEN MASS FLUX REDUCTION AND SOURCE-ZONE MASS REMOVAL: ANALYSIS OF FIELD DATA

    PubMed Central

    DiFilippo, Erica L.

    2010-01-01

    The magnitude of contaminant mass flux reduction associated with a specific amount of contaminant mass removed is a key consideration for evaluating the effectiveness of a source-zone remediation effort. Thus, there is great interest in characterizing, estimating, and predicting relationships between mass flux reduction and mass removal. Published data collected for several field studies were examined to evaluate relationships between mass flux reduction and source-zone mass removal. The studies analyzed herein represent a variety of source-zone architectures, immiscible-liquid compositions, and implemented remediation technologies. There are two general approaches to characterizing the mass-flux-reduction/mass-removal relationship, end-point analysis and time-continuous analysis. End-point analysis, based on comparing masses and mass fluxes measured before and after a source-zone remediation effort, was conducted for 21 remediation projects. Mass removals were greater than 60% for all but three of the studies. Mass flux reductions ranging from slightly less than to slightly greater than one-to-one were observed for the majority of the sites. However, these single-snapshot characterizations are limited in that the antecedent behavior is indeterminate. Time-continuous analysis, based on continuous monitoring of mass removal and mass flux, was performed for two sites, both for which data were obtained under water-flushing conditions. The reductions in mass flux were significantly different for the two sites (90% vs. ~8%) for similar mass removals (~40%). These results illustrate the dependence of the mass-flux-reduction/mass-removal relationship on source-zone architecture and associated mass-transfer processes. Minimal mass flux reduction was observed for a system wherein mass removal was relatively efficient (ideal mass transfer and displacement). Conversely, a significant degree of mass flux reduction was observed for a site wherein mass removal was inefficient

  13. Safe and cost-effective laparoscopic removal of adnexal masses.

    PubMed

    Quinlan, D J; Townsend, D E; Johnson, G H

    1997-02-01

    To evaluate laparoscopic removal of adnexal masses using a plastic bag to avoid peritoneal spillage. An observational study. A university-affiliated private hospital. Thirty-one women (mean age 48.7 yrs) with adnexal masses. Laparoscopic removal of adnexal masses ranging from 3 to 12 cm (18 complex, 5 septated cystic masses, 8 persistent simple cysts). The masses were placed in plastic sandwich bag and removed through the umbilical incision. Hospital costs, length of stay and operating times were compared with those of 24 patients undergoing the removal of similar masses by laparotomy. Three masses were functional cysts, 4 were tubal cysts, 4 were endometriomas, and 20 were benign ovarian neoplasms. There were no malignancies. Peritoneal spillage occurred during one ovarian cystectomy. The only complication was bleeding from the cannula site. Comparing laparoscopy and laparotomy, average operating time was 73.45 minutes (range 34-148 min) and 81 minutes, average length of hospital stay was 17.4 hours (range 6-73 hrs) and 2.92 days, and average hospital cost was $2401 and $3539, respectively. Laparoscopic access provides a cost-effective method of removing adnexal masses with a very small risk of peritoneal spillage. When managed in this manner, rather than laparotomy, the cost reduction was significant.

  14. Processes affecting soil and groundwater contamination by DNAPL in low-permeability media

    SciTech Connect

    McWhorter, D.B.

    1996-08-01

    This paper is one of a set of focus papers intended to document the current knowledge relevant to the contamination and remediation of soils and ground water by dense, nonaqueous phase liquids (DNAPL). The emphasis is on low permeability media such as fractured clay and till and unconsolidated, stratified formations. Basic concepts pertaining to immiscible-fluid mixtures are described and used to discuss such aspects as DNAPL transport, dissolved-phase transport, and equilibrium mass distributions. Several implications for remediation are presented. 27 refs., 8 figs., 4 tabs.

  15. Time-Dependent Interfacial Properties and DNAPL Mobility

    SciTech Connect

    Tuck, D.M.

    1999-03-10

    Interfacial properties play a major role in governing where and how dense nonaqueous phase liquids (DNAPLs) move in the subsurface. Interfacial tension and contact angle measurements were obtained for a simple, single component DNAPL (tetrachloroethene, PCE), complex laboratory DNAPLs (PCE plus Sudan IV dye), and a field DNAPL from the Savannah River Site (SRS) M-Area DNAPL (PCE, trichloroethene [TCE], and maching oils). Interfacial properties for complex DNAPLs were time-dependent, a phenomenon not observed for PCE alone. Drainage capillary pressure-saturation curves are strongly influenced by interfacial properties. Therefore time-dependence will alter the nature of DNAPL migration and penetration. Results indicate that the time-dependence of PCE with relatively high Sudan IV dye concentrations is comparable to that of the field DNAPL. Previous DNAPL mobility experiments in which the DNAPL was dyed should be reviewed to determine whether time-dependent properties influenced the resutls. Dyes appear to make DNAPL more complex, and therefore a more realistic analog for field DNAPLs than single component DNAPLs.

  16. Site Characterization Technologies for DNAPL Investigations

    EPA Pesticide Factsheets

    This document is intended to help managers at sites with potential or confirmed DNAPL contamination identify suitable characterization technologies, screen the technologies for potential application, learn about applications at similar sites, and...

  17. Does increasing the temperature induce DNAPL migration?

    EPA Science Inventory

    Tetrachloroethylene, trichloroethylene, and chlorobenzene have been identified as contaminants in groundwater and are sometimes called Dense Non-Aqueous Phase Liquids (DNAPL). Thermal methods for remediation of contaminated soils and groundwater rely on raising the temperature o...

  18. DNAPL Remediation: Selected Projects Approaching Regulatory Closure

    EPA Pesticide Factsheets

    This paper is a status update on the use of DNAPL source reduction remedial technologies, and provides information about recent projects where regulatory closure has been reached or projects are approaching regulatory closure, following source reduction.

  19. FIELD ASSESSMENT OF MULTIPLE DNAPL REMEDIATION TECHNIQUES

    EPA Science Inventory

    Five DNAPL remediation technologies were evaluated in constructed test cells at the Dover National Test Site, Dover AFB, Delaware. The technologies were cosolvent solubilization, cosolvent mobilization, surfactant solubilization, complex sugar flushing and air sparging/soil vapor...

  20. Does increasing the temperature induce DNAPL migration?

    EPA Science Inventory

    Tetrachloroethylene, trichloroethylene, and chlorobenzene have been identified as contaminants in groundwater and are sometimes called Dense Non-Aqueous Phase Liquids (DNAPL). Thermal methods for remediation of contaminated soils and groundwater rely on raising the temperature o...

  1. High-resolution experiments on chemical oxidation of DNAPL in variable-aperture fractures

    NASA Astrophysics Data System (ADS)

    Arshadi, Masoud; Rajaram, Harihar; Detwiler, Russell L.; Jones, Trevor

    2015-04-01

    Chemical oxidation of dense nonaqueous-phase liquids (DNAPLs) by permanganate has emerged as an effective remediation strategy in fractured rock. We present high-resolution experimental investigations in transparent analog variable-aperture fractures to improve understanding of chemical oxidation of residual entrapped trichloroethylene (TCE) in fractures. Four experiments were performed with different permanganate concentrations, flow rates, and initial TCE phase geometry. The initial aperture field and evolving entrapped-phase geometry were quantified for each experiment. The integrated mass transfer rate from the TCE phase for all experiments exhibited three time regimes: an early-time regime with slower mass transfer rates limited by low specific interfacial area; an intermediate-time regime with higher mass transfer rates resulting from breakup of large TCE blobs, which greatly increases specific interfacial area; and a late-time regime with low mass transfer rates due to the deposition of MnO2 precipitates. In two experiments, mass balance analyses suggested that TCE mass removal rates exceeded the maximum upper bound mass removal rates derived by assuming that oxidation and dissolution are the only mechanisms for TCE mass removal. We propose incomplete oxidation by permanganate and TCE solubility enhancement by intermediate reaction products as potential mechanisms to explain this behavior. We also speculate that some intermediate reaction products with surfactant-like properties may play a role in lowering the TCE-water interfacial tension, thus causing breakup of large TCE blobs. Our quantitative experimental measurements will be useful in the context of developing accurate computational models for chemical oxidation of TCE in fractures.

  2. Relative contribution of DNAPL dissolution and matrix diffusion to the long-term persistence of chlorinated solvent source zones

    NASA Astrophysics Data System (ADS)

    Seyedabbasi, Mir Ahmad; Newell, Charles J.; Adamson, David T.; Sale, Thomas C.

    2012-06-01

    The relative contribution of dense non-aqueous phase liquid (DNAPL) dissolution versus matrix diffusion processes to the longevity of chlorinated source zones was investigated. Matrix diffusion is being increasingly recognized as an important non-DNAPL component of source behavior over time, and understanding the persistence of contaminants that have diffused into lower permeability units can impact remedial decision-making. In this study, a hypothetical DNAPL source zone architecture consisting of several different sized pools and fingers originally developed by Anderson et al. (1992) was adapted to include defined low permeability layers. A coupled dissolution-diffusion model was developed to allow diffusion into these layers while in contact with DNAPL, followed by diffusion out of these same layers after complete DNAPL dissolution. This exercise was performed for releases of equivalent masses (675 kg) of three different compounds, including chlorinated solvents with solubilities ranging from low (tetrachloroethene (PCE)), moderate (trichloroethene (TCE)) to high (dichloromethane (DCM)). The results of this simple modeling exercise demonstrate that matrix diffusion can be a critical component of source zone longevity and may represent a longer-term contributor to source longevity (i.e., longer time maintaining concentrations above MCLs) than DNAPL dissolution alone at many sites. For the hypothetical TCE release, the simulation indicated that dissolution of DNAPL would take approximately 38 years, while the back diffusion from low permeability zones could maintain the source for an additional 83 years. This effect was even more dramatic for the higher solubility DCM (97% of longevity due to matrix diffusion), while the lower solubility PCE showed a more equal contribution from DNAPL dissolution vs. matrix diffusion. Several methods were used to describe the resulting source attenuation curves, including a first-order decay model which showed that half-life of

  3. Numerical simulation of in-situ DNAPL remediation by alcohol flooding

    SciTech Connect

    Falta, R.W.; Brame, S.E.

    1995-03-01

    The removal of residual saturations of dense non-aqueous phase liquids (DNAPLs) from below the water table using alcohol solutions is under investigation as a potential remediation tool. Alcohol flooding reduces the interfacial tension (IFT) an density difference between the aqueous and DNAPL phases, and increases the chemical solubility in the aqueous phase. Depending on the partitioning behavior of the alcohol/chemical system, DNAPL can be removed by either mobilization as a separate phase or through enhanced dissolution. A new three dimensional multiphase numerical simulator has been developed for modeling this process. The code is based on the general TOUGH2 Integral Finite Difference formulation for multiphase transport with modifications to account for the complex behavior of an alcohol/water/DNAPL system. The alcohol flood code uses a special equation of state module for computing phase compositions, IFT, saturations, densities, viscosities, relative permeabilities, and capillary pressures during each time step. This equation of state is based on a numerical interpolation of experimentally determined ternary phase data. The code was designed so that it can readily be applied to other three-component, two-phase problems such as surfactant and solvent floods given appropriate ternary data. Comparisons of simulation results with column experiments performed at Clemson University were used to validate the simulator.

  4. Long-term ground penetrating radar monitoring of a small volume DNAPL release in a natural groundwater flow field.

    PubMed

    Hwang, Yong Keun; Endres, Anthony L; Piggott, Scott D; Parker, Beth L

    2008-04-04

    An earlier field experiment at Canadian Forces Base Borden by Brewster and Annan [Geophysics 59 (1994) 1211] clearly demonstrated the capability of ground penetrating radar (GPR) reflection profiling to detect and monitor the formation of DNAPL layers in the subsurface. Their experiment involved a large volume release (770 L) of tetrachloroethylene into a portion of the sand aquifer that was hydraulically isolated from groundwater flow by sheet pile walls. In this study, we evaluated the ability of GPR profiling to detect and monitor much smaller volume releases (50 L). No subsurface confining structure was used in this experiment; hence, the DNAPL impacted zone was subjected to the natural groundwater flow regime. This condition allowed us to geophysically monitor the DNAPL mass loss over a 66 month period. Reflectivity variations on the GPR profiles were used to infer the presence and evolution of the solvent layers. GPR imaging found significant reflectivity increases due to solvent layer formation during the two week period immediately after the release. These results demonstrated the capacity of GPR profiling for the detection and monitoring of lesser volume DNAPL releases that are more representative of small-scale industrial spills. The GPR imaged solvent layers subsequently reduced in both areal extent and reflectivity after 29 months and almost completely disappeared by the end of the 66 month monitoring period. Total DNAPL mass estimates based on GPR profiling data indicated that the solvent mass was reduced to 34%-36% of its maximum value after 29 months; only 4%-9% of the solvent mass remained in the study area after 66 months. These results are consistent with independent hydrogeological estimates of remaining DNAPL mass based on the downgradient monitoring of the dissolved solvent phase. Hence, we have concluded that the long-term GPR reflectivity changes of the DNAPL layers are likely the result from the dissolution of chlorinated solvents residing

  5. Modeling Bioenhanced DNAPL Dissolution in 1-D and 2-D Flow systems

    NASA Astrophysics Data System (ADS)

    Wesseldyke, E. S.; Becker, J. G.; Seagren, E. A.; Mayer, A. S.

    2011-12-01

    Chlorinated ethenes, such as tetrachloroethene (PCE), released into the environment can form dense non-aqueous phase liquids (DNAPLs), which can act as persistent sources of contamination to groundwater. Due to their low aqueous solubility, these DNAPL contaminant sources can persist for up to hundreds of years under natural conditions. Several methods have been investigated to enhance the rate of dissolution of DNAPLs, including bioenhanced dissolution, which consists of stimulating the growth of a microbial population that biodegrades the contaminant, thereby reducing its concentration at the DNAPL-water interface, and creating a greater driving force for contaminant dissolution. This phenomenon has been studied at length in batch reactors and column studies. The hypothesis of this research is that, in modeling DNAPL dissolution bioenhancement via dehalorespiration, it is important to include the effects of microbial competition, as well as spatial effects. A two-dimensional coupled flow-transport model was developed using the finite-volume method (FVM), which includes a DNAPL pool source, and the effects of multiple microbial species. The model has been confirmed to maintain mass balance and has been validated by comparison to an analytical solution for pool dissolution. The model will be used to simulate a pseudo one-dimensional system and a two-dimensional system under multiple microbial competition scenarios and varying hydrodynamic conditions. The results of these simulations will be compared to determine differences in estimations of dissolution bioenhancement, and analyzed for spatial effects that are captured by a two-dimensional model, but not by a pseudo one-dimensional FVM model. Preliminary two-dimensional simulations have shown the effects of large biomass growth near the NAPL source, which could lead to bioclogging and change the flow field. Further simulations are underway and the results will be presented.

  6. In situ remediation of DNAPL compounds in low permeability media fate/transport, in situ control technologies, and risk reduction

    SciTech Connect

    1996-08-01

    In this project, in situ remediation technologies are being tested and evaluated for both source control and mass removal of dense, non-aqueous phase liquid (DNAPL) compounds in low permeability media (LPM). This effort is focused on chlorinated solvents (e.g., trichloroethylene and perchloroethylene) in the vadose and saturated zones of low permeability, massive deposits, and stratified deposits with inter-bedded clay lenses. The project includes technology evaluation and screening analyses and field-scale testing at both clean and contaminated sites in the US and Canada. Throughout this project, activities have been directed at understanding the processes that influence DNPAL compound migration and treatment in LPM and to assessing the operation and performance of the remediation technologies developed and tested. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  7. Task 1.16 - Enhanced Mobility of Dense Nonaqueous-Phase Liquids (DNAPLs) Using Dissolved Humic Acids

    SciTech Connect

    Edwin S. Olson; Marc D. Kurz

    1998-02-01

    Chlorinated solvent contamination is widespread across the U.S. Department of Energy (DOE) complex and other industrial facilities. Because of the physical properties of dense nonaqueous-phase liquids (DNAPLs), current treatment technologies are generally incapable of completely removing contamination from the source area. Incomplete removal means that the residual DNAPL WN persist as a long-term source of groundwater contamination. When DNALPs occur in the subsurface, they resist remediation, owing to low water volubility, high viscosity and interracial tension, and microbial recalcitrance. Because of their high density and polarity, they are usually found sorbed to aquifer solids or in pools on impermeable materials. Surfactants have been used with some success to reduce interracial tension between the aqueous and organic phases and improve volubility of DNAPLs. However, surfactants are expensive and toxic and exhibit an oxygen demand. An alternative is the use of dissolved humic acids in improving DNAPL mobilization and solubilization. Humic acids, a natural form of organic carbon, are abundant, inexpensive, and nontoxic; biodegrade slowly (low oxygen demand); and have excellent mobilization properties. The present work is to establish the feasibility of using hurnates for enhancing DNAPL remediation.

  8. Nasal mass removal in the koala (Phascolarctos cinereus).

    PubMed

    Bercier, Marjorie; Wynne, Janna; Klause, Stephen; Stadler, Cynthia K; Gorow, April; Pye, Geoffrey W

    2012-12-01

    Nasal masses in the koala (Phascolarctos cinereus) are not uncommon and can be challenging to diagnose and treat. Differential diagnoses for nasal masses in the koala are cryptococcal granulomas, nasal polyps, nasal adenocarcinoma, and osteochondromatosis. This report describes successful surgical approaches for two adult koalas with nasal masses and includes photodocumentation and description of the anatomy of the koala nasal passages from the postmortem transverse sectioning of a normal koala head. Surgical removal of the nasal masses in these koalas resulted in a rapid resolution of clinical signs.

  9. Electroosmosis remediation of DNAPLS in low permeability soils

    SciTech Connect

    Ho, S V.

    1996-08-01

    Electroosmosis is the movement of water through a soil matrix induced by a direct current (DC) electric field. The technique has been used since the 1930s for dewatering and stabilizing fine-grained soils. More recently, electroosmosis has been considered as an in-situ method for soil remediation in which water is injected into the soil at the anode region to flush the contaminants to the cathode side for further treatment or disposal. The major advantage of electroosmosis is its inherent ability to move water uniformly through clayey, silty soils at 100 to 1000 times faster than attainable by hydraulic means, and with very low energy usage. Drawbacks of electroosmosis as a stand-alone technology include slow speed, reliance on solubilizing the contaminants into the groundwater for removal, potentially an unstable process for long term operation, and necessary additional treatment and disposal of the collected liquid. Possible remediation applications of electroosmosis for DNAPLs would be primarily in the removal of residual DNAPLs in the soil pores by electroosmotic flushing. The future of electroosmosis as a broad remedial method lies in how well it can be coupled with complementary technologies. Examples include combining electroosmosis with vacuum extraction, with surfactant usage to deal with non-aqueous phase liquids (NAPLs) through enhanced solubilization or mobilization, with permeability enhancing methods (hydrofracturing, pneumatic fracturing, etc.) to create recovery zones, and with in-situ degradation zones to eliminate aboveground treatment. 33 refs., 1 fig., 1 tab.

  10. Interpreting DNAPL saturations in a laboratory-scale injection using one- and two-dimensional modeling of GPR Data

    USGS Publications Warehouse

    Johnson, R.H.; Poeter, E.P.

    2005-01-01

    Ground-penetrating radar (GPR) is used to track a dense non-aqueous phase liquid (DNAPL) injection in a laboratory sand tank. Before modeling, the GPR data provide a qualitative image of DNAPL saturation and movement. One-dimensional (1D) GPR modeling provides a quantitative interpretation of DNAPL volume within a given thickness during and after the injection. DNAPL saturation in sublayers of a specified thickness could not be quantified because calibration of the 1D GPR model is nonunique when both permittivity and depth of multiple layers are unknown. One-dimensional GPR modeling of the sand tank indicates geometric interferences in a small portion of the tank. These influences are removed from the interpretation using an alternate matching target. Two-dimensional (2D) GPR modeling provides a qualitative interpretation of the DNAPL distribution through pattern matching and tests for possible 2D influences that are not accounted for in the 1D GPR modeling. Accurate quantitative interpretation of DNAPL volumes using GPR modeling requires (1) identification of a suitable target that produces a strong reflection and is not subject to any geometric interference; (2) knowledge of the exact depth of that target; and (3) use of two-way radar-wave travel times through the medium to the target to determine the permittivity of the intervening material, which eliminates reliance on signal amplitude. With geologic conditions that are suitable for GPR surveys (i.e., shallow depths, low electrical conductivities, and a known reflective target), the procedures in this laboratory study can be adapted to a field site to delineate shallow DNAPL source zones.

  11. Study on contaminant mass removal by soil vapor extraction

    NASA Astrophysics Data System (ADS)

    Fen, Chiu-Shia

    2015-04-01

    Soil vapor extraction (SVE) is an effective remediation technology for removal of volatile organic compounds (VOCs) in unsaturated zones, particularly for high permeability soils. However, due to the nature of soil heterogeneities in most of the subsurface systems, the performance of SVE systems may be affected. Radius of influence (ROI) is usually evaluated at sites by measuring vacumm pressures of subsurface systems or through judging from the magnitudes of soil permeabilities. Within the area of a ROI, it is usually believed that the vaporized VOCs can be effectively removed from soil pores. Besides, it has been discussed whether continuous or pulsed venting operations is efficient for contaminant mass removal. The purpose of this study is to assess the relationships of subsurface vacuum pressure, pore gas velocity and contaminant mass removal rate from a venting well. A multiphase flow and multicompositional contaminant transport model will be applied to various scenarios of soil heterogeneities with different strategies of venting operation. We are, in an attempt, to find out controlling factors affecting the efficiency of contaminant mass removal from a venting well.

  12. How to Use Removable Mass Storage Memory Devices

    ERIC Educational Resources Information Center

    Branzburg, Jeffrey

    2004-01-01

    Mass storage refers to the variety of ways to keep large amounts of information that are used on a computer. Over the years, the removable storage devices have grown smaller, increased in capacity, and transferred the information to the computer faster. The 8" floppy disk of the 1960s stored 100 kilobytes, or about 60 typewritten, double-spaced…

  13. Removal of the samarium isobaric interference from promethium mass analysis

    SciTech Connect

    Shaw, R.W.; Young, J.P.; Smith, D.H.

    1988-02-01

    Resonance ionization mass spectroscopy (RIMS) is used to eliminate isobaric interference when determining the isotopic abundances of an element. In this application, RIMS is applied to the determination of promethium with the removal of samarium interference. In particular, promethium-147 is separated form samarium-147 and samarium-152.

  14. High-Resolution Experiments on chemical oxidation of DNAPL in variable-aperture fractures: Delineation of three time regimes

    NASA Astrophysics Data System (ADS)

    Arshadi, M.; Rajaram, H.; Detwiler, R. L.; Jones, T.

    2013-12-01

    formed a thin layer between the TCE blobs and the glass surfaces. The images from the experiments indicate that the blobs in the upstream do not disappear or break up as fast as the other TCE blobs during the experiment. The results of total mass transfer rate from DNAPL blobs for all three experiments exhibit three distinct time regimes. The total rate of mass transfer from free phase DNAPL is smaller at early time and increases as permanganate propagates into the fracture and occupies more fraction of the cell. The duration of this early time regime depends on the permanganate flow rate and initial TCE distribution within the fracture. During the intermediate time regime when the available volume of the fracture has almost filled with permanganate, the large TCE blobs start to break up into smaller blobs. Relatively High and constant total mass transfer rates are observed during this time regime. With time, MnO2 precipitation in the fracture leads to changes in the aperture field and flow field. Precipitated MnO2 around TCE blobs also decreases the DNAPL accessible surface area, resulting in a decline in total mass transfer rate during the late time regime. The effects of large scale parameters, such as flow rate, permanganate inflow concentration and initial TCE distribution on processes of DNAPL remediation will also be discussed in this work.

  15. AN EXPERIMENTAL ASSESSMENT OF THE IMPACTS OF PARTIAL DNAPL SOURCE ZONE DELETION USING SPARGING AS A REMEDIATION TECHNIQUE

    EPA Science Inventory

    The contamination of the subsurface environment by dense non-aqueous phase liquids (DNAPL) is a wide-spread problem that poses a significant threat to soil and groundwater quality. Implementing different remediation techniques can lead to the removal of a high fraction of the DNA...

  16. AN EXPERIMENTAL ASSESSMENT OF THE IMPACTS OF PARTIAL DNAPL SOURCE ZONE DELETION USING SPARGING AS A REMEDIATION TECHNIQUE

    EPA Science Inventory

    The contamination of the subsurface environment by dense non-aqueous phase liquids (DNAPL) is a wide-spread problem that poses a significant threat to soil and groundwater quality. Implementing different remediation techniques can lead to the removal of a high fraction of the DNA...

  17. Removal of detergents from protein digests for mass spectrometry analysis

    PubMed Central

    Yeung, Yee-Guide; Nieves, Edward; Angeletti, Ruth; Stanley, E. Richard

    2008-01-01

    Detergents are commonly used for the extraction of hydrophobic proteins and must be removed for sensitive detection of peptides by mass spectrometry (MS). We demonstrate that ethyl acetate (EA) is able to extract octylglycoside (OG) from a protease digest without loss of peptides or interference with the MS peptide spectral profile. EA extraction was also found to reduce interference of SDS, NP-40 or Triton X-100 in the MS analysis. PMID:18713617

  18. MASS-REMOVAL AND MASS-FLUX-REDUCTION BEHAVIOR FOR IDEALIZED SOURCE ZONES WITH HYDRAULICALLY POORLY-ACCESSIBLE IMMISCIBLE LIQUID

    SciTech Connect

    Brusseau, M. L.; Difilippo, Erica L.; marble, justin C.; Oostrom, Mart

    2008-04-01

    A series of flow-cell experiments was conducted to investigate aqueous dissolution and mass-removal behavior for systems wherein immiscible liquid was non-uniformly distributed in physically heterogeneous source zones. The study focused specifically on characterizing the relationship between mass flux reduction and mass removal for systems for which immiscible liquid is poorly accessible to flowing water. Two idealized scenarios were examined, one wherein immiscible liquid at residual saturation exists within a lower-permeability unit residing in a higher-permeability matrix, and one wherein immiscible liquid at higher saturation (a pool) exists within a higher-permeability unit adjacent to a lower-permeability unit. The results showed that significant reductions in mass flux occurred at relatively moderate mass-removal fractions for all systems. Conversely, minimalmass flux reduction occurred until a relatively large fraction of mass (>80%) was removed for the control experiment, which was designed to exhibit ideal mass removal. In general, mass flux reduction was observed to follow an approximately one-to-one relationship with mass removal. Two methods for estimating mass-flux-reduction/mass-removal behavior, one based on system-indicator parameters (ganglia-to-pool ratio) and the other a simple mass-removal function, were used to evaluate the measured data. The results of this study illustrate the impact of poorly accessible immiscible liquid on mass-removal and mass-flux processes, and the difficulties posed for estimating mass-flux-reduction/mass-removal behavior.

  19. Summary of the research methods of DNAPL-water interfacial area and DNAPL saturation in porous media

    NASA Astrophysics Data System (ADS)

    Li, M.; Wan, L.

    2016-12-01

    The dense non-aqueous phase liquid (DNAPL)-water interfacial area and DNAPL saturation are key factors in groundwater pollution remediation. The research methods of DNAPL-water interfacial area were summarized, including interfacial partitioning tracer tests, synchrotron X-ray microtomography and theoretical models, and the disparity of the study results with different methods was analyzed. The applications of DNAPL saturation measurement methods including tracer test method, light transmission visualization (LTV) and electrical resistivity tomography (ERT) were also summarized, especially the current applications of light transmission method in China. The partitioning tracer test, as an important method in the study of correlation between DNAPL-water interfacial areas and DNAPL saturation for porous media systems, should be given more attention in laboratory and field experiments.

  20. DNAPL Source Zone Depletion During In Situ Chemical Oxidation (ISCO): Experimental and Modeling Studies

    DTIC Science & Technology

    2005-10-01

    Mines Park Soil (Seitz 2004) .............................. 25 Figure 2.4: Stagnant Film Model for DNAPL Dissolution Mass Transfer...considered the possibility that the multiple rates could be a result of organic carbon located within soil grain micropores being more difficult for...suggesting that either the proposed geometric configuration is not a rate-limiting factor or that reduced species in micropores are still

  1. CONTROLLED RELEASE, BLIND TEST OF DNAPL REMEDIATION BY ETHANOL FLUSHING

    EPA Science Inventory

    A dense nonaqueous phase liquid (DNAPL) source zone was established within a sheet-pile
    isolated cell through a controlled release of perchloroethylene (PCE) to evaluate DNAPL
    remediation by in-situ cosolvent flushing. Ethanol was used as the cosolvent, and the main remedia...

  2. CONTROLLED RELEASE, BLIND TEST OF DNAPL REMEDIATION BY ETHANOL FLUSHING

    EPA Science Inventory

    A dense nonaqueous phase liquid (DNAPL) source zone was established within a sheet-pile
    isolated cell through a controlled release of perchloroethylene (PCE) to evaluate DNAPL
    remediation by in-situ cosolvent flushing. Ethanol was used as the cosolvent, and the main remedia...

  3. Field test of single well DNAPL characterization using alcohol injection/extraction

    SciTech Connect

    Jerome, K.M.; Looney, B.B.; Rhoden, M.L.; Riha, B.; Burdick, S.

    1996-10-29

    Soils and groundwater beneath an abandoned process sewer line in the A/M Area of the Savannah River Site (SRS) contain elevated levels of volatile organic compounds, specifically trichloroethylene (TCE) and tetrachloroethylene (PCE), two common chlorinated solvents. These compounds have low aqueous solubilities, thus when released to the subsurface in sufficient quantity, tend to exist as immiscible fluids or nonaqueous phase liquids (NAPLs). Because chlorinated solvents are also denser than water, they are referred to by the acronym DNAPLs, or dense non-aqueous phase liquids. Technologies targeted at efficient characterization or removal of DNAPL are not currently proven. The authors performed injection/extraction characterization tests in six existing wells in A/M Area. Water concentrations for TCE and/or PCE in these wells ranged from 0% to 100% of solubility. For each test, small amounts of solubilizing solution were used to try to confirm or deny the presence or absence of DNAPL in the immediate vicinity of the well screen.

  4. Retroauricular hairline incision for removal of upper neck masses.

    PubMed

    Roh, Jong-Lyel

    2005-12-01

    The general population has been increasingly concerned about cosmesis and hopeless about prominent or invisible postoperative scars of the face and neck. The purpose of this study was to evaluate the benefit of a retroauricular hairline incision (RAHI) by comparing it with conventional cervical incision for removal of upper neck masses. Prospective clinical study. Thirty-four patients with upper neck masses were divided into two surgical groups of RAHI (17) and conventional cervical incision (17) matched by age, sex, marital status and size, location, pathology of lesions. The operation time, complications, length of hospital stay, and subjective satisfaction with incision scar checked by visual analogue scale were compared between groups. The lesions of each group were congenital cysts (6), abscesses (2), inflammatory masses (2), and benign (6) or malignant (1) tumors and located in the upper neck. Mean operation time was 51 +/- 17 minute in the RAHI group and 41 +/- 13 minutes in the controls (P = .064). Mean hospital stay and complication rates were comparable between groups. Mean score of patient's satisfaction was 8.9 +/- 0.7 in the RAHI group and 4.5 +/- 2.7 in the controls (P < .001). The degree of incision scarring did not differ between groups, but the scars were less visible in the RAHI group because of hiding by the auricle and hair. The postauricular approach leading to a potentially invisible area of operation has a clear cosmetic benefit compared with conventional cervical incision. This will be helpful for patients with surgically indicated upper neck masses who hope for invisible incision scars.

  5. FIELD EVALUATION OF THE TREATMENT OF DNAPL USING EMULSIFIED ZERO-VALENT IRON (DNAPL CONFERENCE)

    EPA Science Inventory

    A pilot scale field demonstration of dense non-aqueous phase liquids (DNAPL) treatment using emulsified zero-valent iron (EZVI) is being conducted at Parris Island Marine Corps Recruit Depot (MCRD), Parris Island SC. The demonstration is being conducted by Geosyntec, the Nationa...

  6. FIELD EVALUATION OF THE TREATMENT OF DNAPL USING EMULSIFIED ZERO-VALENT IRON (DNAPL CONFERENCE)

    EPA Science Inventory

    A pilot scale field demonstration of dense non-aqueous phase liquids (DNAPL) treatment using emulsified zero-valent iron (EZVI) is being conducted at Parris Island Marine Corps Recruit Depot (MCRD), Parris Island SC. The demonstration is being conducted by Geosyntec, the Nationa...

  7. In-situ control of DNAPL density using polyaphrons.

    PubMed

    Le, Yan; Thompson, Karsten E; Valsaraj, Kalliat T; Reible, Danny D

    2003-10-01

    Once spilled into soils, dense nonaqueous phase liquids (DNAPLs) such as chlorinated solvents migrate deep into the subsurface because of their high density. Their downward migration typically continues until capillary forces balance gravitational forces or until essentially impermeable strata are reached. Efforts to mobilize the DNAPL for remediation purposes risks driving the contaminants deeper, which has spurred research for modifying buoyancy forces in situ. In this paper, a novel means of controlling the density of a DNAPL phase using polyaphrons is presented. Polyaphrons are a class of high internal phase ratio emulsions (HIPREs) that have unusual properties such as indefinite stability and flow properties through porous media. They provide a means of selectively delivering a light organic phase liquid to the vicinity of the DNAPL phase. Upon destabilization of the polyaphron by a polyvalent cation, the light internal phase mixes with the DNAPL to produce a nonaqueous phase of lower density than the original contaminant. The negative buoyancy of the DNAPL can thus be reversed. This approach holds great promise for manipulating DNAPL densities prior to or during remediation treatments.

  8. DNAPL Surface Chemistry: Its Impact on DNAPL Distribution in the Vadose Zone and its Manipulation to Enhance Remediation

    SciTech Connect

    Powers, Susan E.; Grimberg, Stefan; Denham, Miles E.; Borkovec, Michal

    2001-06-01

    The primary hypothesis of this work is that surface-active chemicals and/or microorganisms present in the unsaturated zone can significantly alter interfacial phenomena governing the migration of DNAPLs, thereby affecting the accessibility of a DNAPL during remediation efforts. The surface-active materials are present in complex NAPL mixtures and are produced through microbial metabolic processes. The overall goal of this proposed research is to understand the role of and changes in interfacial phenomena on the accessibility of DNAPL in the vadose zone.

  9. DNAPL Surface Chemistry: Its Impact on DNAPL Distribution in the Vadose Zone and its Manipulation to Enhance Remediation

    SciTech Connect

    Powers, Susan E.; Grimberg, Stefan; Denham, Miles E.; Borkovec, Michal

    2002-06-01

    The primary hypothesis of this work is that surface-active chemicals and/or microorganisms present in the unsaturated zone can significantly alter interfacial phenomena governing the migration of DNAPLs, thereby affecting the accessibility of a DNAPL during remediation efforts. The surface-active materials are present in complex NAPL mixtures and are produced through microbial metabolic processes. The overall goal of this proposed research is to understand the role of and changes in interfacial phenomena on the accessibility of DNAPL in the vadose zone.

  10. The fundamentals and futures of removable mass storage alternatives

    NASA Technical Reports Server (NTRS)

    Kempster, Linda

    1993-01-01

    This article reflects my view of how the storage products have been introduced into the marketplace, where they came from, and where others will continue to come from in the future. My corporate goal is to be a resource for those searching for removable solutions to mass storage problems. My introduction to optical storage occurred a few months before signing a non-disclosure agreement with FileNet on 8 Aug. 1983. By 87 or 88, as the optical craze was getting more popular, I started looking for similar or complementary storage technologies. I am still looking and my research is constantly turning up new entrants into this field. Due to the scope of the coverage in this field, this article does not dwell on any single technology. The goal is to provide information that is not compiled in any other single source and focus on facts that are not commonly known. I have provided a few baseline assumptions to ensure the mathematical calculations remain consistent: (1) hard-copy 8.5 in x 11 in documents which are scanned at 200 dots per inch (dpi) and compressed at a ratio of 10:1 result in a document image which requires an average of 50 Kilobytes (KB) of storage; (2) an average ASCII page requires 2 KB of storage; (3) an average flle cabinet drawer can hold 2500 pieces of paper; (4) one GB of storage can hold an average of 20,000 document images (a reel of 6250 tape holds 180 Megabytes (MB)).

  11. The fundamentals and futures of removable mass storage alternatives

    NASA Technical Reports Server (NTRS)

    Kempster, Linda

    1993-01-01

    This article reflects my view of how the storage products have been introduced into the marketplace, where they came from, and where others will continue to come from in the future. My corporate goal is to be a resource for those searching for removable solutions to mass storage problems. My introduction to optical storage occurred a few months before signing a non-disclosure agreement with FileNet on 8 Aug. 1983. By 87 or 88, as the optical craze was getting more popular, I started looking for similar or complementary storage technologies. I am still looking and my research is constantly turning up new entrants into this field. Due to the scope of the coverage in this field, this article does not dwell on any single technology. The goal is to provide information that is not compiled in any other single source and focus on facts that are not commonly known. I have provided a few baseline assumptions to ensure the mathematical calculations remain consistent: (1) hard-copy 8.5 in x 11 in documents which are scanned at 200 dots per inch (dpi) and compressed at a ratio of 10:1 result in a document image which requires an average of 50 Kilobytes (KB) of storage; (2) an average ASCII page requires 2 KB of storage; (3) an average flle cabinet drawer can hold 2500 pieces of paper; (4) one GB of storage can hold an average of 20,000 document images (a reel of 6250 tape holds 180 Megabytes (MB)).

  12. FIELD EVALUATION OF DNAPL EXTRACTION TECHNOLOGIES: PROJECT OVERVIEW

    EPA Science Inventory

    Five DNAPL remediation technologies were evaluated at the Dover National Test Site, Dover AFB, Delaware. The technologies were cosolvent solubilization, cosolvent mobilization, surfactant solubilization, complex sugar flushing and air sparging/soil vapor extraction. The effectiv...

  13. FIELD EVALUATION OF DNAPL EXTRACTION TECHNOLOGIES: PROJECT OVERVIEW

    EPA Science Inventory

    Five DNAPL remediation technologies were evaluated at the Dover National Test Site, Dover AFB, Delaware. The technologies were cosolvent solubilization, cosolvent mobilization, surfactant solubilization, complex sugar flushing and air sparging/soil vapor extraction. The effectiv...

  14. Applying Bioaugmentation to Treat DNAPL Sources in Fractured Rock

    DTIC Science & Technology

    2017-03-27

    GUIDANCE DOCUMENT Applying Bioaugmentation to Treat DNAPL Sources in Fractured Rock ESTCP Project ER-201210 MARCH 2017 Charles Schaefer, Ph.D...12-C-0062 Applying Bioaugmentation to Treat DNAPL Sources in Fractured Rock 5b. GRANT NUMBER NA 5c. PROGRAM ELEMENT NUMBER NA 6. AUTHOR(S...Approved for Public Release, Distribution is Unlimited 13. SUPPLEMENTARY NOTES None 14. ABSTRACT Management of fractured rock sites impacted by

  15. Monitoring Genetic and Metabolic Potential for In-Site Bioremediation: Mass Spectrometry

    SciTech Connect

    Buchanan, M.V.

    2000-07-20

    A number of DOE sites are contaminated with mixtures of dense non-aqueous phase liquids (DNAPLs) such as carbon tetrachloride, chloroform, perchloroethylene, and trichloroethylene. At many of these sites, in situ microbial bioremediation is an attractive strategy for cleanup, since it has the potential to degrade DNAPLs in situ without the need for pump-and-treat or soil removal procedures, and without producing toxic byproducts. A rapid screening method to determine broad range metabolic and genetic potential for contaminant degradation would greatly reduce the cost and time involved in assessment for in situ bioremediation, as well as for monitoring ongoing bioremediation treatment. The objective of this project was the development of mass-spectrometry-based methods to screen for genetic potential for both assessment and monitoring of in situ bioremediation of DNAPLs. These methods were designed to provide more robust and routine methods for DNA-based characterization of the genetic potential of subsurface microbes for degrading pollutants. Specifically, we sought to (1) Develop gene probes that yield information equivalent to conventional probes, but in a smaller size that is more amenable to mass spectrometric detection, (2) Pursue improvements to matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) methodology in order to allow its more general application to gene probe detection, and (3) Increase the throughput of microbial characterization by integrating gene probe preparation, purification, and MALDI-MS analysis.

  16. Demonstration of a Fractured Rock Geophysical Toolbox (FRGT) for Characterization and Monitoring of DNAPL Biodegradation in Fractured Rock Aquifers

    DTIC Science & Technology

    2015-09-29

    parameters controlling mass transfer . For the amendment injection and DNAPL monitoring component of the toolkit, this project set out to investigate the...capacitance, and thus the properties of fluid-grain boundaries in porous media . Finally, it is possible to simply measure an open circuit potential of an...from the northeastern US. The team has also strived to take advantage of tech transfer activities via social media as promoted by ESTCP officials

  17. Transport with Bimolecular Reactions: Applications to In-Situ Chemical Oxidation of DNAPLs by Permanganate in Fractured Rock

    NASA Astrophysics Data System (ADS)

    Arshadi, Masoud

    Chemical oxidation of dense nonaqueous-phase liquids (DNAPLs) by permanganate has emerged as an effective remediation strategy in fractured rock. Our objectives in this research were to carry out a sequence of experimental, computational and theoretical tasks aimed at improving current understanding of permanganate oxidation in fractured rock systems, and also develop modeling tools that can be used for preliminary design of oxidation schemes at field sites. Our research focused on both free-phase entrapped DNAPL in variable-aperture fractures and dissolved DNAPL in the rock matrix. In the first section of our research, we present high-resolution experimental investigations in transparent analog variable-aperture fractures to improve understanding of chemical oxidation of residual entrapped trichloroethylene (TCE) in fractures. Four experiments were performed with different permanganate concentrations, flow rates, and initial TCE phase geometry. The initial aperture field and evolving entrapped-phase geometry were measured quantitatively. We present results on the time-evolution of fracture-scale TCE consumption and DNAPL removal rates for all the experiments. In the next part of this work, we developed theoretical understanding of the reaction front dynamics in the case of chemical oxidation of aqueous-phase DNAPL within fracture-matrix system, backed up by numerical simulations. We also consider the influence of NOD consumption and contaminant sorption to solid aquifer materials in our models. Based on the results from this task we are able to propose simple strategies for remediation design (e.g. the time needed to degrade DNAPL inside the fracture-matrix system and the permanganate injection pattern) for a given set of conditions. Our numerical simulations of diffusion with bimolecular reaction in the rock matrix demonstrated a transition in the spatially integrated reaction rate - increasing with time initially, and transitioning to a decrease with time. We

  18. Dnapl Site Remediation: Status and Research Needs (Invited)

    NASA Astrophysics Data System (ADS)

    Stroo, H. F.; Kueper, B. H.

    2013-12-01

    Remediation of sites impacted by dense, non-aqueous phase liquids (DNAPLs) such as chlorinated solvents remains technically challenging despite significant advances over the past 30 years. Contaminants are difficult to locate in the subsurface, and it is difficult to deliver remedial agents to the contamination effectively. If lower permeability media are present, these can act as diffusive sinks for aqueous and sorbed phase constituents, further complicating characterization and cleanup. DNAPL source zones are particularly difficult to remediate, and even after treatment these sources can persist for many decades, if not centuries, and it is difficult to transition sites to a passive management strategy. A recent expert panel on source zone remediation identified three overriding objectives for future remediation - to be more surgical, more sustainable, and more certain. Surgical remediation refers to precise delineation of contaminants and hydrogeology, with more targeted remediation efforts. Sustainable remediation refers to the growing need to consider all environmental impacts when developing remediation strategies, including energy use, greenhouse gas emissions, lifecycle impacts, and the increasing demand for clean water. Although considerable uncertainty is inherent in subsurface remediation, there is potential to reduce this uncertainty through improved monitoring and modeling. Specific characterization and remediation needs will be summarized separately. Improved technologies for source characterization are critical because inadequate characterization is common given the costs and limitations of current techniques. As a result, the performance of field-scale remediation technologies is frequently disappointing. Specific research needs to improve source zone characterization include: (i) better delineation and mass estimation, (ii) source zone architecture characterization methods, and (iii) increased resolution and fine-scale mapping of geologic

  19. Impact of enhanced-flushing reagents and organic-liquid distribution on mass removal and mass-discharge reduction

    PubMed Central

    Akyol, Nihat Hakan; Lee, Ann Russo; Brusseau, Mark L

    2014-01-01

    A series of column and flow-cell experiments was conducted to investigate the impact of non-uniform organic-liquid distribution on the relationship between reductions in contaminant mass discharge and reductions in source zone mass under conditions of enhanced-solubilization flushing. Trichloroethene was used as the model organic liquid, and SDS (sodium dodecyl sulfate) and ethanol were used as representative enhanced-flushing reagents. The results were compared to those of water-flood control experiments. Concentrations of trichloroethene in the effluent exhibited multi-step behavior with time, wherein multiple secondary periods of quasi steady state were observed. This non-ideal behavior was observed for both the water-flood and enhanced-flushing experiments. For all flow-cell experiments, the later stage of mass removal was controlled by the more poorly- accessible mass associated with higher-saturation zones. The profiles relating reductions in contaminant mass discharge and reductions in mass exhibited generally similar behavior for both the water-flood and enhanced-flushing experiments. This indicates that while the rates and magnitudes of mass removal are altered by the presence of a solubilization-reagent solution, the fundamental mass-removal process is not. The profiles obtained for the flow-cell systems differed from those obtained for the column systems, highlighting the impact of source-zone heterogeneity on mass-removal behavior. PMID:24563557

  20. Impact of enhanced-flushing reagents and organic-liquid distribution on mass removal and mass-discharge reduction.

    PubMed

    Akyol, Nihat Hakan; Lee, Ann Russo; Brusseau, Mark L

    2013-10-01

    A series of column and flow-cell experiments was conducted to investigate the impact of non-uniform organic-liquid distribution on the relationship between reductions in contaminant mass discharge and reductions in source zone mass under conditions of enhanced-solubilization flushing. Trichloroethene was used as the model organic liquid, and SDS (sodium dodecyl sulfate) and ethanol were used as representative enhanced-flushing reagents. The results were compared to those of water-flood control experiments. Concentrations of trichloroethene in the effluent exhibited multi-step behavior with time, wherein multiple secondary periods of quasi steady state were observed. This non-ideal behavior was observed for both the water-flood and enhanced-flushing experiments. For all flow-cell experiments, the later stage of mass removal was controlled by the more poorly- accessible mass associated with higher-saturation zones. The profiles relating reductions in contaminant mass discharge and reductions in mass exhibited generally similar behavior for both the water-flood and enhanced-flushing experiments. This indicates that while the rates and magnitudes of mass removal are altered by the presence of a solubilization-reagent solution, the fundamental mass-removal process is not. The profiles obtained for the flow-cell systems differed from those obtained for the column systems, highlighting the impact of source-zone heterogeneity on mass-removal behavior.

  1. A media maniac's guide to removable mass storage media

    NASA Technical Reports Server (NTRS)

    Kempster, Linda S.

    1996-01-01

    This paper addresses at a high level, the many individual technologies available today in the removable storage arena including removable magnetic tapes, magnetic floppies, optical disks and optical tape. Tape recorders represented below discuss logitudinal, serpantine, logitudinal serpantine,and helical scan technologies. The magnetic floppies discussed will be used for personal electronic in-box applications.Optical disks still fill the role for dense long-term storage. The media capacities quoted are for native data. In some cases, 2 KB ASC2 pages or 50 KB document images will be referenced.

  2. DNAPLs at DOE sites: Background and assessment of characterization technologies

    SciTech Connect

    Junk, G.A.; Haas, W.J. Jr.

    1993-12-01

    The Characterization, Monitoring, and Sensor Technology Integrated Program (CMST-IP) within the Office of Technology Development (OTD) has responsibility for identification, evaluation, and delivery of technologies needed for the work of the Department of Energy`s Office of Environmental Restoration and Waste Management. This report addresses part of that responsibility by providing summary information on DNAPL site characterization. A dense nonaqueous phase liquid (DNAPL) is a source of contamination that can persist in the subsurface for decades before dissipating completely into the vapor phase and groundwater. The DNAPL chemicals of particular concern to the DOE are chlorinated volatile organic compounds (Cl VOCS) such as carbon tetrachloride (CCl{sub 4}), trichloroethylene (TCE), and perchloroethylene (PCE). These Cl VOCs were used in multiple ton quantities at DOE sites and were often released to the subsurface. The predicted fate of released Cl VOC liquid is downward movement through the soil under the force of gravity. As it moves, some of the Cl VOC liquid becomes trapped in the soil pores as residual saturation. The liquid also moves rapidly downward if small fractures are present. This migration continues until an impermeable or semi-permeable layer is encountered. Then lateral movement or spreading occurs. The downward and lateral migration in the subsurface leads to DNAPL pools, lenses, and residual saturation that can cause long-term contamination of groundwater at levels well above drinking water standards. Although Cl VOCs have been detected as dissolved components in the groundwater and as vapor in the soil gas at several DOE sites, direct evidence of their presence as DNAPL is sparse and no measurements of the amounts of DNAPL present within a given volume of subsurface have been made. Consequently, unresolved DNAPL issues exist at DOE sites.

  3. Steam and ET-DSP combined for DNAPL remediation: full-scale site restoration at Young-Rainey Star Center

    SciTech Connect

    Heron, Gorm; Carroll, Steven; Sowers, Hank; McGee, Bruce; Juhlin, Randall; Daniel, Joe; Ingle, David S.

    2004-05-01

    In March of 2003, the United States Department of Energy (DOE) completed a full-scale nonaqueous-phase liquid (NAPL) remediation of Area A of the Northeast Site at the Young-Rainey STAR Center, Largo, Florida. The site was contaminated with approximately 2,300 kg (5,000 lbs) of NAPL constituents such as TCE, cis-1,2-DCE, methylene chloride, toluene, and petroleum hydrocarbons. The site was remediated by SteamTech using a combination of steam-enhanced extraction and electrical resistance heating during operations lasting 4.5 months. After the target volume had been heated to or near boiling temperatures, pressure cycles were used to increase the mass removal rates. Each de-pressurization cycle led to large increases in the vapor phase recovery, until a final phase of diminishing returns was reached. Post-operational sampling at randomly selected locations showed the concentrations of all contaminants of concern (COC) to be well below the remedial goals. The majority of the groundwater samples were below maximum contaminant level (MCL) for all the contaminants of concern. The overall mass balance showed that about 0.5 kg (1 pound) of VOCs remained in the remedial volume, and showed remedial efficiencies of between 99.85 and 99.99 percent for the four chemicals of concern. This is the first full-scale demonstration of complete source removal at a DNAPL site. Since the post-operational sampling shows all concentrations to be below or close to groundwater MCLs, the thermal remedy may be satisfactory for site closure without a polishing phase.

  4. Phase I Field Test Results of an Innovative DNAPL Remediation Technology: The Hydrophobic Lance

    SciTech Connect

    Tuck, D.M.

    1999-01-28

    An innovative technology for recovery of pure phase DNAPL was deployed in the subsurface near the M-Area Settling Basin, continuing the support of the A/M Area Ground Water Corrective Action Program (per Part B requirements). This technology, the Hydrophobic Lance, operates by placing a neutral/hydrophobic surface (Teflon) in contact with the DNAPL. This changes the in situ conditions experienced by the DNAPL, allowing it to selectively drain into a sump from which it can be pumped. Collection of even small amounts of DNAPL can save years of pump-and-treat operation because of the generally low solubility of DNAPL components.

  5. Timing of Bag Application and Removal in Controlled Mass Pollination

    Treesearch

    F.E. Bridgwater; D.L. Bramlett; V.D. Hipkins

    1999-01-01

    Controlled mass pollination (CMP) among outstanding parents is one way to increase genetic gains from traditional wind-pollinated seed orchards, but the economic success of CMP depends on both genetic gains and costs. CMP has been shown. to be cost-effective (Bridgwater et al. 1998) even when costs were adjusted for risk (Byram and Bridgwater 1999, These Proceedings...

  6. The Outcome of Supernovae in Massive Binaries; Removed Mass, and its Separation Dependence

    NASA Astrophysics Data System (ADS)

    Hirai, Ryosuke; Sawai, Hidetomo; Yamada, Shoichi

    2014-09-01

    The majority of massive stars are formed in binary systems. It is hence reasonable to expect that most core-collapse supernovae (CCSNe) take place in binaries and the existence of a companion star may leave some imprints in observed features. Having this in mind, we have conducted two-dimensional hydrodynamical simulations of the collisions of CCSNe ejecta with the companion star in an almost-equal-mass (~10 M ⊙) binary to find out possible consequences of such events. In particular we pay attention to the amount of mass removed and its dependence on the binary separation. In contrast to the previous surmise, we find that the companion mass is stripped not by momentum transfer but by shock heating. Up to 25% of the original mass can be removed for the closest separations and the removed mass decreases as M ubvpropa -4.3 with the binary separation a. By performing some experimental computations with artificially modified densities of incident ejecta, we show that if the velocity of ejecta is fixed, the density of incident ejecta is the single important parameter that actually determines the removed mass as Mub \\propto ρ ej 1.4. On the other hand, another set of simulations with modified velocities of incident ejecta demonstrate that the strength of the forward shock, which heats up the stellar material and causes the mass loss of the companion star, is actually the key parameter for the removed mass.

  7. Application of the UTCHEM simulator to DNAPL site characterization

    SciTech Connect

    Butler, G.W.

    1995-12-31

    Numerical simulation using the University of Texas Chemical Flood Simulator (UTCHEM) was used to evaluate two dense, nonaqueous phase liquid (DNAPL) characterization methods. The methods involved the use of surfactants and partitioning tracers to characterize a suspected trichloroethene (TCE) DNAPL zone beneath a US Air Force Plant in Texas. The simulations were performed using a cross-sectional model of the alluvial aquifer in an area that is believed to contain residual TCE at the base of the aquifer. Characterization simulations compared standard groundwater sampling, an interwell NAPL Solubilization Test, and an interwell NAPL Partitioning Tracer Test. The UTCHEM simulations illustrated how surfactants and partitioning tracers can be used to give definite evidence of the presence and volume of DNAPL in a situation where conventional groundwater sampling can only indicate the existence of the dissolved contaminant plume.

  8. Dual-well recovery system design for enhanced DNAPL production

    SciTech Connect

    Nazar, A.; Gray, D.; Oolman, T.

    1997-12-31

    An innovative recovery well system was designed and installed for the enhanced recovery of dense non-aqueous phase liquid, DNAPL (creosote) at an active wood treating facility which had historic releases of wood treating chemicals to soils and groundwater. The regulatory objective of the work, which is being conducted pursuant to a State RCRA Post-Closure Permit, is to implement interim measures for enhanced DNAPL recovery in the vicinity of the downgradient point of compliance (POC) of a 2-acre RCRA Regulated Unit. The RCRA-Regulated Unit consists of two closed former surface impoundments formerly used for wastewater treatment. The facility is underlain by coarsening downward sand and gravel deposits ranging in thickness from about 75 to 90 feet below ground surface (ft-bgs). DNAPL is present in both residual and mobile phases throughout the saturated zone from a depth of approximately 25 to 90 ft-bgs. The DNAPL has also accumulated on the top of a confining clay layer which underlies the alluvial sand and gravel deposits. Due to the physical nature of the subsurface materials and the presence of DNAPL, innovative recovery well installation and design practices were required to provide for the ability to enhance DNAPL recovery. The technology consists of a dual-well recirculating design contained within a singular, large diameter borehole. The design incorporated innovative practices in drilling and installation, screen slot sizing, and well construction, featuring a dual-well design. Conventional mud rotary drilling techniques were utilized with innovative equipment modifications and the use of a natural organic polymer drilling fluid additive to enhance overall recovery well efficiency and performance.

  9. Significance of nitrogen removal mass in uremic patients on different modalities of dialysis therapy.

    PubMed

    Chen, T W; Huang, T P; Wang, M L

    2000-02-01

    While most nephrologists use Kt/V values for dialysis prescriptions, some researchers are beginning to view the role of solute removal mass as an indicator of adequate dialysis. This study, using nitrogen as a surrogate for solute removal, probed whether solute removal mass can be used as the target of adequate dialysis. Mathematical formulas for easy bedside calculation of nitrogen removal mass were used to avoid the problems associated with direct measurement. The weekly removal mass of urea nitrogen (M) and the urea generation rate (G) of 32 conventional hemodialysis (HD) and 21 continuous ambulatory peritoneal dialysis (CAPD) patients were calculated. All the patients were anuric, clinically stable, and under adequate dialysis pursuant to either the criterion of the urea index, Kt/V, or clinical requirements. The difference in MHD (MHD = 41.9 +/- 9.5 g/week, MCAPD = 38.8 +/- 11.9 g/week) and G (GHD = 3.90 +/- 1.02 mg/min, GCAPD = 3.85 +/- 1.21 mg/min) between the two groups was statistically insignificant (p = 0.119 and p = 0.868, respectively). When protein nitrogen leaking through the peritoneal membrane was considered and added to MCAPD, nitrogen removal in CAPD patients (M'CAPD = 42.3 +/- 13.0 g/week) approached that in HD patients (p = 0.886). There was no correlation between dialysis dosage and urea removal mass in either the CAPD or HD groups. Urea nitrogen removal mass is similar to the protein catabolic rate (PCR) in stable patients. It is meaningful in dialysis evaluation only when it is used simultaneously with blood urea nitrogen measurement. However, because M changes at the inception of dialysis, it more significant than PCR in the evaluation of unstable patients.

  10. The effects of body mass on dung removal efficiency in dung beetles.

    PubMed

    Nervo, Beatrice; Tocco, Claudia; Caprio, Enrico; Palestrini, Claudia; Rolando, Antonio

    2014-01-01

    Understanding of the role of body mass in structural-functional relationships is pressing, particularly because species losses often occur non-randomly with respect to body size. Our study examined the effects of dung beetle body mass on dung removal at two levels. First, we used the lab experiment to evaluate the efficiency of eight dung beetle species belonging to two functional groups (tunnelers, dwellers) on dung removal. Second, the same species employed in the lab were used in field mesocosms to examine the effects of the two functional groups on dung removal maintaining realistic differences in the total body mass between tunneler and dweller assemblages. Furthermore, the experimental assemblages contained one and four species within each functional group, so the effect of body mass heterogeneity was examined. We used a statistical approach (offset method) which took into account a priori constraints due to the study design allowing us to analyse the effect of larger species in mesocosm style experiments. Body size played a crucial role in dung removal: large beetles were more efficient than small ones and the percentage of removed dung increased with higher body mass heterogeneity. Tunnelers were more efficient than dwellers over both short and long time periods (one month and one year). Significant effects of dwellers were found only after one year. Moreover, our study showed that not including the body mass as an offset in the model resulted in sometimes different results, as the offset expresses dung removal independently of the body mass. This approach confirmed that body size is likely a pivotal factor controlling dung removal efficiency at multiple levels, from single species to overall dung beetle assemblages. Even though other specific traits should be examined, this study has begun to address the consequences of losing individuals with specific traits that are especially sensitive to perturbations.

  11. The Effects of Body Mass on Dung Removal Efficiency in Dung Beetles

    PubMed Central

    Nervo, Beatrice; Tocco, Claudia; Caprio, Enrico; Palestrini, Claudia; Rolando, Antonio

    2014-01-01

    Understanding of the role of body mass in structural-functional relationships is pressing, particularly because species losses often occur non-randomly with respect to body size. Our study examined the effects of dung beetle body mass on dung removal at two levels. First, we used the lab experiment to evaluate the efficiency of eight dung beetle species belonging to two functional groups (tunnelers, dwellers) on dung removal. Second, the same species employed in the lab were used in field mesocosms to examine the effects of the two functional groups on dung removal maintaining realistic differences in the total body mass between tunneler and dweller assemblages. Furthermore, the experimental assemblages contained one and four species within each functional group, so the effect of body mass heterogeneity was examined. We used a statistical approach (offset method) which took into account a priori constraints due to the study design allowing us to analyse the effect of larger species in mesocosm style experiments. Body size played a crucial role in dung removal: large beetles were more efficient than small ones and the percentage of removed dung increased with higher body mass heterogeneity. Tunnelers were more efficient than dwellers over both short and long time periods (one month and one year). Significant effects of dwellers were found only after one year. Moreover, our study showed that not including the body mass as an offset in the model resulted in sometimes different results, as the offset expresses dung removal independently of the body mass. This approach confirmed that body size is likely a pivotal factor controlling dung removal efficiency at multiple levels, from single species to overall dung beetle assemblages. Even though other specific traits should be examined, this study has begun to address the consequences of losing individuals with specific traits that are especially sensitive to perturbations. PMID:25229237

  12. Impact of enhanced-flushing reagents and organic-liquid distribution on mass removal and mass-flux reduction

    NASA Astrophysics Data System (ADS)

    Akyol, N. H.; Russo, A. E.; Brusseau, M. L.

    2011-12-01

    A series of flow-cell experiments was conducted to investigate the impact of nonuniform organic-liquid distribution and flow-field heterogeneity on the relationship between source zone mass removal and mass flux reduction under conditions of enhanced-solubilization flushing. Sudan IV dyed trichloroethene was used as the model organic liquid, and SDS (sodium dodecyl sulfate) and ethanol were used as representative enhanced-flushing reagents. The results were compared to those of water-flood control experiments. Natural sand media with different median particle diameters and natural soils were used for these experiments to represent various pyhsically heterogeneous systems. Photographs were obtained throughout the course of the experiments to observe changes in source-zone distributions. The results showed that the heterogeneous systems exhibited multi-step mass-flux reduction/mass-removal behavior. This nonideal behavior was observed for both the water-flood and enhanced-flushing experiments. For all cases, the later stage of mass removal was controlled by the more poorly-accessible mass associated with higher-saturation zones.

  13. Synergistic, ultrafast mass storage and removal in artificial mixed conductors

    NASA Astrophysics Data System (ADS)

    Chen, Chia-Chin; Fu, Lijun; Maier, Joachim

    2016-08-01

    Mixed conductors—single phases that conduct electronically and ionically—enable stoichiometric variations in a material and, therefore, mass storage and redistribution, for example, in battery electrodes. We have considered how such properties may be achieved synergistically in solid two-phase systems, forming artificial mixed conductors. Previously investigated composites suffered from poor kinetics and did not allow for a clear determination of such stoichiometric variations. Here we show, using electrochemical and chemical methods, that a melt-processed composite of the ‘super-ionic’ conductor RbAg4I5 and the electronic conductor graphite exhibits both a remarkable silver excess and a silver deficiency, similar to those found in single-phase mixed conductors, even though such behaviour is not possible in the individual phases. Furthermore, the kinetics of silver uptake and release is very fast. Evaluating the upper limit set by interfacial ambipolar diffusion reveals chemical diffusion coefficients that are even higher than those achieved for sodium chloride in bulk liquid water. These results could potentially stimulate systematic research into powerful, even mesoscopic, artificial mixed conductors.

  14. Occurrence of pharmaceuticals in a municipal wastewater treatment plant: mass balance and removal processes.

    PubMed

    Gao, Pin; Ding, Yunjie; Li, Hui; Xagoraraki, Irene

    2012-06-01

    Occurrence and removal efficiencies of fifteen pharmaceuticals were investigated in a conventional municipal wastewater treatment plant in Michigan. Concentrations of these pharmaceuticals were determined in both wastewater and sludge phases by a high-performance liquid chromatograph coupled to a tandem mass spectrometer. Detailed mass balance analysis was conducted during the whole treatment process to evaluate the contributing processes for pharmaceutical removal. Among the pharmaceuticals studied, demeclocycline, sulfamerazine, erythromycin and tylosin were not detected in the wastewater treatment plant influent. Other target pharmaceuticals detected in wastewater were also found in the corresponding sludge phase. The removal efficiencies of chlortetracycline, tetracycline, sulfamerazine, acetaminophen and caffeine were >99%, while doxycycline, oxytetracycline, sulfadiazine and lincomycin exhibited relatively lower removal efficiencies (e.g., <50%). For sulfamethoxazole, the removal efficiency was approximately 90%. Carbamazepine manifested a net increase of mass, i.e. 41% more than the input from the influent. Based on the mass balance analysis, biotransformation is believed to be the predominant process responsible for the removal of pharmaceuticals (22% to 99%), whereas contribution of sorption to sludge was relatively insignificant (7%) for the investigated pharmaceuticals.

  15. Assessing the joint impact of DNAPL source-zone behavior and degradation products on the probabilistic characterization of human health risk

    NASA Astrophysics Data System (ADS)

    Henri, Christopher V.; Fernàndez-Garcia, Daniel; de Barros, Felipe P. J.

    2016-02-01

    The release of industrial contaminants into the subsurface has led to a rapid degradation of groundwater resources. Contamination caused by Dense Non-Aqueous Phase Liquids (DNAPLs) is particularly severe owing to their limited solubility, slow dissolution and in many cases high toxicity. A greater insight into how the DNAPL source zone behavior and the contaminant release towards the aquifer impact human health risk is crucial for an appropriate risk management. Risk analysis is further complicated by the uncertainty in aquifer properties and contaminant conditions. This study focuses on the impact of the DNAPL release mode on the human health risk propagation along the aquifer under uncertain conditions. Contaminant concentrations released from the source zone are described using a screening approach with a set of parameters representing several scenarios of DNAPL architecture. The uncertainty in the hydraulic properties is systematically accounted for by high-resolution Monte Carlo simulations. We simulate the release and the transport of the chlorinated solvent perchloroethylene and its carcinogenic degradation products in randomly heterogeneous porous media. The human health risk posed by the chemical mixture of these contaminants is characterized by the low-order statistics and the probability density function of common risk metrics. We show that the zone of high risk (hot spot) is independent of the DNAPL mass release mode, and that the risk amplitude is mostly controlled by heterogeneities and by the source zone architecture. The risk is lower and less uncertain when the source zone is formed mostly by ganglia than by pools. We also illustrate how the source zone efficiency (intensity of the water flux crossing the source zone) affects the risk posed by an exposure to the chemical mixture. Results display that high source zone efficiencies are counter-intuitively beneficial, decreasing the risk because of a reduction in the time available for the production

  16. Zero-Valent Metal Emulsion for Reductive Dehalogenation of DNAPLS

    NASA Technical Reports Server (NTRS)

    Reinhart, Debra R. (Inventor); Clausen, Christian (Inventor); Geiger, Cherie L. (Inventor); Quinn, Jacqueline (Inventor); Brooks, Kathleen (Inventor)

    2003-01-01

    A zero-valent metal emulsion is used to dehalogenate solvents, such as pooled dense non-aqueous phase liquids (DNAPLs), including trichloroethylene (TCE). The zero-valent metal emulsion contains zero-valent metal particles, a surfactant, oil and water. The preferred zero-valent metal particles are nanoscale and microscale zero-valent iron particles

  17. Zero-Valent Metal Emulsion for Reductive Dehalogenation of DNAPLs

    NASA Technical Reports Server (NTRS)

    Reinhart, Debra R. (Inventor); Clausen, Christian (Inventor); Gelger, Cherie L. (Inventor); Quinn, Jacqueline (Inventor); Brooks, Kathleen (Inventor)

    2006-01-01

    A zero-valent metal emulsion is used to dehalogenate solvents, such as pooled dense non-aqueous phase liquids (DNAPLs), including trichloroethylene (TCE). The zero-valent metal emulsion contains zero-valent metal particles, a surfactant, oil and water, The preferred zero-valent metal particles are nanoscale and microscale zero-valent iron particles.

  18. SIMULATION OF DNAPL DISTRIBUTION RESULTING FROM MULTIPLE SOURCES

    EPA Science Inventory

    A three-dimensional and three-phase (water, NAPL and gas) numerical simulator, called NAPL, was employed to study the interaction between DNAPL (PCE) plumes in a variably saturated porous media. Several model verification tests have been performed, including a series of 2-D labo...

  19. SIMULATION OF DNAPL DISTRIBUTION RESULTING FROM MULTIPLE SOURCES

    EPA Science Inventory

    A three-dimensional and three-phase (water, NAPL and gas) numerical simulator, called NAPL, was employed to study the interaction between DNAPL (PCE) plumes in a variably saturated porous media. Several model verification tests have been performed, including a series of 2-D labo...

  20. THE IMPACT OF PARTIAL DNAPL SOURCE ZONE REMEDIATION

    EPA Science Inventory

    Dense non-aqueous phase liquids (DNAPL) constitute a long-term source of groundwater contamination and a significant effort is usually required to treat these contaminated waters and bring them back to maximum contaminant level (MCL) required by the regulatory authorities.
    Fi...

  1. Zero-Valent Metal Emulsion for Reductive Dehalogenation of DNAPLS

    NASA Technical Reports Server (NTRS)

    Reinhart, Debra R. (Inventor); Clausen, Christian (Inventor); Geiger, Cherie L. (Inventor); Quinn, Jacqueline (Inventor); Brooks, Kathleen (Inventor)

    2003-01-01

    A zero-valent metal emulsion is used to dehalogenate solvents, such as pooled dense non-aqueous phase liquids (DNAPLs), including trichloroethylene (TCE). The zero-valent metal emulsion contains zero-valent metal particles, a surfactant, oil and water. The preferred zero-valent metal particles are nanoscale and microscale zero-valent iron particles

  2. THE IMPACT OF PARTIAL DNAPL SOURCE ZONE REMEDIATION

    EPA Science Inventory

    Dense non-aqueous phase liquids (DNAPL) constitute a long-term source of groundwater contamination and a significant effort is usually required to treat these contaminated waters and bring them back to maximum contaminant level (MCL) required by the regulatory authorities.
    Fi...

  3. The outcome of supernovae in massive binaries; removed mass, and its separation dependence

    SciTech Connect

    Hirai, Ryosuke; Sawai, Hidetomo; Yamada, Shoichi

    2014-09-01

    The majority of massive stars are formed in binary systems. It is hence reasonable to expect that most core-collapse supernovae (CCSNe) take place in binaries and the existence of a companion star may leave some imprints in observed features. Having this in mind, we have conducted two-dimensional hydrodynamical simulations of the collisions of CCSNe ejecta with the companion star in an almost-equal-mass (∼10 M {sub ☉}) binary to find out possible consequences of such events. In particular we pay attention to the amount of mass removed and its dependence on the binary separation. In contrast to the previous surmise, we find that the companion mass is stripped not by momentum transfer but by shock heating. Up to 25% of the original mass can be removed for the closest separations and the removed mass decreases as M {sub ub}∝a {sup –4.3} with the binary separation a. By performing some experimental computations with artificially modified densities of incident ejecta, we show that if the velocity of ejecta is fixed, the density of incident ejecta is the single important parameter that actually determines the removed mass as M{sub ub}∝ρ{sub ej}{sup 1.4}. On the other hand, another set of simulations with modified velocities of incident ejecta demonstrate that the strength of the forward shock, which heats up the stellar material and causes the mass loss of the companion star, is actually the key parameter for the removed mass.

  4. The role of mass removal mechanisms in the onset of ns-laser induced plasma formation

    SciTech Connect

    Autrique, D.; Clair, G.; L'Hermite, D.; Alexiades, V.; Bogaerts, A.; Rethfeld, B.

    2013-07-14

    The present study focuses on the role of mass removal mechanisms in ns-laser ablation. A copper sample is placed in argon, initially set at standard pressure and temperature. Calculations are performed for a 6 ns laser pulse with a wavelength of 532 nm and laser fluences up to 10 J/cm{sup 2}. The transient behavior in and above the copper target is described by a hydrodynamic model. Transmission profiles and ablation depths are compared with experimental results and similar trends are found. Our calculations reveal an interesting self-inhibiting mechanism: volumetric mass removal in the supercritical region triggers plasma shielding and therefore stops proceeding. This self-limiting process indicates that volumetric mass removal does not necessarily result in large ablation depths.

  5. Two-dimensional DNAPL migration affected by groundwater flow in unconfined aquifer.

    PubMed

    Kamon, Masashi; Endo, Kazuto; Kawabata, Junichi; Inui, Toru; Katsumi, Takeshi

    2004-07-05

    The dense non-aqueous phase liquid (DNAPL) migration process was experimentally investigated in a laboratory-scale tank (150 cm width, 82.5 cm height, and 15 cm depth) to assess a site characterization on DNAPL contamination below a groundwater table. The heterogeneous ground of the tank model consisted of Toyoura sand (hydraulic conductivity, k = 1.5 x 10(-2) cm/s for void ratio, e = 0.62) and silica #7 sand (k = 2.3 x 10(-3) cm/s for e = 0.72). A series of experiments was carried out with or without lateral groundwater flow. Hydrofluoroether was used as a representative DNAPL. The main results obtained in this study are as follows: (1) the DNAPL plume does not invade into the less permeable soil layer with higher displacement pressure head; (2) the DNAPL plume migrates faster with lateral groundwater flow than without it; (3) lateral groundwater flow does not affect lateral DNAPL migration; rather, it promotes downward migration; and (4) pore DNAPL pressure without groundwater flow is higher than that with it. The above experimental results were compared with numerical analysis. The fundamental behaviors of DNAPL source migration observed experimentally are expected to be useful for assessing the characteristics of two-dimensional DNAPL migration in an aquifer.

  6. BENCH-SCALE VISUALIZATION OF DNAPL REMEDIATION PROCESSES IN ANALOG HETEROGENEOUS AQUIFERS: SURFACTANT FLOODS, AND IN SITU OXIDATION USING PERMANGANATE

    EPA Science Inventory

    We have conducted well-controlled DNAPL remediation experiments using surfactants (Aerosol MA and Tween 80) to increase solubility and an oxidant (permanganate) to chemically degrade the DNAPL. Photographs and digital image analysis illustrate previously unobserved interactions b...

  7. Biodegradation of Chlorinated Solvents: Reactions near DNAPL and Enzyme Function

    SciTech Connect

    McCarty, P. L.; Spormann, Alfred M.; Criddle, Craig, S.

    2003-12-11

    Chlorinated solvents are among the most widespread groundwater contaminants in the country, contamination which is also among the most difficult and expensive for remediation. These solvents are biodegradable in the absence of oxygen, but this biodegradation requires both a food source for the organisms (electron donor) and the presence of chlorinated solvent biodegrading organisms. These two requirements are present naturally at some contamination sites, leading to natural attenuation of the solvents. If one or both requirements are absent, then engineered bioremediation either through addition of an external electron donor or through bioaugmentation with appropriate microorganisms, or both, may be used for site remediation. The most difficult case for cleanup is when a large residual of undissolved chlorinated solvents are present, residing as dense -non-aqueous-phase- liquid ( DNAPL). A major focus of this study was on the potential for biodegradation of the solvents when pre sent as DNAPL where concentrations are very high and potential for toxicity to microorganisms exist. Another focus was on a better understanding of the biological mechanisms involved in chlorinated solvent biodegradation . These studies were directed towards the chlorinated solvents, trichloroethene (TCE), tetrachloroethene or perchloroethene (PCE), and carbon tetrachloride (CT). The potential for biodegradation of TCE and PCE DNAPL was clearly demonstrated in this research. From column soil studies and batch studies we found there to be a clear advantage in focusing efforts at bioremediation near the DNAPL. Here, chlorinated solvent concentrations are the highest, both because of more favorable reaction kinetics and because such high solvent concentrations are toxic to microorganisms, such as methanogens, which compete with dehalogenators for the electron donor. Additionally, biodegradation near a PCE DNAPL results in an enhanced dissolution rate for the chlorinated solvent, by factors of

  8. Dissolution, Cyclodextrin-Enhanced Solubilization, and Mass Removal of an Ideal Multicomponent Organic Liquid

    PubMed Central

    Carroll, Kenneth C.; Brusseau, Mark L.

    2010-01-01

    Laboratory experiments and mathematical modeling were conducted to examine the influence of a hydroxypropyl-beta-cyclodextrin (HPCD) solution on the dissolution of single- and three-component organic liquids. The results of batch experiments showed that HPCD-enhanced solubilization of the organic-liquid mixtures was ideal (describable using Raoult’s Law), and that solubilization-enhancement factors were independent of mixture composition. Addition of the HPCD solution to columns containing residual saturations of the organic liquid enhanced the dissolution and removal of all three compounds in the mixture. The results of the column experiments and multicomponent rate-limited dissolution modeling suggest that solubilization was ideal for both water and cyclodextrin flushing. Concomitantly, the mass-flux reduction versus mass removal behavior was ideal for all experiments. Mass transfer was increased for HPCD solubilization relative to the water flushing due to solubility and concentration-gradient enhancement. Organic-liquid composition did not significantly impact mass transfer coefficients, and fractional mass removal behavior during HPCD solubilization was nearly identical for each compound whether present as a single component or in a mixture. Additionally, mass transfer coefficients for aqueous and HPCD solubilization for single and multicomponent mixtures were not statistically different upon normalizing by the solubility enhancement factor. PMID:19233508

  9. Nitrate Removal in Two Relict Oxbow Urban Wetlands: A 15N Mass-balance Approach

    EPA Science Inventory

    A 15N-tracer method was used to quantify nitrogen (N) removal processes in two relict oxbow wetlands located adjacent to the Minebank Run restored stream reach in Baltimore County (Maryland, USA) during summer 2009 and early spring 2010. A mass-balance approach was used to determ...

  10. Nitrate Removal in Two Relict Oxbow Urban Wetlands: A 15N Mass-balance Approach

    EPA Science Inventory

    A 15N-tracer method was used to quantify nitrogen (N) removal processes in two relict oxbow wetlands located adjacent to the Minebank Run restored stream reach in Baltimore County (Maryland, USA) during summer 2009 and early spring 2010. A mass-balance approach was used to determ...

  11. Summary and Status of DNAPL Characterization and Remediation Activities in the A/M-Area, Savannah River Site

    SciTech Connect

    Vangelas, K.M.

    2001-03-02

    This report summarizes historical A/M-Area DNAPL activities and data, and presents the overall A/M-Area strategy flowchart, the status work for each DNAPL source zone (or potential source zone), and future A/M-Area DNAPL plans.

  12. Factors Controlling DNAPL Migration in a Fracture Network: Experiments and Simulations

    NASA Astrophysics Data System (ADS)

    Ji, S.; Yeo, I.; Lee, K.

    2002-12-01

    Groundwater contamination by dense nonaqueous phase liquids (DNAPLs) has received considerable attention in recent years, and the attention on characterizing and quantifying the migration of DNAPL in geological formations has been given to the migration of DNAPL in porous media, not much in fractured rock. The spilled DNAPL that is heavier than water migrates downward to fractured bedrocks under the influence of gravity and is a long-term contaminant source. Although the progress has been accomplished on the development of algorithms for the numerical solution of the macroscopic models of contaminant transport in rock fractures, a lack of fundamental understanding exists concerning the interactive effects of the structural characteristics of fractures and fluid rheology on the patterns of DNAPL migration in a fracture network. In particular, little experimental work has been done on DNAPL migration in a fracture network. The two-dimensional fracture network was built up. Water was applied to both sides of a fracture network to have intended hydraulic head, and TCE was injected into one of vertical fractures. TCE migration process was recorded with digital camcorder. The dynamic macro-modified invasion percolation (DMMIP) model is suggested by integrating groundwater flow factor with MMIP that reflects the capillary effect, gravity-destabilization condition and viscous force of DNAPL. The information gained from experiments was analyzed and used for testing the DMMIP model to characterize the DNAPL migration pathway in a fracture network. DMMIP simulations and laboratory experiments show a good agreement. The results of DMMIP simulations and laboratory experiments show that in addition to gravity force, water viscous force considerably affects migration of DNAPL in rock fractures. This study will provide a step-stone for further developing reliable numerical simulators of the DNAPL migration in a fracture network that are required for the implementation of rational

  13. Chronocoulometry for quantitative control of mass removal in micro-structures and sensors

    NASA Astrophysics Data System (ADS)

    Nowakowski, B. K.; Smith, S. T.; Pratt, J. R.; Shaw, G. A.

    2012-10-01

    In this work, tungsten wires have been etched in a KOH electrolyte solution. Based on the oxidation state of the electrolytic dissolution reaction's product and time integration of the Faradaic current produced during the reaction, this method is capable of providing a direct measurement of the change in mass of a structure from anodic dissolution. To assess the application of this process for controlled mass removal spanning sub-micrograms to milligrams, two experimental studies and accompanying uncertainty analyses have been undertaken. In the first of these, 5 tungsten wires of length 30 mm were used to remove mass values ranging from 50 to 350 μg. Uncertainty estimates indicate relative combined standard uncertainties of less than 0.3% in the mass changes determined from the measurement of Faradaic current. Comparison of the mass change determined using the electrolytic method, and using a precision ultra-microbalance agreed within this uncertainty. The charge-based method was then applied to modify the dynamic characteristics of a quartz tuning fork oscillator. In these experiments, tungsten fiber attached to one tine of the oscillator was etched in 5 μg increments up to 120 μg of total removed mass. In general, frequency shifts of 2.8 Hz.μg-1 were observed, indicating sub-microgram resolution for the characterization of probes based on frequency shift and charge-based mass measurement. Taken together, this study provides the basis for a precision method for determining changes in mass based on electrical measurements from an electrochemical system. The utility of this technique is demonstrated through controlled modification of the dynamic properties of a mechanical oscillator.

  14. Chronocoulometry for quantitative control of mass removal in micro-structures and sensors

    SciTech Connect

    Nowakowski, B. K.; Smith, S. T.; Pratt, J. R.; Shaw, G. A.

    2012-10-15

    In this work, tungsten wires have been etched in a KOH electrolyte solution. Based on the oxidation state of the electrolytic dissolution reaction's product and time integration of the Faradaic current produced during the reaction, this method is capable of providing a direct measurement of the change in mass of a structure from anodic dissolution. To assess the application of this process for controlled mass removal spanning sub-micrograms to milligrams, two experimental studies and accompanying uncertainty analyses have been undertaken. In the first of these, 5 tungsten wires of length 30 mm were used to remove mass values ranging from 50 to 350 {mu}g. Uncertainty estimates indicate relative combined standard uncertainties of less than 0.3% in the mass changes determined from the measurement of Faradaic current. Comparison of the mass change determined using the electrolytic method, and using a precision ultra-microbalance agreed within this uncertainty. The charge-based method was then applied to modify the dynamic characteristics of a quartz tuning fork oscillator. In these experiments, tungsten fiber attached to one tine of the oscillator was etched in 5 {mu}g increments up to 120 {mu}g of total removed mass. In general, frequency shifts of 2.8 Hz{center_dot}{mu}g{sup -1} were observed, indicating sub-microgram resolution for the characterization of probes based on frequency shift and charge-based mass measurement. Taken together, this study provides the basis for a precision method for determining changes in mass based on electrical measurements from an electrochemical system. The utility of this technique is demonstrated through controlled modification of the dynamic properties of a mechanical oscillator.

  15. Field Demonstration of DNAPL Dehalogenation Using Emulsified Zero-Valent Iron

    NASA Technical Reports Server (NTRS)

    Quinn, Jacqueline; Geiger, Cherie; Clausen, Chris; Brooks, Kathleen; Coon, Christina; O'Hara, Suzanne; Krug, Thomas; Major, David; Yoon, Sam; Gavaskar, Arun; Holdsworth, Thomas

    2004-01-01

    This paper describes the results of the first field-scale demonstration conducted to evaluate the performance of nano-scale emulsified zero-valent iron (EZVI) injected into the saturated zone to enhance in situ dehalogenation of dense, non-aqueous phase liquids (DNAPLs) containing trichloroethene (TCE). EZVI is an innovative and emerging remediation technology. EZVI is a surfactant-stabilized, biodegradable emulsion that forms emulsion droplets consisting of an oil-liquid membrane surrounding zero-valent iron (ZVI) particles in water. EZVI was injected over a five day period into eight wells in a demonstration test area within a larger DNAPL source area at NASA's Launch Complex 34 (LC34) using a pressure pulse injection method. Soil and groundwater samples were collected before and after treatment and analyzed for volatile organic compounds (V005) to evaluate the changes in VOC mass, concentration and mass flux. Significant reductions in TCE soil concentrations (>80%) were observed at four of the six soil sampling locations within 90 days of EZVI injection. Somewhat lower reductions were observed at the other two soil sampling locations where visual observations suggest that most of the EZVI migrated up above the target treatment depth. Significant reductions in TCE groundwater concentrations (57 to 100%) were observed at all depths targeted with EZVI. Groundwater samples from the treatment area also showed significant increases in the concentrations of cis-1,2-dichloroethene (cDCE), vinyl chloride (VC) and ethene. The decrease in concentrations of TCE in soil and groundwater samples following treatment with EZVI is believed to be due to abiotic degradation associated with the ZVI as well as biodegradation enhanced by the presence of the oil and surfactant in the EZVI emulsion.

  16. Field demonstration of DNAPL dehalogenation using emulsified zero-valent iron

    NASA Technical Reports Server (NTRS)

    Quinn, Jacqueline; Geiger, Cherie; Clausen, Chris; Brooks, Kathleen; Coon, Christina; O'Hara, Suzanne; Krug, Thomas; Major, David; Yoon, Woong-Sang; Gavaskar, Arun; hide

    2005-01-01

    This paper describes the results of the first field-scale demonstration conducted to evaluate the performance of nanoscale emulsified zero-valent iron (EZVI) injected into the saturated zone to enhance in situ dehalogenation of dense, nonaqueous phase liquids (DNAPLs) containing trichloroethene (TCE). EZVI is an innovative and emerging remediation technology. EZVI is a surfactant-stabilized, biodegradable emulsion that forms emulsion droplets consisting of an oil-liquid membrane surrounding zero-valent iron (ZVI) particles in water. EZVI was injected over a five day period into eight wells in a demonstration test area within a larger DNAPL source area at NASA's Launch Complex 34 (LC34) using a pressure pulse injection method. Soil and groundwater samples were collected before and after treatment and analyzed for volatile organic compounds (VOCs) to evaluate the changes in VOC mass, concentration and mass flux. Significant reductions in TCE soil concentrations (>80%) were observed at four of the six soil sampling locations within 90 days of EZVI injection. Somewhat lower reductions were observed at the other two soil sampling locations where visual observations suggest that most of the EZVI migrated up above the target treatment depth. Significant reductions in TCE groundwater concentrations (57 to 100%) were observed at all depths targeted with EZVI. Groundwater samples from the treatment area also showed significant increases in the concentrations of cis-1,2-dichloroethene (cDCE), vinyl chloride (VC) and ethene. The decrease in concentrations of TCE in soil and groundwater samples following treatment with EZVI is believed to be due to abiotic degradation associated with the ZVI as well as biodegradation enhanced by the presence of the oil and surfactant in the EZVI emulsion.

  17. Field demonstration of DNAPL dehalogenation using emulsified zero-valent iron

    NASA Technical Reports Server (NTRS)

    Quinn, Jacqueline; Geiger, Cherie; Clausen, Chris; Brooks, Kathleen; Coon, Christina; O'Hara, Suzanne; Krug, Thomas; Major, David; Yoon, Woong-Sang; Gavaskar, Arun; Holdsworth, Thomas

    2005-01-01

    This paper describes the results of the first field-scale demonstration conducted to evaluate the performance of nanoscale emulsified zero-valent iron (EZVI) injected into the saturated zone to enhance in situ dehalogenation of dense, nonaqueous phase liquids (DNAPLs) containing trichloroethene (TCE). EZVI is an innovative and emerging remediation technology. EZVI is a surfactant-stabilized, biodegradable emulsion that forms emulsion droplets consisting of an oil-liquid membrane surrounding zero-valent iron (ZVI) particles in water. EZVI was injected over a five day period into eight wells in a demonstration test area within a larger DNAPL source area at NASA's Launch Complex 34 (LC34) using a pressure pulse injection method. Soil and groundwater samples were collected before and after treatment and analyzed for volatile organic compounds (VOCs) to evaluate the changes in VOC mass, concentration and mass flux. Significant reductions in TCE soil concentrations (>80%) were observed at four of the six soil sampling locations within 90 days of EZVI injection. Somewhat lower reductions were observed at the other two soil sampling locations where visual observations suggest that most of the EZVI migrated up above the target treatment depth. Significant reductions in TCE groundwater concentrations (57 to 100%) were observed at all depths targeted with EZVI. Groundwater samples from the treatment area also showed significant increases in the concentrations of cis-1,2-dichloroethene (cDCE), vinyl chloride (VC) and ethene. The decrease in concentrations of TCE in soil and groundwater samples following treatment with EZVI is believed to be due to abiotic degradation associated with the ZVI as well as biodegradation enhanced by the presence of the oil and surfactant in the EZVI emulsion.

  18. Development and application of a screening model for evaluating bioenhanced dissolution in DNAPL source zones

    NASA Astrophysics Data System (ADS)

    Phelan, Thomas J.; Abriola, Linda M.; Gibson, Jenny L.; Smits, Kathleen M.; Christ, John A.

    2015-12-01

    In-situ bioremediation, a widely applied treatment technology for source zones contaminated with dense non-aqueous phase liquids (DNAPLs), has proven economical and reasonably efficient for long-term management of contaminated sites. Successful application of this remedial technology, however, requires an understanding of the complex interaction of transport, mass transfer, and biotransformation processes. The bioenhancement factor, which represents the ratio of DNAPL mass transfer under microbially active conditions to that which would occur under abiotic conditions, is commonly used to quantify the effectiveness of a particular bioremediation remedy. To date, little research has been directed towards the development and validation of methods to predict bioenhancement factors under conditions representative of real sites. This work extends an existing, first-order, bioenhancement factor expression to systems with zero-order and Monod kinetics, representative of many source-zone scenarios. The utility of this model for predicting the bioenhancement factor for previously published laboratory and field experiments is evaluated. This evaluation demonstrates the applicability of these simple bioenhancement factors for preliminary experimental design and analysis, and for assessment of dissolution enhancement in ganglia-contaminated source zones. For ease of application, a set of nomographs is presented that graphically depicts the dependence of bioenhancement factor on physicochemical properties. Application of these nomographs is illustrated using data from a well-documented field site. Results suggest that this approach can successfully capture field-scale, as well as column-scale, behavior. Sensitivity analyses reveal that bioenhanced dissolution will critically depend on in-situ biomass concentrations.

  19. Application of an Optimal Search Strategy for the DNAPL Source Identification to a Field Site in Nanjing, China

    NASA Astrophysics Data System (ADS)

    Longting, M.; Ye, S.; Wu, J.

    2014-12-01

    Identification and removing the DNAPL source in aquifer system is vital in rendering remediation successful and lowering the remediation time and cost. Our work is to apply an optimal search strategy introduced by Zoi and Pinder[1], with some modifications, to a field site in Nanjing City, China to define the strength, and location of DNAPL sources using the least samples. The overall strategy uses Monte Carlo stochastic groundwater flow and transport modeling, incorporates existing sampling data into the search strategy, and determines optimal sampling locations that are selected according to the reduction in overall uncertainty of the field and the proximity to the source locations. After a sample is taken, the plume is updated using a Kalman filter. The updated plume is then compared to the concentration fields that emanate from each individual potential source using fuzzy set technique. The comparison followed provides weights that reflect the degree of truth regarding the location of the source. The above steps are repeated until the optimal source characteristics are determined. Considering our site case, some specific modifications and work have been done as follows. K random fields are generated after fitting the measurement K data to the variogram model. The locations of potential sources that are given initial weights are targeted based on the field survey, with multiple potential source locations around the workshops and wastewater basin. Considering the short history (1999-2010) of manufacturing optical brightener PF at the site, and the existing sampling data, a preliminary source strength is then estimated, which will be optimized by simplex method or GA later. The whole algorithm then will guide us for optimal sampling and update as the investigation proceeds, until the weights finally stabilized. Reference [1] Dokou Zoi, and George F. Pinder. "Optimal search strategy for the definition of a DNAPL source." Journal of Hydrology 376.3 (2009): 542

  20. DNAPL Dissolution in Bedrock Fractures And Fracture Networks

    DTIC Science & Technology

    2011-06-01

    capillary pressure, wettability , interfacial tension and relative permeability (63). The advancing DNAPL front and intersecting fractures will be only be...UCRL-JC-149856- ABS . ER-1554 Final Report 130 (12) Rubin, H., K. Rathfelder, K., Abriola, L.M., Spiller, M., Köngeter, J. Using continuum... wettability and saturation on liquid-liquid interfacial area in porous media. Environ. Sci. Technol. 2002, 37, 584-591. (94) Morley, M.C., Yamamoto, H

  1. Rapid detergent removal from peptide samples with ethyl acetate for mass spectrometry analysis.

    PubMed

    Yeung, Yee-Guide; Stanley, E Richard

    2010-02-01

    Detergents are required for the extraction of hydrophobic proteins and for the maintenance of their solubility in solution. However, the presence of detergents in the peptide samples severely suppresses ionization in mass spectrometry (MS) analysis and decreases chromatographic resolution in LC-MS. Thus, detergents must be removed for sensitive detection of peptides by MS. This unit describes a rapid protocol in which ethyl acetate extraction is used to remove octylglucoside from protease digests without loss of peptides. This procedure can also be used to reduce interference by sodium dodecyl sulfate, Nonidet P-40, or Triton X-100 in peptide samples for MS analysis.

  2. THE MEASUREMENT AND USE OF CONTAMINANT FLUX AS AN ASSESSMENT TOOL FOR DNAPL REMEDIAL PERFORMANCE

    EPA Science Inventory

    Current remedial techniques are unable to completely eliminate all dense nonaqueous phase liquid (DNAPL) from source zone areas at most sites, and conflicting views on the benefits of partial DNAPL source zone remediation exist in the literature. A comparison of contaminant flux...

  3. MEASUREMENT AND USE OF CONTAMINANT FLUX AS AN ASSESSMENT TOOL FOR DNAPL REMEDIAL PERFORMANCE

    EPA Science Inventory

    Current remedial techniques are unable to completely eliminate all dense nonaqueous phase liquid (DNAPL) from source zone areas at most sites, and conflicting views on the benefits of partial DNAPL source zone remediation exist in the literature. A comparison of contaminant flux...

  4. Assessment and Delineation of DNAPL Source Zones at Hazardous Waste Sites

    EPA Science Inventory

    This document provides a framework to assess the presence of DNAPL in the subsurface and for delineating the spatial extent of a DNAPL source zone. Direct and indirect site investigation methods are discussed, as well as their applicability in unconsolidated deposits and fracture...

  5. DOES FIELD DATA SHOW DOWNWARD MOBILIZATION OF DNAPL DURING THERMAL REMEDIATION?

    EPA Science Inventory

    The question of will DNAPLs be mobilized downward during thermal remediation has been asked many times. Indeed, downward mobilization of DNAPLs during steam injection has been observed in the lab. The mechanism for this downward mobilization was the concentration of the contami...

  6. DOES FIELD DATA SHOW DOWNWARD MOBILIZATION OF DNAPL DURING THERMAL REMEDIATION? (ABSTRACT)

    EPA Science Inventory

    The question of will DNAPLs be mobilized downward during thermal remediation has been asked many times. Indeed, downward mobilization of DNAPLs during steam injection has been observed in the lab. The mechanism for this downward mobilization was the concentration of the contami...

  7. Organic Dye Effects on DNAPL Entry Pressure in Water Saturated Porous Media

    SciTech Connect

    Iversen, G.M.

    2001-10-02

    One of three diazo dyes with the same fundamental structure have been used in most studies of DNAPL behavior in porous media to stain the NAPL: Sudan III, Sudan IV, or Oil-Red-O. The dyes are generally implicitly assumed to not influence DNAPL behavior. That assumption was tested using simple entry pressure experiments.

  8. Assessment and Delineation of DNAPL Source Zones at Hazardous Waste Sites

    EPA Science Inventory

    This document provides a framework to assess the presence of DNAPL in the subsurface and for delineating the spatial extent of a DNAPL source zone. Direct and indirect site investigation methods are discussed, as well as their applicability in unconsolidated deposits and fracture...

  9. THE MEASUREMENT AND USE OF CONTAMINANT FLUX AS AN ASSESSMENT TOOL FOR DNAPL REMEDIAL PERFORMANCE

    EPA Science Inventory

    Current remedial techniques are unable to completely eliminate all dense nonaqueous phase liquid (DNAPL) from source zone areas at most sites, and conflicting views on the benefits of partial DNAPL source zone remediation exist in the literature. A comparison of contaminant flux...

  10. MEASUREMENT AND USE OF CONTAMINANT FLUX AS AN ASSESSMENT TOOL FOR DNAPL REMEDIAL PERFORMANCE

    EPA Science Inventory

    Current remedial techniques are unable to completely eliminate all dense nonaqueous phase liquid (DNAPL) from source zone areas at most sites, and conflicting views on the benefits of partial DNAPL source zone remediation exist in the literature. A comparison of contaminant flux...

  11. Fracture of fusion mass after hardware removal in patients with high sagittal imbalance.

    PubMed

    Sedney, Cara L; Daffner, Scott D; Stefanko, Jared J; Abdelfattah, Hesham; Emery, Sanford E; France, John C

    2016-04-01

    As spinal fusions become more common and more complex, so do the sequelae of these procedures, some of which remain poorly understood. The authors report on a series of patients who underwent removal of hardware after CT-proven solid fusion, confirmed by intraoperative findings. These patients later developed a spontaneous fracture of the fusion mass that was not associated with trauma. A series of such patients has not previously been described in the literature. An unfunded, retrospective review of the surgical logs of 3 fellowship-trained spine surgeons yielded 7 patients who suffered a fracture of a fusion mass after hardware removal. Adult patients from the West Virginia University Department of Orthopaedics who underwent hardware removal in the setting of adjacent-segment disease (ASD), and subsequently experienced fracture of the fusion mass through the uninstrumented segment, were studied. The medical records and radiological studies of these patients were examined for patient demographics and comorbidities, initial indication for surgery, total number of surgeries, timeline of fracture occurrence, risk factors for fracture, as well as sagittal imbalance. All 7 patients underwent hardware removal in conjunction with an extension of fusion for ASD. All had CT-proven solid fusion of their previously fused segments, which was confirmed intraoperatively. All patients had previously undergone multiple operations for a variety of indications, 4 patients were smokers, and 3 patients had osteoporosis. Spontaneous fracture of the fusion mass occurred in all patients and was not due to trauma. These fractures occurred 4 months to 4 years after hardware removal. All patients had significant sagittal imbalance of 13-15 cm. The fracture level was L-5 in 6 of the 7 patients, which was the first uninstrumented level caudal to the newly placed hardware in all 6 of these patients. Six patients underwent surgery due to this fracture. The authors present a case series of 7

  12. Nanoscale and Microscale Iron Emulsions for Treating DNAPL

    NASA Technical Reports Server (NTRS)

    Geiger, Cherie L.

    2002-01-01

    This study demonstrated the feasibility of using emulsified nanoscale and microscale iron particles to enhance dehalogenation of (Dense Non-Aqueous Phase Liquid) DNAPL free-phase. The emulsified system consisted of a surfactant-stabilized, biodegradable oil-in-water emulsion with nanoscale or microscale iron particles contained within the emulsion droplets. It was demonstrated that DNAPLs, such as trichloroethene (TCE), diffuse through the oil membrane of the emulsion particle whereupon they reach an aqueous interior and the surface of an iron particle where dehalogenation takes place. The hydrocarbon reaction by-products of the dehalogenation reaction, primarily ethene (no chlorinated products detected), diffuse out of the emulsion droplet. This study also demonstrated that an iron-emulsion system could be delivered in-situ to the DNAPL pool in a soil matrix by using a simulated push well technique. Iron emulsions degraded pure TCE at a rate comparable to the degradation of dissolved phase TCE by iron particles, while pure iron had a very low degradation rate for free-phase TCE. The iron-emulsion systems can be injected into a sand matrix where they become immobilized and are not moved by flowing water. It has been documented that surfactant micelles possess the ability to pull pooled TCE into emulsion droplets where degradation of TCE takes place.

  13. A simulation and decision analysis approach to locating DNAPL in subsurface sediments

    SciTech Connect

    Borchers, B.; Conrad, S.H.; Webb, E.K.

    1997-09-01

    This report presents a strategy for delineating the location of residual dense non-aqueous phase liquids (DNAPL) that combines probabilistic simulations of DNAPL spill location and volume, geologic texture constraining migration pathways, migration physics through percolation modeling, and a decision analysis model to pick optimal locations for sampling wells. The authors` strategy is an iterative process of simulating the residual DNAPL location, selecting new locations for data collection, gathering data, and then using the data to condition further simulations of DNAPL migration. As they iterate through this process, data worth analysis is used to determine an appropriate stopping point. The authors present the results from a preliminary version of their model, showing how the process was used to delineate hypothetical DNAPL spills.

  14. Estimation of representative elementary volume for DNAPL saturation and DNAPL-water interfacial areas in 2D heterogeneous porous media

    NASA Astrophysics Data System (ADS)

    Wu, Ming; Cheng, Zhou; Wu, Jianfeng; Wu, Jichun

    2017-06-01

    Representative elementary volume (REV) is important to determine properties of porous media and those involved in migration of contaminants especially dense nonaqueous phase liquids (DNAPLs) in subsurface environment. In this study, an experiment of long-term migration of the commonly used DNAPL, perchloroethylene (PCE), is performed in a two dimensional (2D) sandbox where several system variables including porosity, PCE saturation (Soil) and PCE-water interfacial area (AOW) are accurately quantified by light transmission techniques over the entire PCE migration process. Moreover, the REVs for these system variables are estimated by a criterion of relative gradient error (εgi) and results indicate that the frequency of minimum porosity-REV size closely follows a Gaussian distribution in the range of 2.0 mm and 8.0 mm. As experiment proceeds in PCE infiltration process, the frequency and cumulative frequency of both minimum Soil-REV and minimum AOW-REV sizes change their shapes from the irregular and random to the regular and smooth. When experiment comes into redistribution process, the cumulative frequency of minimum Soil-REV size reveals a linear positive correlation, while frequency of minimum AOW-REV size tends to a Gaussian distribution in the range of 2.0 mm-7.0 mm and appears a peak value in 13.0 mm-14.0 mm. Undoubtedly, this study will facilitate the quantification of REVs for materials and fluid properties in a rapid, handy and economical manner, which helps enhance our understanding of porous media and DNAPL properties at micro scale, as well as the accuracy of DNAPL contamination modeling at field-scale.

  15. Removal of chlorofluorocarbons by increased mass exchange between the stratosphere and troposphere in a changing climate.

    PubMed

    Butchart, N; Scaife, A A

    2001-04-12

    Chlorofluorocarbons (CFCs), along with bromine compounds, have been unequivocally identified as being responsible for most of the anthropogenic destruction of stratospheric ozone. With curbs on emissions of these substances, the recovery of the ozone layer will depend on their removal from the atmosphere. As CFCs have no significant tropospheric removal process, but are rapidly photolysed above the lower stratosphere, the timescale for their removal is set mainly by the rate at which air is transported from the troposphere into the stratosphere. Using a global climate model we predict that, in response to the projected changes in greenhouse-gas concentrations during the first half of the twenty-first century, this rate of mass exchange will increase by 3% per decade. This increase is due to more vigorous extra-tropical planetary waves emanating from the troposphere. We estimate that this increase in mass exchange will accelerate the removal of CFCs to an extent that recovery to levels currently predicted for 2050 and 2080 will occur 5 and 10 years earlier, respectively.

  16. Removal of easily biodegradable organic compounds by drinking water biofilms: analysis of kinetics and mass transfer.

    PubMed

    Gagnon, G A; Huck, P M

    2001-07-01

    This paper evaluates the rate of utilization of easily biodegradable organic compounds by drinking water biofilms. Tap water, which had been filtered through biologically active granular activated carbon, was used as an innoculum for biofilm growth in annular reactors (ARs). Synthetic cocktails of easily biodegradable material in the concentration range of 50-2,000 mgC/m3 were used as substrate for biofilm growth. Influent and effluent aggregate concentrations of biodegradable organic matter (BOM) were calculated by adding the measurable BOM components on a mass carbon basis. The aggregate BOM values were used for calculating the observed Damköhler number and Theile modulus (based on a reaction rate per unit surface area), which were used to determine whether external or internal mass transfer limited BOM removal. For all of the experimental trials, it was shown that neither external nor internal mass transfer limited BOM removal. Because the biofilms in this research are thin and the fact that mass transfer is not limiting, it was assumed that the bulk BOM concentration was approximately equal to the average BOM concentration in the biofilm. A linear model was obtained for the aggregate BOM flux and the product of the effluent BOM concentration and the biofilm density. The slope or the areal biodegradation rate (ka) for the aggregate BOM was 0.033 m/h, as determined through a linear regression.

  17. Fluid and porous media property effects on dense nonaqueous phase liquid migration and contaminant mass flux.

    PubMed

    Totten, C T; Annable, M D; Jawitz, J W; Delfinot, J J

    2007-03-01

    The effects of fluid and porous media properties on dense nonaqueous phase liquid (DNAPL) migration and associated contaminant mass flux generation were evaluated. Relationships between DNAPL mass and solute mass flux were generated by measuring steady-state mass flux following stepwise injection of perchloroethylene (PCE) into flow chambers packed with homogeneous porous media. The effects of fluid properties including density and interfacial tension (IFT), and media properties including grain size and wettability were evaluated by varying the density contrast and interfacial tension properties between PCE and water, and by varying the porous media mean grain diameter and wettability characteristics. Contaminant mass flux was found to increase as grain size decreased, suggesting enhanced lateral and vertical DNAPL spreading with higher fluid entry pressure. Mass flux showed a slight increase as the DNAPL approached neutral buoyancy, likely due to enhanced vertical spreading above the injection point. DNAPL spatial distribution and contaminant mass flux were only minimally affected by IFT and by intermediate-level wettability changes, but were dramatically affected by wettability reversal. The relationship between DNAPL loading and flux generation became more linear as grain size decreased and density contrast between fluids decreased. These results imply that capillary flow characteristics of the porous media and fluid properties will control mass flux generation from source zones.

  18. Kinetics and the mass transfer mechanism of hydrogen sulfide removal by biochar derived from rice hull.

    PubMed

    Shang, Guofeng; Liu, Liang; Chen, Ping; Shen, Guoqing; Li, Qiwu

    2016-05-01

    The biochar derived from rice hull was evaluated for its abilities to remove hydrogen sulfide (H2S) from gas phase. The surface area and pH of the biochar were compared. The biochar derived from rice hull was evaluated for its abilities to remove hydrogen sulfide (H2S) from gas phase. The surface area and pH of the biochar were compared. The different pyrolysis temperature has great influence on the adsorption of H2S. At the different pyrolysis temperature, the H2S removal efficiency of rice hull-derived biochar was different. The adsorption capacities of biochar were 2.09 mg·g(-1), 2.65 mg·g(-1), 16.30 mg·g(-1), 20.80 mg·g(-1), and 382.70 mg·g(-1), which their pyrolysis temperatures were 100 °C, 200 °C, 300 °C, 400 °C and 500 °C respectively. Based on the Yoon-Nelson model, it analyzed the mass transfer mechanism of hydrogen sulfide adsorption by biochar. The paper focuses on the biochar derived from rice hull-removed hydrogen sulfide (H2S) from gas phase. The surface area and pH of the biochar were compared. The different pyrolysis temperatures have great influence on the adsorption of H2S. At the different pyrolysis temperatures, the H2S removal efficiency of rice hull-derived biohar was different. The adsorption capacities of biochar were 2.09, 2.65, 16.30, 20.80, and 382.70 mg·g(-1), and their pyrolysis temperatures were 100, 200, 300, 400, and 500 °C, respectively. Based on the Yoon-Nelson model, the mass transfer mechanism of hydrogen sulfide adsorption by biochar was analyzed.

  19. IN-SITU CHEMICAL OXIDATION - DNAPL MASS REDUCTION TECHNOLOGY

    EPA Science Inventory

    In-situ chemical oxidation (ISCO) is a rapidly developing technology used at hazardous waste sites where oxidants and complimentary reagents are injected into the subsurface to transform organic contaminants into less toxic byproducts. This technology is being used at new sites ...

  20. Mass removal by oxidation and sublimation of porous graphite during fiber laser irradiation

    NASA Astrophysics Data System (ADS)

    Phillips, Grady T.; Bauer, William A.; Fox, Charles D.; Gonzales, Ashley E.; Herr, Nicholas C.; Gosse, Ryan C.; Perram, Glen P.

    2017-01-01

    The various effects of laser heating of carbon materials are key to assessing laser weapon effectiveness. Porous graphite plates, cylinders, and cones with densities of 1.55 to 1.82 g/cm3 were irradiated by a 10-kW fiber laser at 0.075 to 3.525 kW/cm2 for 120 s to study mass removal and crater formation. Surface temperatures reached steady state values as high as 3767 K. The total decrease in sample mass ranged from 0.06 to 6.29 g, with crater volumes of 0.52 to 838 mm3, and penetration times for 12.7-mm-thick plates as short as 38 s. Minor contaminants in the graphite samples produced calcium and iron oxide to be redeposited on the graphite surface. Dramatic graphite crystalline structures are also produced at higher laser irradiances. Significantly increased porosity of the sample is observed even outside the laser-irradiated region. Total mass removed increases with deposited laser energy at a rate of 4.83 g/MJ for medium extruded graphite with an apparent threshold of 0.15 MJ. At ˜3.5 kW/cm2, the fractions of the mass removed from the cylindrical samples in the crater, surrounding trench, and outer region of decreased porosity are 38%, 47%, and 15%, respectively. Graphite is particularly resistant to damage by high power lasers. The new understanding of graphite combustion and sublimation during laser irradiation is vital to the more complex behavior of carbon composites.

  1. Time scales of DNAPL migration in sandy aquifers examined via numerical simulation

    SciTech Connect

    Gerhard, J.I.; Pang, T.; Kueper, B.H.

    2007-03-15

    The time required for dense nonaqueous phase liquid (DNAPL) to cease migrating following release to the subsurface is a valuable component of a site conceptual model. This study uses numerical simulation to investigate the migration of six different DNAPLs in sandy aquifers. The most influential parameters governing migration cessation time are the density and viscosity of the DNAPL and the mean hydraulic conductivity of the aquifer. Releases of between 1 and 40 drums of chlorinated solvent DNAPLs, characterized by relatively high density and low viscosity, require on the order of months to a few years to cease migrating in a heterogeneous medium sand aquifer having an average hydraulic conductivity of 7.4 x 10{sup -3} cm/s. In contrast to this, the release of 20 drums of coal tar {rho}{sub D} = 1061 kg/m{sup 3}, {mu}{sub D} = 0.161 Pa(.)s) requires more than 100 years to cease migrating in the same aquifer. Altering the mean hydraulic conductivity of the aquifer results in a proportional change in cessation times. Parameters that exhibit relatively little influence on migration time scales are the DNAPL-water interfacial tension, release volume, source capillary pressure, mean aquifer porosity, and ambient ground water hydraulic gradient. This study also demonstrates that low-density DNAPLs (e.g., coal tar) give rise to greater amounts of lateral spreading and greater amounts of pooling on capillary barriers than high-density DNAPLs such as trichloroethylene or tetrachloroethylene.

  2. Selenium removal and mass balance in a constructed flow-through wetland system.

    PubMed

    Gao, S; Tanji, K K; Lin, Z Q; Terry, N; Peters, D W

    2003-01-01

    A field study on the removal of Se from agricultural subsurface drainage was conducted from May 1997 to February 2001 in the Tulare Lake Drainage District (TLDD) of San Joaquin Valley, California. A flow-through wetland system was constructed consisting of ten 15- x 76-m unlined cells that were continuously flooded and planted with either a monotype or combination of plants, including sturdy bulrush [Schoenoplectus robustus (Pursh) M.T. Strong], baltic rush (Juncus balticus Willd.), smooth cordgrass (Spartina alterniflora Loisel.), rabbitsfoot grass [Polypogon monspeliensis (L.) Desf.], salt-grass lDistichlis spicata (L.) Greene], cattail (Typha latifolia L.), tule [Schoenoplectus acutus (Muhl. ex Bigelow) A. Löve & D. Löve], and widgeon grass (Ruppia maritima L.). One cell had no vegetation planted. The objectives of this research were to evaluate Se removal efficiency of each wetland cell and to carry out a mass balance on Se. The inflow drainage water to the cells had average annual Se concentrations of 19 to 22 microg L(-1) dominated by selenate [Se(VI), 95%]. Average weekly water residence time varied from about 3 to 15 d for Cells 1 through 7 (target 7 d), 19 to 33 d for Cells 8 and 9 (target 21 d), and 13 to 18 d for Cell 10 (target 14 d). Average weekly Se concentration ratios of outflow to inflow ranged from 0.45 to 0.79 and mass ratio (concentration x water volume) from 0.24 to 0.52 for year 2000, that is, 21 to 55% reduction in Se concentration and 48 to 76% Se removal in mass by the wetland, respectively. The nonvegetated cell showed the least Se removal both in concentration and in mass. The global mass balance showed that on the average about 59% of the total inflow Se was retained within the cells and Se outputs were outflow (35%), seepage (4%), and volatilization (2%). Independent measurements of the Se retained in the cells totaled 53% of the total Se inflow: 33% in the surface (0-20 cm) sediment, 18% in the organic detrital layer above the

  3. Effects of Gravity and Aperture Statistics on DNAPL Entrapment in Fractures

    NASA Astrophysics Data System (ADS)

    Beattie, J. A.; Cianflone, S.; Dickson, S. E.

    2014-12-01

    Dense non-aqueous phase liquids (DNAPLs) are an important class of groundwater contaminants. Their migration pathways are particularly difficult to locate in fractured rock aquifers, which are abundant in North America. Over one million people in Southern Ontario alone obtain their drinking water from the Silurian dolostone bedrock. Once a DNAPL is trapped in an aquifer, it becomes a long-term threat to the source water quality. It is imperative to be able to locate and quantify trapped DNAPL to implement appropriate remedial strategies. This study quantifies volumetric DNAPL entrapment utilizing an invasion percolation (IP) approach to simulate the imbibition of water in a DNAPL-saturated fracture. The relationship between the volumetric fraction of trapped DNAPL, aperture field statistics and fracture orientation was investigated by varying a number of parameters; overall, 34,560 simulation were completed. The standard deviation (σb) and mean (μb) of the apertures were varied from 0.01-0.3 mm and 0.5-1.5 mm, respectively. The standard deviation (σz) and correlation length (λz) of the mid aperture field were varied from 0.01-10mm and 5-50mm, respectively. Fracture orientation was varied from 60o above (super-horizontal) to 60o below (sub-horizontal) horizontal.The results demonstrate that: 1) fractures oriented sub-horizontally permit the complete drainage of DNAPL, though this does not occur for horizontal and super-horizontal fractures; 2) when the coefficient of variation (COV) is larger than 0.1 the fracture orientation has little effect on the volumetric ratio of DNAPL entrapped; and 3) increasing standard deviation of the mid aperture field increases the range of the volumetric ratio of trapped DNAPL.

  4. Removal of nonthyroidal neck masses with improved cosmetic outcomes in skin-lifting surgery.

    PubMed

    Roh, Jong-Lyel; Yoon, Yeo-Hoon; Park, Chan Il

    2006-09-01

    To evaluate the cosmetic benefit of neck skin-lifting surgery for the removal of nonthyroidal neck masses. Fifty patients with neck masses were divided into the following 2 surgical groups that were matched in age, sex, and the size, location, and pathology of lesions: skin lifting (n = 25) and conventional (n = 25). The operation time, hospital stay, complications, and subjective satisfaction with the incision scar as assessed on a visual analogue scale (VAS) were compared between the 2 groups. All but 2 lesions (lymphomas) were benign and were removed completely, drained, or biopsied. The surgery time, hospital stay, and complication rates did not differ significantly between the groups. The mean satisfaction score of the patients was 8.2 +/- 1.1 in the skin-lifting surgery group and 4.8 +/- 2.5 in the controls (P < 0.001). The incision scars were commonly hidden by natural hair or collars in the patients who received skin-lifting surgery. This surgical technique can be safely applied to most benign masses in the entire neck excluding the thyroid region, especially in patients who prefer neck scars to be invisible. B-2b.

  5. Transport, Targeting, and Applications of Metallic Functional Nanoparticles for Degradation of DNAPL Chlorinated Organic Solvents

    SciTech Connect

    Gregory V. Lowry; Sara Majetich; Krzysztof Matyjaszewski; David Sholl; Robert Tilton

    2006-12-27

    Dense Non-Aqueous Phase Liquid (DNAPL) such as trichloroethylene act as long term sources of groundwater contaminants and are difficult and expensive to remediate. DNAPL-contaminated sites are a significant financial liability for the Department of Energy and the private sector. The objective of this study was to engineer reactive Fe-based nanoparticles with specialized polymeric coatings to make them mobile in the subsurface and to provide them with an affinity for the DNAPL/water interface. The synthesis, characterization, and reactivity/mobility of the engineered particles, and a molecular dynamic model that predicts their behavior at the DNPAL/water interface are described in this report.

  6. Mechanisms of material removal and mass transport in focused ion beam nanopore formation

    SciTech Connect

    Das, Kallol Johnson, Harley T.; Freund, Jonathan B.

    2015-02-28

    Despite the widespread use of focused ion beam (FIB) processing as a material removal method for applications ranging from electron microscope sample preparation to nanopore processing for DNA sequencing, the basic material removal mechanisms of FIB processing are not well understood. We present the first complete atomistic simulation of high-flux FIB using large-scale parallel molecular dynamics (MD) simulations of nanopore fabrication in freestanding thin films. We focus on the root mechanisms of material removal and rearrangement and describe the role of explosive boiling in forming nanopores. FIB nanopore fabrication is typically understood to occur via sputter erosion. This can be shown to be the case in low flux systems, where individual ion impacts are sufficiently separated in time that they may be considered as independent events. But our detailed MD simulations show that in high flux FIB processing, above a threshold level at which thermal effects become significant, the primary mechanism of material removal changes to a significantly accelerated, thermally dominated process. Under these conditions, the target is heated by the ion beam faster than heat is conducted away by the material, leading quickly to melting, and then continued heating to nearly the material critical temperature. This leads to explosive boiling of the target material with spontaneous bubble formation and coalescence. Mass is rapidly rearranged at the atomistic scale, and material removal occurs orders of magnitude faster than would occur by simple sputtering. While the phenomenology is demonstrated computationally in silicon, it can be expected to occur at lower beam fluxes in other cases where thermal conduction is suppressed due to material properties, geometry, or ambient thermal conditions.

  7. Use of an Intermediate-Scale Tank to Study Strategies for Modified NZVI Emplacement for Effective Treatment of DNAPL Source Zones

    NASA Astrophysics Data System (ADS)

    Illangasekare, T. H.; Mittal, M.; Phenrat, T.; Fagerlund, F.; Kim, H.; Cihan, A.; Lowry, G. V.

    2009-12-01

    Dense non-aqueous phase liquid (DNAPL) sources act as long term sources of ground water contamination. Emplacing modified nano-scale zero valent iron (NZVI) particles in the source zone and area immediately downstream of the source zone may serve the dual purpose of reducing the mass transfer from entrapped DNAPL and reductive dechlorination of the dissolved mass, thus reducing the total mass loading to the plume. Placement of NZVI is expected to alter porosity resulting in flow bypassing which may reduce treatment efficiency. The magnitude of this reduction will depend on the NZVI mass emplacement and its distribution. Another issue of concern is whether DNAPL mass rebounds if the emplaced NZVI is oxidized. In an ongoing study, the basic processes of NZVI reactivity and mass flux reduction were investigated in small cells, columns and tanks. To understand these processes and upscale them to larger systems, a series of experiments were conducted in a two-dimensional intermediate scale tank. This paper presents the results from one of these experiments that focused on evaluating the effects of emplacing the modified NZVI particles in the source zone with the DNAPL and to intercept the dissolved plume immediately down gradient of the source with the goal of evaluating and quantifying the net mass flux loading to the plume. A 5 cm x 5 cm PCE source zone in a coarse sand lens embedded in a finer sand matrix was created in an intermediate scale tank 2.4 m x 1.2 m x 0.55 m. The mass flux generation from source zone and the plume configuration were monitored using aqueous samples extracted at 4 vertical arrays containing 9 ports in each. Polymer coated NZVI particles were injected 7.5 cm downstream of the source zone creating a reactive zone of 14 cm x 14 cm x 5.5 cm such that the particles blanketed the PCE source zone. Dissolved PCE concentrations were monitored after NZVI injection using the same vertical sampling array. Dechlorination byproducts were monitored to

  8. Screening commercial surfactants suitable for remediating DNAPL source zones by solubilization

    SciTech Connect

    Zhou, M.; Rhue, R.D.

    2000-05-15

    Surfactants can enhance the removal of nonaqueous-phase-liquids (NAPLs) from porous media by two very different mechanisms: (1) increased solubilization that occurs in the presence of surfactant micelles and (2) mobilization of NAPL ganglia held by capillary forces. Solubilization technologies pose less risk of uncontrolled NAPL migration and are less complex to design. Since dense-NAPLs, like PCE, pose the greatest risk of migration, there is a need for more information on surfactants that are capable of solubilizing DNAPLs and removing them as water continuous, low viscosity, microemulsion without mobilization. Forty-two commercial, water-soluble surfactants were screened for PCE solubilization in batch experiments and one nonionic (Brij 97) and one anionic (SDS) surfactant were further evaluated in column experiments. Of the 42 surfactants that were screened, 12 nonionic surfactants with HLB values between 10.8 and 13.2 solubilized the most PCE. However, as PCE solubilization exceeded {approximately}40,000 mg/L, macroemulsion stability became a problem. Addition of IPA did not affect the amount of PCE solubilized but decreased macroemulsion stability, resulting in more rapid formation of Winsor Type 1 microemulsions. The most efficient surfactants were Brij 97 and Ritoleth 10, both being ethoxylated oleyl alcohol ethers, At 3 wt % IPA and surfactant, these surfactants solubilized >70,000 mg PCE/L. In column experiments, Brij 97/IPA removed >92% of the residual PCE in 11 pore volumes without mobilizing the PCE. An SDS/pentanol/IPA system removed 98% in {approximately}9.5 pore volumes, but about 30% of the PCE was mobilized. Removal of PCE was rate-limited with Brij 97/IPA, suggesting that flow interruption may be an effective remediation strategy.

  9. Mass-transfer limitations for nitrate removal in a uranium-contaminated aquifer.

    PubMed

    Luo, Jian; Cirpka, Olaf A; Wu, Weimin; Fienen, Michael N; Jardine, Philip M; Mehlhorn, Tonia L; Watson, David B; Criddle, Craig S; Kitanidis, Peter K

    2005-11-01

    A field test on in situ subsurface bioremediation of uranium(VI) is underway at the Y-12 National Security Complex in the Oak Ridge Reservation, Oak Ridge, TN. Nitrate has a high concentration at the site, which prevents U(VI) reduction, and thus must be removed. An acidic-flush strategy for nitrate removal was proposed to create a treatment zone with low levels of accessible nitrate. The subsurface at the site contains highly interconnected fractures surrounded by matrix blocks of low permeability and high porosity and is therefore subject to preferential flow and matrix diffusion. To identify the heterogeneous mass transfer properties, we performed a novel forced-gradient tracer test, which involved the addition of bromide, the displacement of nitrate, and the rebound of nitrate after completion of pumping. The simplest conceptualization consistent with the data is that the pore-space consists of a single mobile domain, as well as a fast and a slowly reacting immobile domain. The slowly reacting immobile domain (shale matrix) constitutes over 80% of the pore volume and acts as a long-term reservoir of nitrate. According to simulations, the nitrate stored in the slowly interacting immobile domain in the fast flow layer, at depths of about 12.2-13.7 m, will be reduced by an order of magnitude over a period of about a year. By contrast, the mobile domain rapidly responds to flushing, and a low average nitrate concentration can be maintained if the nitrate is removed as soon as it enters the mobile domain. A field-scale experiment in which the aquifer was flushed with acidic solution confirmed our understanding of the system. For the ongoing experiments on microbial U(VI) reduction, nitrate concentrations must be low in the mobile domain to ensure U(VI) reducing conditions. We therefore conclude that the nitrate leaching out of the immobile pore space must continuously be removed by in situ denitrification to maintain favorable conditions.

  10. Final Laboratory Treatability Report for: Emulsified Zero Valent Iron Treatment of Chlorinated Solvent DNAPL Source Areas (Rev 1)

    DTIC Science & Technology

    2006-01-23

    transport of dissolved chlorinated solvents to the PRB for treatment, and therefore PRBs do not reduce the clean - up time for sites where DNAPL is...containing ZVI are quickly surrounded by a passivating layer – such as a shell of oxide which limits the ZVI corrosion rate (Nurmi, et al. 2005...fast-reacting nZVI may however enhance the dissolution of the DNAPL and reduce the clean up time for source zone DNAPL (Seagren et al. 1994

  11. On the Importance of Gravity in DNAPL Invasion of Saturated Horizontal Fractures.

    PubMed

    Cianflone, Sean P L; Dickson, Sarah E; Mumford, Kevin G

    2017-01-01

    Invasion percolation (IP) models of dense non-aqueous phase liquid (DNAPL) invasion into saturated horizontal fractures typically neglect viscous and gravity forces, as it is assumed that capillarity dominates in many situations. An IP model simulating DNAPL invasion into saturated horizontal fractures was modified to include gravity as a local effect. The model was optimized using a genetic algorithm, and demonstrated that the inclusion of gravity is important for replicating the architecture of the DNAPL invasion pattern. The optimized gravity-included simulation showed the DNAPL invasion pattern to be significantly more representative of the experimentally observed pattern (80% accuracy) than did the optimized gravity-neglected simulation (70% accuracy). Additional simulations of DNAPL invasion in 360 randomly generated fractures were compared with and without gravity forces. These simulations showed that with increasing fracture roughness, the minimum difference between simulations with and without gravity increases to 35% for a standard deviation of the mid-aperture elevation field (SDz ) of 10 mm. Even for low roughness (SDz = 0.1 mm), the difference was as high as 30%. Furthermore, a scaled Bond Number is defined which includes data regarding DNAPL type, media type and statistical characteristics of the fracture. The value of this scaled Bond Number can be used to determine the conditions under which gravity should be considered when simulating DNAPL invasion in a macroscopically horizontal fracture. Finally, a set of equations defining the minimum and maximum absolute percentage difference between gravity-included and gravity-neglected simulations is presented based on the fracture and DNAPL characteristics. © 2016, National Ground Water Association.

  12. Migration and Entrapment of DNAPLs in Heterogeneous Systems: Impact of Waste and Porous Medium Composition

    SciTech Connect

    Linda M. Abriola; Avery H. Demond

    2005-01-10

    Dense nonaqueous phase liquids (DNAPLs) pose a significant threat to soil and groundwater at Department of Energy (DOE) sites. Evidence suggests that subsurface wettability variations are present at many of these sites as a result of spatical and temporal variations in aqueous phase chemistry, contaminant aging, mineralogy and organic matter. The presence of such heterogeneity may significantly influence DNAPL migration and entrapment in the saturated zone.

  13. Metric Identification and Protocol Development for Characterizing DNAPL Source Zone Architecture and Associated Plume Response

    DTIC Science & Technology

    2013-09-01

    capillary pressure parameters, and the distribution of persistent low permeability layers were the most significant factors influencing DNAPL source...inside diameter; Agilent Technologies, Santa Barbara, CA) that was maintained at a constant pressure of 14.5 psi with helium as the carrier gas. In...vacuum pressure for a minimum of 12 hours to minimize the entrapment of air in the porous media. Multicomponent DNAPL solutions and surfactant

  14. Impact of Clay DNAPL Interactions on Transport and Storage of Chlorinated Solvents in Low Permeability Zones

    DTIC Science & Technology

    2015-02-01

    process , or service by trade name, trademark, manufacturer , or otherwise, does not necessarily constitute or imply its endorsement, recommendation...of dissolution being key. In particular, if DNAPL is present in the cracks, it is the process of DNAPL dissolution which drives the contaminant ...continuing diffusion of the contaminant farther into these zones, back diffusion is much slower and longer lasting than the diffusion process that originally

  15. Fundamental Study of the Delivery of Nanoiron to DNAPL Source Zones in Naturally Heterogeneous Field Systems

    DTIC Science & Technology

    2012-09-01

    physical and chemical principles controlling colloid transport (e.g. particle-particle interactions , fluid velocity, grain/pore size). Particle and...NZVI in DNAPL contaminated zones of a naturally heterogeneous subsurface where the free phase is entrapped in a complex architecture and 2) understand... interactions , fluid velocity, grain/pore size). Particle and environmental factors affecting NZVI reactivity and the ability to provide DNAPL

  16. Sensitivity analysis of autotrophic N removal by a granule based bioreactor: Influence of mass transfer versus microbial kinetics.

    PubMed

    Vangsgaard, Anna Katrine; Mauricio-Iglesias, Miguel; Gernaey, Krist V; Smets, Barth F; Sin, Gürkan

    2012-11-01

    A comprehensive and global sensitivity analysis was conducted under a range of operating conditions. The relative importance of mass transfer resistance versus kinetic parameters was studied and found to depend on the operating regime as follows: Operating under the optimal loading ratio of 1.90(gO(2)/m(3)/d)/(gN/m(3)/d), the system was influenced by mass transfer (10% impact on nitrogen removal) and performance was limited by AOB activity (75% impact on nitrogen removal), while operating above, AnAOB activity was limiting (68% impact on nitrogen removal). The negative effect of oxygen mass transfer had an impact of 15% on nitrogen removal. Summarizing such quantitative analyses led to formulation of an optimal operation window, which serves a valuable tool for diagnosis of performance problems and identification of optimal solutions in nitritation/anammox applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Interpreting DNAPL saturations in a laboratory-scale injection with GPR data and direct core measurements

    USGS Publications Warehouse

    Johnson, Raymond H.; Poeter, Eileen P.

    2003-01-01

    Ground penetrating radar (GPR) is used to track a dense non-aqueous phase liquid (DNAPL) injection in a laboratory sand tank. Before data reduction, GPR data provide a qualitative measure of DNAPL saturation and movement. One-dimensional (1D) GPR modeling provides a quantitative interpretation of DNAPL volume within a given thickness during and after the injection. This is confirmed qualitatively by visual inspection of cores and two-dimensional GPR modeling. DNAPL saturation in sub-layers of that thickness could not be quantified because calibration of the 1D GPR model is non-unique when both permittivity and depth of multiple layers are unknown. Accurate quantitative interpretation of DNAPL volumes using 1D GPR modeling requires: 1) identification of a suitable target that produces a strong reflection and is not subject to any multidimensional interference; 2) knowledge of the exact depth of that target; and 3) use of two-way radar-wave travel times through the medium to the target to determine the permittivity of the intervening material, which eliminates reliance upon reflection amplitude. With geologic conditions that are suitable for GPR surveys (i.e., shallow depths and low electrical conductivities), the procedures in this laboratory study can be adapted to a field site to identify DNAPL source zones after a release has occurred.

  18. Delineation of creosote-based DNAPLs using CPT-deployed laser induced fluorescence

    SciTech Connect

    Ruggery, D.A. Jr.; Misquitta, N.J; Coll, F.R..

    1996-12-01

    This paper presents a case study of the first commercial use of cone penetrometer testing (CPT)/deployed laser induced fluorescence (LIF) to address the following objectives at a creosote DNAPL site. The objectives of the investigation using CPT/LIF were to: quickly and cost effectively delineate the horizontal and vertical extent of creosote DNAPL in soil/groundwater; delineate/differentiate creosote DNAPL constituents within the extent of DNAPL; delineate dissolved-phase versus free phase DNAPL compounds in the subsurface. The complexity of investigating the extent of creosote DNAPL magnifies the time and cost of the application of conventional investigative techniques. The application of CPT/LIF at the subject site allowed a comparison between CPT/LIF and more conventional investigative techniques. If the objectives were achieved in a shorter time-frame, and at a lesser cost than traditional methods, then the CPT/LIF method would be confirmed as a viable, field-scale technology for investigating appropriate wood-treating sites.

  19. Estimation of mass transfer and kinetics in operating biofilters for removal of VOCs

    SciTech Connect

    Barton, J.W.; Davison, B.H.; Gable, C.C.

    1997-11-18

    Long-term, stable operation of trickle-bed bioreactors remains desirable, but is difficult to achieve for industrial processes, which generate continuous streams of dilute gaseous hydrocarbons. Mass transfer and kinetic parameters are difficult to measure, complicating predictive estimates. Two methods are presented which were used to predict the importance of mass transfer versus kinetics limitations in operating trickle-bed biofilters. Both methods altered the overall kinetic activity of the biofilter and estimated the effective mass transfer coefficient (K{sub 1}a) by varying the VOC (volatile organic contaminant) loading rate and concentration. The first method, used with developing biofilters possessing low biomass, involved addition of cultured biomass to the recirculating liquid to effect an overall change in VOC removal capacity. The second method altered the total bed temperature of a well-established biofilter to effect a change. Results and modeling from these experiments are presented for a mixed culture biofilter which is capable of consuming sparingly soluble alkanes, such as pentane and isobutane. Methods to control overgrowth are discussed which were used to operate one reactor continuously for over 24 months with sustained degradation of VOC alkanes with a rate of 50 g/h/m{sup 3}.

  20. Numerical Modeling for Integrated Design of a DNAPL Partitioning Tracer Test

    NASA Astrophysics Data System (ADS)

    McCray, J. E.; Divine, C. E.; Dugan, P. J.; Wolf, L.; Boving, T.; Louth, M.; Brusseau, M. L.; Hayes, D.

    2002-12-01

    Partitioning tracer tests (PTTs) are commonly used to estimate the location and volume of nonaqueous-phase liquids (NAPLs) at contaminated groundwater sites. PTTs are completed before and after remediation efforts as one means to assess remediation effectiveness. PTT design is complex. Numerical models are invaluable tools for designing a PTT, particularly for designing flow rates and selecting tracers to ensure proper tracer breakthrough times, spatial design of injection-extraction wells and rates to maximize tracer capture, well-specific sampling density and frequency, and appropriate tracer-chemical masses. Generally, the design requires consideration of the following factors: type of contaminant; distribution of contaminant at the site, including location of hot spots; site hydraulic characteristics; measurement of the partitioning coefficients for the various tracers; the time allotted to conduct the PTT; evaluation of the magnitude and arrival time of the tracer breakthrough curves; duration of the tracer input pulse; maximum tracer concentrations; analytical detection limits for the tracers; estimation of the capture zone of the well field to tracer ensure mass balance and to limit residual tracer concentrations left in the subsurface; effect of chemical remediation agents on the PTT results, and disposal of the extracted tracer solution. These design principles are applied to a chemical-enhanced remediation effort for a chlorinated-solvent dense NAPL (DNAPL) site at Little Creek Naval Amphibious Base in Virginia Beach, Virginia. For this project, the hydrology and pre-PTT contaminant distribution were characterized using traditional methods (slug tests, groundwater and soil concentrations from monitoring wells, and geoprobe analysis), as well as membrane interface probe analysis. Additional wells were installed after these studies. Partitioning tracers were selected based on the primary DNAPL contaminants at the site, expected NAPL saturations

  1. The Impact of Well-Field Configuration and Permeability Heterogeneity on Contaminant Mass Removal and Plume Persistence

    NASA Astrophysics Data System (ADS)

    Guo, Z.; Brusseau, M. L.

    2015-12-01

    The purpose of this study is to investigate the effects of well-field hydraulics and permeability heterogeneity on mass-removal efficiency for systems comprising large groundwater contaminant plumes. A three-dimensional (3D) numerical model was used to simulate the impact of different well-field configurations on pump-and-treat mass removal for heterogeneous domains. The relationship between reduction in contaminant mass discharge (CMDR) and mass removal (MR) was used as the metric to examine remediation efficiency. The impacts of well-field configuration on mass removal behavior is attributed to mass-transfer constraints associated with regions of low flow, which can be muted by the influence of permeability heterogeneity. These impacts are reflected in the associated CMDR-MR profiles. Systems whose CDMR-MR profiles are below the 1:1 relationship line are associated with more efficient well-field configurations. The impact of domain heterogeneity on mass-removal effectiveness was investigated in terms of both variance and correlation scale of the random permeability distributions and indexed by the CMDR-MR relationship. Data collected from pump-and-treat operations conducted in a section of the Tucson International Airport Area (TIAA) federal Superfund site were used as a case study. The comparison between simulated and measured site data supports the general validity of the numerical model, and results from the case study are consistent with the conclusions of the theoretical study. These results illustrate that the CMDR-MR relationship can be an effective way to quantify the impacts of different factors on mass-removal efficiency.

  2. Detecting and Removing Data Artifacts in Hadamard Transform Ion Mobility-Mass Spectrometry Measurements

    SciTech Connect

    Prost, Spencer A.; Crowell, Kevin L.; Baker, Erin Shammel; Ibrahim, Yehia M.; Clowers, Brian H.; Monroe, Matthew E.; Anderson, Gordon A.; Smith, Richard D.; Payne, Samuel H.

    2014-05-06

    Applying Hadamard transform multiplexing to ion mobility separations (IMS) can significantly improve the signal-to-noise ratio and throughput for IMS coupled mass spectrometry (MS) measurements by increasing the ion utilization efficiency. However, it has been determined that both fluctuations in ion intensity as well as spatial shifts in the multiplexed data lower the signal-to-noise ratios and appear as noise in downstream processing of the data. To address this problem, we have developed a novel algorithm that discovers and eliminates data artifacts. The algorithm uses knowledge of the true signal peaks derived from the encoded data and allows for both artifacts and noise to be removed with high confidence, decreasing the likelihood of false identifications in subsequent data processing. The result is that IMS-MS can be applied to increase measurement sensitivity while avoiding artifacts that have previously limited its utility.

  3. Detecting and Removing Data Artifacts in Hadamard Transform Ion Mobility-Mass Spectrometry Measurements

    DOE PAGES

    Prost, Spencer A.; Crowell, Kevin L.; Baker, Erin Shammel; ...

    2014-05-06

    Applying Hadamard transform multiplexing to ion mobility separations (IMS) can significantly improve the signal-to-noise ratio and throughput for IMS coupled mass spectrometry (MS) measurements by increasing the ion utilization efficiency. However, it has been determined that both fluctuations in ion intensity as well as spatial shifts in the multiplexed data lower the signal-to-noise ratios and appear as noise in downstream processing of the data. To address this problem, we have developed a novel algorithm that discovers and eliminates data artifacts. The algorithm uses knowledge of the true signal peaks derived from the encoded data and allows for both artifacts andmore » noise to be removed with high confidence, decreasing the likelihood of false identifications in subsequent data processing. The result is that IMS-MS can be applied to increase measurement sensitivity while avoiding artifacts that have previously limited its utility.« less

  4. A gas chromatography-mass spectrometry method to monitor detergents removal from a membrane protein sample.

    PubMed

    Shi, Chaowei; Han, Fang; Xiong, Ying; Tian, Changlin

    2009-12-01

    In membrane protein biochemical and structural studies, detergents are used to mimic membrane environment and maintain functional, stable conformation of membrane proteins in the absence of lipid bilayers. However, detergent concentration, esp. molar ratio of membrane protein to detergent is usually unknown. Here, a gas chromatography-mass spectrometry selected ion monitoring (GC-MS-SIM) method was developed to quantify four detergents which are frequently used in membrane protein structural studies. To remove excessive detergents, a filtered centrifugation using Centricon tubes was applied. A membrane protein Ig-Beta fragment in four different detergent micelles was exemplified. Detergent concentrations in the upper and lower fraction of the Centricon tube were measured after each round of centrifugation. The results were very consistent to basic properties of detergent micelles in aqueous solvents. Therefore, coupling of GC-MS-SIM and detergent removal by Centricon tubes, detergents concentration, esp. molar ratio of membrane protein to detergent could be controlled, which will expedite membrane protein structural and biochemical studies.

  5. A Comparative Study of Mass Removal Loads for a Range of Stormwater Treatment Strategies

    NASA Astrophysics Data System (ADS)

    Avellaneda, P. M.; Houle, J. J.; Roseen, R. M.; Ballestero, T. P.

    2005-05-01

    When evaluating performance efficiencies for stormwater BMPs, there are significant challenges with regards to normalizing the variations in design, and hydraulic and hydrological conditions. There can be significant variations that must be considered such as rainfall intensity and duration, influent quality, watershed characteristics, loading functions, antecedent dry period, and maintenance. This study assessed mass removal loads for different stormwater management measures, all located in the same facility. The research facility is unique because it enables monitoring of 12 different treatment devices in parallel. For this purpose, a 9-acre commuter parking lot at the University of New Hampshire was chosen to provide runoff. There are three classes of devices examined at the site, conventional structural Best Management Practices (BMP), Low Impact Development (LID) designs, and manufactured devices. These include a subsurface gravel wetland, a detention pond, a sand filter, a bioretention system, a vegetated swale, and 7 different manufactured devices. Flow was evenly distributed and piped to each stormwater treatment. An on-site rain gauge provided rainfall data and samples of stormwater influent and effluent (for each stormwater treatment) were collected during monitoring rainfall events between August (2004) and April (2005). Temperature, dissolved oxygen and conductivity were measured continuously. Runoff constituents such as TSS, TP, TN, Cu, metals, nutrients and bacteria were measured in temporal water samples for each monitoring rainfall event. Results are presented as both concentration and Event Mean Concentrations (EMCs) to evaluate mass load removal. The watershed rainfall-runoff pattern was investigated as well as a statistical analysis to determine whether or not the differences between inflow and effluent water quality parameters were statistically significant. Earlier results have shown significant differences in the effluent water quality

  6. Enhanced mass removal due to phase explosion during high irradiance nanosecond laser ablation of silicon

    SciTech Connect

    Yoo, Jong Hyun

    2000-05-01

    The morphology of craters resulting from high irradiance laser ablation of silicon was measured using a white light interferometry microscope. The craters show a dramatic increase in their depth and volume at a certain irradiance, indicating a change in the primary mechanism for mass removal. Laser shadowgraph imaging was used to characterize and differentiate the mass ejection processes for laser irradiances above and below the threshold value. Time-resolved images show distinct features of the mass ejected at irradiances above the threshold value including the presence of micron-sized particulates; this begins at approximately 300 ~ 400 ns after the start of laser heating. The analysis of the phenomena was carried out by using two models: a thermal evaporation model and a phase explosion model. Estimation of the crater depth due to the thermally evaporated mass led to a large underestimation of the crater depth for irradiances above the threshold. Above the threshold irradiance, the possibility of phase explosion was analyzed. Two important results are the thickness of the superheated liquid layer that is close to the critical temperature and the time for vapor bubbles that are generated in the superheated liquid to achieve a critical size. After reaching the critical size, vapor bubbles can grow spontaneously resulting in a violent ejection of liquid droplets from the superheated volume. The effects of an induced transparency, i.e. of liquid silicon turning into an optically transparent liquid dielectric medium, are also introduced. The estimated time for a bubble to reach the critical size is in agreement with the delay time measured for the initiation of large mass ejection. Also, the thickness of the superheated liquid layer that is close to the critical temperature at the time of the beginning of the large mass ejection is representative of the crater depth at the threshold irradiance. These results suggest that phase explosion is a plausible thermal

  7. DOE-EMSP Final Report: Characterization of Changes in Colloid and DNAPL Affecting Surface Chemistry and Remediation

    SciTech Connect

    Susan E. Powers; Stefan J. Grimberg; Miles Denham

    2007-02-07

    The waste disposal to the M-area basin and A-14 outfall at the Savannah River Department of Energy facility in Aiken SC (USA) included a wide variety of inorganic aqueous flows and organic solvents in the form of dense non-aqueous phase liquids (DNAPL). The DNAPL has migrated through the subsurface resulting in widespread groundwater contamination. The goal of this research was to identify and quantify processes that could have affected the migration and remediation of the DNAPL in the subsurface. It was hypothesized that the variety of waste disposed at this site could have altered the mineral, microbial and DNAPL properties at this site relative to other DNAPL sites. The DNAPL was determined to have a very low interfacial tension and is suspected to be distributed in fine grained media, thereby reducing the effectiveness of soil vapor extraction remediation efforts. Although the DNAPL is primarily comprised of tetrachloroethene and trichloroethane, it also contains organic acids and several heavy metals. Experimental results suggest that iron from the aqueous and DNAPL phases undergoes precipitation and dechlorination reactions at the DNAPL-water interface, contributing to the low interfacial tension and acidity of the DNAPL. Biological activity in the contaminated region can also contribute to the low interfacial tension. PCE degrading bacteria produce biosurfactants and adhere to the DNAPL-water interface when stressed by high tetrachloroethene or low dissolved oxygen concentrations. The presence of iron can reduce the interfacial tension by nearly an order of magnitude, while the PCE degraders reduced the interfacial tension by nearly 50%. Abiotic changes in the mineral characteristics were not found to be substantially different between contaminated and background samples. The research completed here begins to shed some insight into the complexities of DNAPL fate and migration at sites where co-disposal of many different waste products occurred. Quantifying

  8. DNAPL characterization using the Ribbon NAPL sampler: Methods and results

    SciTech Connect

    Riha, B.D.

    2000-04-25

    The Ribbon NAPL Sampler (RNS) is a direct sampling device that provides detailed depth discrete mapping of Non Aqueous Phase Liquids (NAPLs) in a borehole. This characterization method provides a yes or no answer to the presence of NAPLs and is used to complement and enhance other characterization techniques. Several cone penetrometer deployment methods are in use and methods for other drilling techniques are under development. The RNS has been deployed in the vadose and saturated zones at four different sites. Three of the sites contain DNAPLs from cleaning and degreasing operations and the fourth site contains creosote from a wood preserving plant. A brief description of the process history and geology is provided for each site. Where available, lithology and contaminant concentration information is provided and discussed in context with the RNS results.

  9. Ultrasonic properties of granular media saturated with dnapl/watermixtures

    SciTech Connect

    Ajo-Franklin, J.B.; Geller, J.T.; Harris, J.M.

    2007-09-15

    We present the results of four experiments investigating the ultrasonic properties of granular materials partially saturated with trichloroethylene (TCE), a dense non-aqueous contaminant. P-wave velocity measurements were made under in situ effective stress conditions using a pulse transmission cell at ?250 kHz. Two synthetic samples and two natural aquifer cores were fully saturated with water and then subjected to an axial injection of TCE. The resulting measurements show reductions in P-wave velocity of up to 15% due to contaminant saturation. A theoretical model combining Gassmann fluid substitution and Hill's equation was used to estimate the effects of DNAPL saturation; this model underpredicted observed reductions in velocity at high TCE saturations. A linear relationship, expressed in terms of volumetric contaminant fraction, provided an excellent empirical fit to the laboratory measurements.

  10. Ensemble of Surrogates-based Optimization for Identifying an Optimal Surfactant-enhanced Aquifer Remediation Strategy at Heterogeneous DNAPL-contaminated Sites

    NASA Astrophysics Data System (ADS)

    Lu, W., Sr.; Xin, X.; Luo, J.; Jiang, X.; Zhang, Y.; Zhao, Y.; Chen, M.; Hou, Z.; Ouyang, Q.

    2015-12-01

    The purpose of this study was to identify an optimal surfactant-enhanced aquifer remediation (SEAR) strategy for aquifers contaminated by dense non-aqueous phase liquid (DNAPL) based on an ensemble of surrogates-based optimization technique. A saturated heterogeneous medium contaminated by nitrobenzene was selected as case study. A new kind of surrogate-based SEAR optimization employing an ensemble surrogate (ES) model together with a genetic algorithm (GA) is presented. Four methods, namely radial basis function artificial neural network (RBFANN), kriging (KRG), support vector regression (SVR), and kernel extreme learning machines (KELM), were used to create four individual surrogate models, which were then compared. The comparison enabled us to select the two most accurate models (KELM and KRG) to establish an ES model of the SEAR simulation model, and the developed ES model as well as these four stand-alone surrogate models was compared. The results showed that the average relative error of the average nitrobenzene removal rates between the ES model and the simulation model for 20 test samples was 0.8%, which is a high approximation accuracy, and which indicates that the ES model provides more accurate predictions than the stand-alone surrogate models. Then, a nonlinear optimization model was formulated for the minimum cost, and the developed ES model was embedded into this optimization model as a constrained condition. Besides, GA was used to solve the optimization model to provide the optimal SEAR strategy. The developed ensemble surrogate-optimization approach was effective in seeking a cost-effective SEAR strategy for heterogeneous DNAPL-contaminated sites. This research is expected to enrich and develop the theoretical and technical implications for the analysis of remediation strategy optimization of DNAPL-contaminated aquifers.

  11. Ensemble of surrogates-based optimization for identifying an optimal surfactant-enhanced aquifer remediation strategy at heterogeneous DNAPL-contaminated sites

    NASA Astrophysics Data System (ADS)

    Jiang, Xue; Lu, Wenxi; Hou, Zeyu; Zhao, Haiqing; Na, Jin

    2015-11-01

    The purpose of this study was to identify an optimal surfactant-enhanced aquifer remediation (SEAR) strategy for aquifers contaminated by dense non-aqueous phase liquid (DNAPL) based on an ensemble of surrogates-based optimization technique. A saturated heterogeneous medium contaminated by nitrobenzene was selected as case study. A new kind of surrogate-based SEAR optimization employing an ensemble surrogate (ES) model together with a genetic algorithm (GA) is presented. Four methods, namely radial basis function artificial neural network (RBFANN), kriging (KRG), support vector regression (SVR), and kernel extreme learning machines (KELM), were used to create four individual surrogate models, which were then compared. The comparison enabled us to select the two most accurate models (KELM and KRG) to establish an ES model of the SEAR simulation model, and the developed ES model as well as these four stand-alone surrogate models was compared. The results showed that the average relative error of the average nitrobenzene removal rates between the ES model and the simulation model for 20 test samples was 0.8%, which is a high approximation accuracy, and which indicates that the ES model provides more accurate predictions than the stand-alone surrogate models. Then, a nonlinear optimization model was formulated for the minimum cost, and the developed ES model was embedded into this optimization model as a constrained condition. Besides, GA was used to solve the optimization model to provide the optimal SEAR strategy. The developed ensemble surrogate-optimization approach was effective in seeking a cost-effective SEAR strategy for heterogeneous DNAPL-contaminated sites. This research is expected to enrich and develop the theoretical and technical implications for the analysis of remediation strategy optimization of DNAPL-contaminated aquifers.

  12. A DNAPL emergency remedial action program in a developing country: Part II

    SciTech Connect

    Nobre, M.M. . Dept. of Geology); Daus, A.D. )

    1993-10-01

    At the 44th Annual National Ground Water Association Convention in Las Vegas, a poster was presented that described a large DNAPL ground-water contamination problem at an industrial complex that produces chlorinated hydrocarbons in Brazil. The industrial complex lies above a major drinking water aquifer. Ground-water monitoring wells were installed in an effort to define the extent of the dissolve-phase ground-water plume. Field and laboratory data were analyzed, a ground-water flow model was developed, and a feasibility study was conducted to identify, evaluate, and select emergency interim remedial measures. Interim remedial measures were implemented less than six months from installation of the first monitoring well and included ground-water extraction and treatment to provide hydraulic control of the plume and prevent further migration of contaminants to downgradient receptors. In the subsequent year since the first interim ground-water extraction well was installed a number of key tasks have been completed. Ground-water extraction and monitoring identified a preferred pathway for contaminant migration. The remedial strategy for the site includes developing an efficient ground-water hydraulic control program based on collapse of the plume width and shortening the overall plume length (in progress). After an efficient hydraulic control program has been installed and verified, efforts will focus on source mass reduction. Long-term hydraulic control is anticipated to be an integral part of the remediation program.

  13. Petroleum mass removal from low permeability sediment using air sparging/soil vapor extraction: impact of continuous or pulsed operation

    NASA Astrophysics Data System (ADS)

    Kirtland, Brian C.; Aelion, C. Marjorie

    2000-02-01

    Air sparging and soil vapor extraction (AS/SVE) are innovative remediation techniques that utilize volatilization and microbial degradation to remediate petroleum spills from soils and groundwater. This in situ study investigated the use of AS/SVE to remediate a gasoline spill from a leaking underground storage tank (UST) in the low permeability, clayey soil of the Appalachian Piedmont. The objectives of this study were to evaluate AS/SVE in low permeability soils by quantifying petroleum mass removal rates, monitoring vadose zone contaminant levels, and comparing the mass extraction rates of continuous AS/SVE to 8 and 24 h pulsed operation. The objectives were met by collecting AS/SVE exhaust gas samples and vadose zone air from multi-depth soil vapor probes. Samples were analyzed for O 2, CO 2, BTEX (benzene, toluene, ethylbenzene, xylene), and total combustible hydrocarbon (TCH) concentrations using portable hand meters and gas chromatography. Continuous AS/SVE was effective in removing 608 kg of petroleum hydrocarbons from low permeability soil in 44 days (14.3 kg day -1). Mass removal rates ranged from 2.6 times higher to 5.1 times lower than other AS/SVE studies performed in sandy sediments. BTEX levels in the vadose zone were reduced from about 5 ppm to 1 ppm. Ten pulsed AS/SVE tests removed 78 kg in 23 days and the mean mass removal rate (17.6 kg day -1) was significantly higher than the last 15 days of continuous extraction. Pulsed operation may be preferable to continuous operation because of increased mass removal and decreased energy consumption.

  14. Unique Interfacial Properties of the Chlorinated Solvent DNAPL at Savannah River National Laboratory

    SciTech Connect

    Powers, S.E.; Omrane, K.; Grimberg, S.J.

    2004-03-31

    Tetrachloroethene and trichloroethene are the primary constituents in a DNAPL found in the unsaturated zone at the Department of Energy's Savannah River Site (SRS). Following equilibration of the SRS DNAPL with deionized water, the measured interfacial tension was less than 2 dynes/cm and the pH of the aqueous phase 3.8, thus indicating the presence of constituents other than chlorinated solvents. Based on contamination history at DOE facilities, we explored the potential for co-contamination by oils, surfactants or organic acids. Non-aqueous potentiometric titration techniques revealed a high acid content (4 mg (as KOH)/g of DNAPL). Surrogate mixtures of TCE with the hydraulic oil, dibutylbutylphosphonate (DBBP) and tributylphosphate (TBP), which were used in the plutonium production process, also had low interfacial tension but not as low as the value measured for the SRS DNAPL. Research to identify the constituents and mechanisms responsible for the low interfacial tension of this DNAPL is on-going.

  15. NON-INVASIVE DETERMINATION OF THE LOCATION AND DISTRIBUTION OF FREE-PHASE DENSE NONAQUEOUS PHASE LIQUIDS (DNAPL) BY SEISMIC REFLECTION TECHNIQUES

    SciTech Connect

    Michael G. Waddell; William J. Domoracki; Tom J. Temples

    2001-12-01

    This annual technical progress report is for part of Task 4 (site evaluation), Task 5 (2D seismic design, acquisition, and processing), and Task 6 (2D seismic reflection, interpretation, and AVO analysis) on DOE contact number DE-AR26-98FT40369. The project had planned one additional deployment to another site other than Savannah River Site (SRS) or DOE Hanford Site. After the SUBCON midyear review in Albuquerque, NM, it was decided that two additional deployments would be performed. The first deployment is to test the feasibility of using non-invasive seismic reflection and AVO analysis as a monitoring tool to assist in determining the effectiveness of Dynamic Underground Stripping (DUS) in removal of DNAPL. The second deployment is to the Department of Defense (DOD) Charleston Naval Weapons Station Solid Waste Management Unit 12 (SWMU-12), Charleston, SC to further test the technique to detect high concentrations of DNAPL. The Charleston Naval Weapons Station SWMU-12 site was selected in consultation with National Energy Technology Laboratory (NETL) and DOD Naval Facilities Engineering Command Southern Division (NAVFAC) personnel. Based upon the review of existing data and due to the shallow target depth, the project team collected three Vertical Seismic Profiles (VSP) and an experimental P-wave seismic reflection line. After preliminary data analysis of the VSP data and the experimental reflection line data, it was decided to proceed with Task 5 and Task 6. Three high resolution P-wave reflection profiles were collected with two objectives; (1) design the reflection survey to image a target depth of 20 feet below land surface to assist in determining the geologic controls on the DNAPL plume geometry, and (2) apply AVO analysis to the seismic data to locate the zone of high concentration of DNAPL. Based upon the results of the data processing and interpretation of the seismic data, the project team was able to map the channel that is controlling the DNAPL plume

  16. The Vapor-phase Multi-stage CMD Test for Characterizing Contaminant Mass Discharge Associated with VOC Sources in the Vadose Zone: Application to Three Sites in Different Lifecycle Stages of SVE Operations

    PubMed Central

    Brusseau, M.L.; Mainhagu, J.; Morrison, C.; Carroll, K.C.

    2015-01-01

    Vapor-phase multi-stage contaminant mass discharge (CMD) tests were conducted at three field sites to measure mass discharge associated with contaminant sources located in the vadose zone. The three sites represent the three primary stages along the soil vapor extraction (SVE) operations lifecycle- pre/initial-SVE, mid-lifecycle, and near-closure. A CMD of 32 g/d was obtained for a site at which soil vapor SVE has been in operation for approximately 6 years, and for which mass removal is currently in the asymptotic stage. The contaminant removal behavior exhibited for the vapor extractions conducted at this site suggests that there is unlikely to be a significant mass of non-vapor-phase contaminant (e.g., DNAPL, sorbed phase) remaining in the advective domains, and that most remaining mass is likely located in poorly accessible domains. Given the conditions for this site, this remaining mass is hypothesized to be associated with the low-permeability (and higher water saturation) region in the vicinity of the saturated zone and capillary fringe. A CMD of 25 g/d was obtained for a site wherein SVE has been in operation for several years but concentrations and mass-removal rates are still relatively high. A CMD of 270 g/d was obtained for a site for which there were no prior SVE operations. The behavior exhibited for the vapor extractions conducted at this site suggest that non-vapor-phase contaminant mass (e.g., DNAPL) may be present in the advective domains. Hence, the asymptotic conditions observed for this site most likely derive from a combination of rate-limited mass transfer from DNAPL (and sorbed) phases present in the advective domain as well as mass residing in lower-permeability (“non-advective”) regions. The CMD values obtained from the tests were used in conjunction with a recently developed vapor-discharge tool to evaluate the impact of the measured CMDs on groundwater quality. PMID:26047819

  17. Suspected bilateral phrenic nerve damage following a mediastinal mass removal in a 17-week-old pug.

    PubMed

    Raillard, Mathieu; Murison, Pamela J; Doran, Ivan P

    2017-03-01

    The anesthetic management of a pediatric pug for removal of a mediastinal mass is described. During recovery from anesthesia, the dog's respiratory pattern was compatible with bilateral diaphragmatic paralysis. Incidence, complications, possible treatments of phrenic nerve injury, problems of long-term mechanical ventilation, and alternative case management are discussed.

  18. Use of 222Rn as a natural tracer to evaluate the efficiency of flushing test at DNAPL contaminated area

    NASA Astrophysics Data System (ADS)

    Lee, S.; Joun, W.; Kim, H.; Kaown, D.; Lee, K.

    2013-12-01

    Flushing test was applied to remediate the depth-discrete residual dense non-aqueous phase liquid (DNAPL) sources in an unsaturated zone at an industrial complex in Wonju, Korea. Remediation efficiency for flushing test was evaluated by comparing the natural tracer 222Rn concentration data in groundwater and the mass discharges of trichloroethylene (TCE) through a cross section before and during the test period. In the previous research performed at the study site, the location of residual DNAPL sources in the unsaturated zone was identified using the natural tracer 222Rn and contaminant concentrations based on the information for characteristics of radon which was partitioning into TCE. The natural injection method and pressurized injection method were applied for water injection. Uncontaminated groundwater around main source area was used as injection water. Temporal and spatial monitoring results show that a combined water injection (conducting both natural injection and pressurization injection) is an effective operation method. The 222Rn activities and TCE concentrations in groundwater fluctuated irregularly with water level increase at the main source area. The natural tracer 222Rn in groundwater originating from the underlying crystalline biotite granite, had a wide range from 15,000 to 183,000 Bq/m3 and total concentrations of TCE ranged from 0.03 to 1.79 mg/l. These temporal variations in 222Rn activities might be caused by not only the unknown quantities of residual TCE in the unsaturated zone but also the characteristics of radon partitioning into residual TCE with water level increase. From these results, the 222Rn activities could not be used directly as a natural tracer to evaluate the remediation efficiency due to the irregular production. Therefore, for more precise efficiency evaluation, the comparative analysis between 222Rn activities and relative contaminant concentrations data is required.

  19. Permanganate Treatment of DNAPLs in Reactive Barriers and Source Zone Flooding Schemes - Final Report

    SciTech Connect

    Schwartz, F.W.

    2000-10-01

    This study provides a detailed process-level understanding of the oxidative destruction of the organic contaminant emphasizing on reaction pathways and kinetics. A remarkable rise in the MnO{sup {minus}} consumption rate with TCA and PCE mixtures proves that the phase transfer catalysts have the ability to increase oxidation rate of DNAPLs either in pure phase or mixtures and that there is significant potential for testing the catalyzed scheme under field conditions. Secondly, as an attempt to enhance the oxidation of DNAPL, we are trying to exploit cosolvency effects, utilizing various alcohol-water mixtures to increase DNAPL solubilization. Preliminary results of cosolvency experiments indicate the enhancement in the transfer of nonaqueous phase TCE to TBA-water solution and the rate of TCE degradation in aqueous phase.

  20. Effects of soil layering and interfacial tension on DNAPL migration in subsurface environments

    SciTech Connect

    Singletary, M.A.; Pennell, K.D.; Ramsburg, A.

    1999-07-01

    A series of tetrachloroethene (PCE) infiltration experiments was conducted in 2-dimensional aquifer cells to investigate the effects of soil layering and interfacial tension on dense non-aqueous phase liquid (DNAPL) infiltration and entrapment in saturated environments. The aquifer cells were packed with a background medium, 20--30 mesh Ottawa sand, and a single low-permeability layer, consisting of either F-70 Ottawa sand or Wurtsmith aquifer material, located near the center of the cell. PCE was introduced approximately 5 cm below the water table at a constant flow rate of 0.05 ml/min. The results of these experiments demonstrate the dramatic effects that interfacial tension reduction can have on DNAPL flow and entrapment in layered subsurface systems. These findings also have implications during field implementation of surfactant enhanced aquifer remediation (SEAR), in which low interfacial tension surfactant formulations may lead to DNAPL migration into fine layers or previously uncontaminated regions of an aquifer.

  1. Evaluation of the likelihood of DNAPL presence at NPL sites: National results. Final report

    SciTech Connect

    Not Available

    1993-09-01

    The document presents the results of a survey undertaken by the U.S. Environmental Protection Agency's (EPA's) Office of Emergency and Remedial Response (Superfund). The survey was designed to estimate the proportion of National Priorities List (NPL) sites where Dense Nonaqueous Phase Liquids (DNAPLs) may be present. Earlier studies by OERR suggested that DNAPLs may be more common at hazardous waste sites than previously thought, and may act as a continuing source of contamination thus reducing the ability of pump-and-treat systems to attain cleanup goals within expected timeframes (Evaluation of Ground Water Extraction Remedies, Phase II, EPA 9355.4-05). The study represents the first systematic nation-wide review of NPL sites designed to estimate the extent of subsurface DNAPL contamination.

  2. In situ oxidation and associated mass-flux-reduction/mass-removal behavior for systems with organic liquid located in lower-permeability sediments.

    PubMed

    Marble, Justin C; Carroll, Kenneth C; Janousek, Hilary; Brusseau, Mark L

    2010-09-20

    The effectiveness of permanganate for in situ chemical oxidation of organic liquid (trichloroethene) trapped in lower-permeability (K) zones located within a higher-permeability matrix was examined in a series of flow-cell experiments. The permanganate solution was applied in both continuous and pulsed-injection modes. Manganese-oxide precipitation, as confirmed by use of SEM-EDS, occurred within, adjacent to, and downgradient of the lower-K zones, reflective of trichloroethene oxidation. During flow interruptions, precipitate formed within the surrounding higher-permeability matrix, indicating diffusive flux of aqueous-phase trichloroethene from the lower-K zones. The impact of permanganate treatment on mass flux behavior was examined by conducting water floods after permanganate injection. The results were compared to those of water-flood control experiments. The amount of water flushing required for complete contaminant mass removal was reduced for all permanganate treatments for which complete removal was characterized. However, the nature of the mass-flux-reduction/mass-removal relationship observed during water flooding varied as a function of the specific permanganate treatment.

  3. In Situ Oxidation and Associated Mass-Flux-Reduction/Mass-Removal Behavior for Systems with Organic Liquid Located in Lower-Permeability Sediments

    SciTech Connect

    Marble, justin C.; Carroll, Kenneth C.; Janousek, Hilary; Brusseau, M. L.

    2010-07-21

    The effectiveness of permanganate for in situ chemical oxidation of organic liquid (trichloroethene) trapped in lower-permeability (K) zones located within a higher-permeability matrix was examined in a series of flow-cell experiments. The permanganate solution was applied in both continuous and pulsed-injection modes. Manganese-oxide precipitation, as confirmed by use of SEM-EDS, occurred within, adjacent to, and downgradient of the lower-K zones, reflective of trichloroethene oxidation. During flow interruptions, precipitate formed within the surrounding higher-permeability matrix, indicating diffusive flux of aqueous-phase trichloroethene from the lower-K zones. The impact of permanganate treatment on mass flux behavior was examined by conducting water floods after permanganate injection. The results were compared to those of water-flood control experiments. The amount of water flushing required for complete contaminant mass removal was reduced for all permanganate treatments for which complete removal was characterized. However, the nature of the mass-flux-reduction/mass-removal relationship observed during water flooding varied as a function of the specific permanganate treatment.

  4. Comparison of dechlorination rates for field DNAPL vs synthetic samples: effect of sample matrix

    NASA Astrophysics Data System (ADS)

    O'Carroll, D. M.; Sakulchaicharoen, N.; Herrera, J. E.

    2015-12-01

    Nanometals have received significant attention in recent years due to their ability to rapidly destroy numerous priority source zone contaminants in controlled laboratory studies. This has led to great optimism surrounding nanometal particle injection for insitu remediation. Reported dechlorination rates vary widely among different investigators. These differences have been ascribed to differences in the iron types (granular, micro, or nano-sized iron), matrix solution chemistry and the morphology of the nZVI surface. Among these, the effects of solution chemistry on rates of reductive dechlorination of various chlorinated compounds have been investigated in several short-term laboratory studies. Variables investigated include the effect of anions or groundwater solutes such as SO4-2, Cl-, NO3-, pH, natural organic matters (NOM), surfactant, and humic acid on dechlorination reaction of various chlorinated compounds such as TCE, carbon tetrachloride (CT), and chloroform (CF). These studies have normally centered on the assessment of nZVI reactivity toward dechlorination of an isolated individual contaminant spiked into a ground water sample under ideal conditions, with limited work conducted using real field samples. In this work, the DNAPL used for the dechlorination study was obtained from a contaminatied site. This approach was selected to adequately simulate a condition where the nZVI suspension was in direct contact with DNAPL and to isolate the dechlorination activity shown by the nZVI from the groundwater matrix effects. An ideal system "synthetic DNAPL" composed of a mixture of chlorinated compounds mimicking the composition of the actual DNAPL was also dechlorinated to evaluate the DNAPL "matrix effect" on NZVI dechlorination activity. This approach allowed us to evaluate the effect of the presence of different types of organic compounds (volatile fatty acids and humic acids) found in the actual DNAPL on nZVI dechlorination activity. This presentation will

  5. Laboratory and pilot field-scale testing of surfactants for environmental restoration of chlorinated solvent DNAPLs

    SciTech Connect

    Jackson, R.E.; Fountain, J.C.

    1994-12-31

    This project is composed of two phases and has the objective of demonstrating surfactant-enhanced aquifer remediation (SEAR) as a practical remediation technology at DOE sites with ground water contaminated by dense, non-aqueous phase liquids (DNAPLs), in particular, chlorinated solvents. The first phase of this project, Laboratory and Pilot Field Scale Testing, which is the subject of the work so far, involves (1) laboratory experiments to examine the solubilization of multiple component DNAPLs, e.g., solvents such as perchloroethylene (PCE) and trichloroethylene (TCE), by dilute surfactant solutions, and (2) a field test to demonstrate SEAR technology on a small scale and in an existing well.

  6. Online matrix removal platform for coupling gel-based separations to whole protein electrospray ionization mass spectrometry.

    PubMed

    Kim, Ki Hun; Compton, Philip D; Tran, John C; Kelleher, Neil L

    2015-05-01

    A fractionation method called gel-eluted liquid fraction entrapment electrophoresis (GELFrEE) has been used to dramatically increase the number of proteins identified in top-down proteomic workflows; however, the technique involves the use of sodium dodecyl sulfate (SDS), a surfactant that interferes with electrospray ionization. Therefore, an efficient removal of SDS is absolutely required prior to mass analysis. Traditionally, methanol/chloroform precipitation and spin columns have been used, but they lack reproducibility and are difficult to automate. Therefore, we developed an in-line matrix removal platform to enable the direct analysis of samples containing SDS and salts. Only small molecules like SDS permeate a porous membrane and are removed in a manner similar to cross-flow filtration. With this device, near-complete removal of SDS is accomplished within 5 min and proteins are subsequently mobilized into a mass spectrometer. The new platform was optimized for the analysis of GELFrEE fractions enriched for histones extracted from human HeLa cells. All four core histones and their proteoforms were detected in a single spectrum by high-resolution mass spectrometry. The new method versus protein precipitation/resuspension showed 2- to 10-fold improved signal intensities, offering a clear path forward to improve proteome coverage and the efficiency of top-down proteomics.

  7. Site characterization for DNAPL contamination: An evolutionary process

    SciTech Connect

    Nussbaum, R.A. . Hazardous Waste Program)

    1993-03-01

    Kerr-McGee Chemical Corporation and its predecessor operated a pressure-type creosote wood preserving facility in Kansas City, Missouri, from 1907--1983. The facility property is approximately 104 acres in size and is located in the flood plain of the Blue River. Investigation of subsurface contamination of the blue River alluvium related to releases from waste management units (e.g., former surface impoundment used for wastewater treatment, wood treating process/kickback area) at the site has been evolutionary process driven by the regulatory requirements of the Resource Conservation and Recovery Act (RCRA). Site investigation techniques have ranged from initial installation of rudimentary boreholes/monitoring wells to assess gross lithology/groundwater quality to recent use of an extensive Cone Penetrometer Survey (CPS) to refine interactions. Although the site-wide characterization has not yet been completed, knowledge gained through the evolutionary investigation process has been used successfully to guide decisions concerning interim remedial measures (e.g., placement of wells for recovery of DNAPL) and should allow for expedient, focused development of additional site investigation and long-term remedial action work plans.

  8. Destruction of 1,1,1-trichloroethane and 1,2-dichloroethane DNAPLs by catalyzed H2O2 propagations (CHP).

    PubMed

    Smith, Brant A; Teel, Amy L; Watts, Richard J

    2015-01-01

    Catalyzed H2O2 propagations (CHP) was studied to treat 1,1,1-trichloroethane (TCA) and 1,1-dichloroethane (DCA) dense nonaqueous phase liquids (DNAPLs) and to elucidate the reactive oxygen species responsible for their destruction. A TCA DNAPL was rapidly destroyed by CHP at a rate 3.5 times greater than its maximum rate of dissolution. Using systems that generate a single reactive oxygen species, the species responsible for TCA DNAPL destruction was found to be superoxide. Both hydroxyl radical and superoxide were responsible for the destruction of the DCA DNAPL. Both compounds were destroyed at equal rates in a mixed TCA/DCA DNAPL, which suggests that the rate of treatment is limited by a surface phenomenon at the DNAPL-water interface. The optimum pH for the destruction of TCA and DCA DNAPLs was near the pKa of 4.8 for perhydroxyl radical-superoxide systems. The results of this research demonsrate that TCA and DCA DNAPLs are effectively destroyed by CHP and that superoxide generation is necessary for effective TCA DNAPL destruction, while both hydroxyl radical and superoxide are necessary for effective DCA DNAPL destruction.

  9. Exploration of the influence of coupled mass transfer processes on chlorinated solvent plume persistence in heterogeneous source zones

    NASA Astrophysics Data System (ADS)

    Yang, L.; Abriola, L. M.

    2016-12-01

    Restoration of source zones to EPA regulated levels has rarely been achieved at chlorinated solvent-contaminated sites. In addition to residual DNAPL, sequestered aqueous and sorbed phase mass in low permeability zones have been recognized as important secondary sources that can be released back into mobile plumes and sustain downgradient plume tailing. This study uses a modified version of MT3DMS to explore the influence of dissolution, sorption, and diffusion process coupling on source longevity and near-source plume persistence for an ensemble of complex field site realizations. Simulation results suggest that sorption/desorption processes will control the rate of reverse mass transport from low permeability zones to mobile regions. Inclusion of sorption and the selected sorption model, whether equilibrium or nonequilibrium, linear or nonlinear, are shown to influence plume persistence, especially for the post-DNAPL dissolution period. Comparison of selected 3-D and 2-D simulations reveals discrepancies in predictions of plume longevity. Simulation dimensionality is shown to be more important when the subsurface material sorption behavior is characterized as non-ideal. The heterogeneous distribution of the DNAPL saturation is demonstrated to strongly influence mass storage and release in low permeability regions. For example, fast depletion of neighboring DNAPL initiates the early release of sequestered mass in low permeability zones, and dominant transport processes vary locally in highly heterogeneous source regions. Simulations also suggest that the presence of small zones of entrapped DNAPL mass can easily be missed in the characterization of aged field sites, since low concentration plumes emanating from entrapped DNAPL mass can be interpreted as originating from other secondary sources. Indeed, for the examined scenarios, DNAPL dissolution processes tended to control plume tailing for 53-98% of the plume life, highlighting the importance of accounting for

  10. Mean and variance of DNAPL ringer development in a saturated, randomly heterogeneous porous medium.

    SciTech Connect

    Tartakovsky, A. M.; Neuman, S. P.; Tartakovsky, D. M.

    2001-01-01

    Chlorinated organic solvents such as TCE and PCE are among the most ubiquitous and problematic groundwater contaminants at many sites. They usually enter the subsurface in the form of organic liquids which exhibit low miscibility with water and thus form a separate dense non-aqueous phase liquid (DNAPL). Here we analyze the movement of DNAPL in a three-dimensional randomly heterogeneous porous medium saturated with water. We consider the fluid interface between DNAPL and water to form a sharp boundary at which the capillary pressure head, assumed equal to the entry pressure head of DNAPL, is prescribed either deterministically or randomly. We treat log hydraulic conductivity as a statistically homogeneous random field with given mean, variance and covariance, This allows us to cast the corresponding boundary-value problem in the form of an integro-differential equation, in which the parameters and domain of integration are random. Expanding this equation in a Taylor series about the mean position of the front, and averaging in probability space, yields leading-order ensemble I moment equations for the mean and variance of front evolution with time. Previously we solved these moment equations analytically in one-dimension with gravity, to first order in the variance of log conductivity, and compared our solution with the results of Monte Carlo sjmulations. Here we solve the same moment equations numerically in two-spatial dimensions without gravity.

  11. Characterizing The Microbial Community In A TCE DNAPL Site: SABRE Column And Field Studies

    EPA Science Inventory

    The SABRE (Source Area BioREmediation) project is evaluating accelerated anaerobic bioremediation of chlorinated solvents in areas of high concentration, such as DNAPL source areas. In support of a field scale pilot test, column studies were conducted to design the system and ob...

  12. FIELD EVALUATION OF THE TREATMENT OF DNAPL USING EMULSIFIED ZERO-VALENT IRON (Battelle Conference)

    EPA Science Inventory

    A pilot scale field demonstration of dense non-aqueous phase liquids (DNAPL) treatment using emulsified zero-valent iron (EZVI) was conducted at Parris Island Marine Corps Recruit Depot (MCRD), Parris Island, SC. The EZVI technology was developed at the University of Central Fl...

  13. A MODIFIED LIGHT TRANSMISSION VISUALIZATION METHOD FOR DNAPL SATURATION MEASUREMENTS IN 2-D MODELS

    EPA Science Inventory

    In this research, a light transmission visualization (LTV) method was used to quantify dense non-aqueous phase liquids (DNAPL) saturation in two-dimensional (2-D), two fluid phase systems. The method is an expansion of earlier LTV methods and takes into account both absorption an...

  14. ENHANCED CONTACT OF COSOLVENT AND DNAPL IN POROUS MEDIA BY CONCURRENT INJECTION OF COSOLVENT AND AIR

    EPA Science Inventory

    Remediation of sites contaminated by dense nonaqueous phase liquids (DNAPLS) is a major
    environmental problem and cosolvent flooding is proposed as a remedial alternative. The
    efficacy of cosolvent flooding is a function of the degree of mixing between the injected
    remed...

  15. Spatial And Temporal Distribution Of Microbial Communities In A TCE DNAPL Site: SABRE Field Studies

    EPA Science Inventory

    The SABRE (Source Area BioREmediation) project was conducted to evaluate accelerated anaerobic bioremediation of chlorinated solvents in areas of high concentration, such as DNAPL source areas. To study performance of this technology, a test cell was constructed with a longitudi...

  16. FIELD EVALUATION OF THE TREATMENT OF DNAPL USING EMULSIFIED ZERO-VALENT IRON (Battelle Conference)

    EPA Science Inventory

    A pilot scale field demonstration of dense non-aqueous phase liquids (DNAPL) treatment using emulsified zero-valent iron (EZVI) was conducted at Parris Island Marine Corps Recruit Depot (MCRD), Parris Island, SC. The EZVI technology was developed at the University of Central Fl...

  17. FIELD EVALUATION OF THE TREATMENT OF DNAPL USING EMULSIFIED ZERO-VALENT IRON

    EPA Science Inventory

    A pilot scale field demonstration of dense non-aqueous phase liquids (DNAPL) treatment using emulsified zero-valent iron (EZVI) is being conducted at Parris Island Marine Corps Recruit Depot (MCRD), Parris Island SC. The demonstration is being conducted by Geosyntec, the Nationa...

  18. FIELD EVALUATION OF THE TREATMENT OF DNAPL USING EMULSIFIED ZERO-VALENT IRON (BATTELLE PRESENTATION)

    EPA Science Inventory

    A pilot scale field demonstration of dense non-aqueous phase liquids (DNAPL) treatment using emulsified zero-valent iron (EZVI) is being conducted at Parris Island Marine Corps Recruit Depot (MCRD), Parris Island SC. The EZVI technology was developed at the University of Central ...

  19. Simulation of DNAPL migration in heterogeneous translucent porous media based on estimation of representative elementary volume

    NASA Astrophysics Data System (ADS)

    Wu, Ming; Wu, Jianfeng; Wu, Jichun

    2017-10-01

    When the dense nonaqueous phase liquid (DNAPL) comes into the subsurface environment, its migration behavior is crucially affected by the permeability and entry pressure of subsurface porous media. A prerequisite for accurately simulating DNAPL migration in aquifers is then the determination of the permeability, entry pressure and corresponding representative elementary volumes (REV) of porous media. However, the permeability, entry pressure and corresponding representative elementary volumes (REV) are hard to determine clearly. This study utilizes the light transmission micro-tomography (LTM) method to determine the permeability and entry pressure of two dimensional (2D) translucent porous media and integrates the LTM with a criterion of relative gradient error to quantify the corresponding REV of porous media. As a result, the DNAPL migration in porous media might be accurately simulated by discretizing the model at the REV dimension. To validate the quantification methods, an experiment of perchloroethylene (PCE) migration is conducted in a two-dimensional heterogeneous bench-scale aquifer cell. Based on the quantifications of permeability, entry pressure and REV scales of 2D porous media determined by the LTM and relative gradient error, different models with different sizes of discretization grid are used to simulate the PCE migration. It is shown that the model based on REV size agrees well with the experimental results over the entire migration period including calibration, verification and validation processes. This helps to better understand the microstructures of porous media and achieve accurately simulating DNAPL migration in aquifers based on the REV estimation.

  20. A SCREENING MODEL FOR SIMULATING DNAPL FLOW AND TRANSPORT IN POROUS MEDIA: THEORETICAL DEVELOPMENT

    EPA Science Inventory

    There exists a need for a simple tool that will allow us to analyze a DNAPL contamination scenario from free-product release to transport of soluble constituents to downgradient receptor wells. The objective of this manuscript is to present the conceptual model and formulate the ...

  1. A MODIFIED LIGHT TRANSMISSION VISUALIZATION METHOD FOR DNAPL SATURATION MEASUREMENTS IN 2-D MODELS

    EPA Science Inventory

    In this research, a light transmission visualization (LTV) method was used to quantify dense non-aqueous phase liquids (DNAPL) saturation in two-dimensional (2-D), two fluid phase systems. The method is an expansion of earlier LTV methods and takes into account both absorption an...

  2. EVALUATION OF TECHNOLOGIES FOR IN SITU CLEANUP OF DNAPL CONTAMINATED SITES

    EPA Science Inventory

    Ground-water contamination by nonaqueous phase liquids poses one of the greatest remedial challenges In the field of environmental engineering. Denser-than-water nonaqueous phase liquids (DNAPLs) are especially problematic due to their tow water solubility, high density, and capi...

  3. EVALUATION OF TECHNOLOGIES FOR IN SITU CLEANUP OF DNAPL CONTAMINATED SITES

    EPA Science Inventory

    Ground water contamination by non-aqueous phase liquids poses one of the greatest remedial challenges in the field of environmental engineering. Denser-than-water non-aqueous phase liquids (DNAPLs) are especially problematic due to their low water solubility, high density, an...

  4. FIELD EVALUATION OF THE TREATMENT OF DNAPL USING EMULSIFIED ZERO-VALENT IRON

    EPA Science Inventory

    A pilot scale field demonstration of dense non-aqueous phase liquids (DNAPL) treatment using emulsified zero-valent iron (EZVI) is being conducted at Parris Island Marine Corps Recruit Depot (MCRD), Parris Island SC. The demonstration is being conducted by Geosyntec, the Nationa...

  5. FIELD EVALUATION OF THE TREATMENT OF DNAPL USING EMULSIFIED ZERO-VALENT IRON (BATTELLE PRESENTATION)

    EPA Science Inventory

    A pilot scale field demonstration of dense non-aqueous phase liquids (DNAPL) treatment using emulsified zero-valent iron (EZVI) is being conducted at Parris Island Marine Corps Recruit Depot (MCRD), Parris Island SC. The EZVI technology was developed at the University of Central ...

  6. THE DNAPL REMEDIATION CHALLENGE: IS THERE A CASE FOR SOURCE DEPLETION?

    EPA Science Inventory

    Releases of Dense Non-Aqueous Phase Liquids (DNAPLs) at a large number of public and private sector sites in the United States pose significant challenges in site remediation and long-term site management. Extensive contamination of groundwater occurs as a result of significant ...

  7. Spatial And Temporal Distribution Of Microbial Communities In A TCE DNAPL Site: SABRE Field Studies

    EPA Science Inventory

    The SABRE (Source Area BioREmediation) project was conducted to evaluate accelerated anaerobic bioremediation of chlorinated solvents in areas of high concentration, such as DNAPL source areas. To study performance of this technology, a test cell was constructed with a longitudi...

  8. MONITOIRNG OF A CONTROLLED DNAPL SPILL USING A PROTOTYPE DIELECTRIC LOGGING TOOL

    EPA Science Inventory

    The U. S. Geological Survey (USGS) utilized their prototype dielectric logging tool to monitor a controlled Dense Non-Aqueous Phase Liquid (DNAPL) spill into a large tank located at the University of California Richmond Field Station (RFS) containing multiple sand and clayey sand...

  9. SERDP and ESTCP Expert Panel Workshop on Reducing the Uncertainty of DNAPL Source Zone Remediation

    DTIC Science & Technology

    2006-09-01

    permeability matrix blocks between fractures (Goldstein et al, 2004; O’Hara et al, 2000). In fractured sedimentary rock aquifers (sandstones, dolostones ...Remediation Parker, B.L., L.S. Burns, C.M. Turner, and J.A. Cherry. 2006. DNAPL Origin for Deep Herbicide and TCE Contamination in a Dolostone Aquifer

  10. Characterizing The Microbial Community In A TCE DNAPL Site: SABRE Column And Field Studies

    EPA Science Inventory

    The SABRE (Source Area BioREmediation) project is evaluating accelerated anaerobic bioremediation of chlorinated solvents in areas of high concentration, such as DNAPL source areas. In support of a field scale pilot test, column studies were conducted to design the system and ob...

  11. MONITOIRNG OF A CONTROLLED DNAPL SPILL USING A PROTOTYPE DIELECTRIC LOGGING TOOL

    EPA Science Inventory

    The U. S. Geological Survey (USGS) utilized their prototype dielectric logging tool to monitor a controlled Dense Non-Aqueous Phase Liquid (DNAPL) spill into a large tank located at the University of California Richmond Field Station (RFS) containing multiple sand and clayey sand...

  12. Transport, Targeting and Applications of Metallic Functional Nanoparticles for Degradation of DNAPL Chlorinated Organic Solvents

    SciTech Connect

    Lowry, Gregory V.; Majetich, Sara; Sholl, David; Tilton, Robert D.; Matyjaszewski, Krzysztof; Liu, Yueqiang; Sarbu, Traian; Almusallam, Abdulwahab; Redden, George D.; Meakin, Paul; Rollins, Harry W.

    2004-03-31

    Recently, laboratory and field studies have demonstrated that zero-valent iron nanoparticles (colloids) can rapidly transform dissolved chlorinated organic solvents into non-toxic compounds. This technology also has the potential to address Dense Non- Aqueous Phase Liquid (DNAPL) contamination, one of DOE's primary contamination problems. This project develops and tests polymer-modified reactive nanoscale Fe0 particles for in situ delivery to chlorinated solvents that are present as DNAPLs in the subsurface. The surfaces of reactive Fe0-based nanoparticles are modified with amphiphilic block copolymers to maintain a stable suspension of the particles in water for transport in a porous matrix and to create an affinity for the water-DNAPL interface. Ultimately this will provide an improved technology to locate and eliminate DNAPL, a recalcitrant and persistent source for groundwater contamination by chlorinated solvents. Candidate polymers have been synthesized and attached to 20 nm SiO2 particles using Atom Transfer Radical Polymerization (ATRP). The physical properties (hydrodynamic radius, stability, TCE-water partitioning behavior, mobility in a porous matrix) of these nanostructures have been determined. The particles (dp {approx}102 nm) are water soluble and partition to the TCE-water interface. The physical and chemical properties (e.g. oxide phase and thickness) of Fe0 nanoparticles synthesized using different techniques and the effects of these properties on particle reactivity and efficiency have been evaluated. Numerical models (Brownian Dynamics) have been developed to predict the aqueous diffusivities of these particle-polymer nanostructures.

  13. Radon as a Natural Partitioning Tracer for Locating and Quantifying DNAPL Saturation in the Subsurface

    NASA Astrophysics Data System (ADS)

    Davis, B. M.; Istok, J.; Semprini, L.

    2002-12-01

    The inability to locate and quantify dense nonaqueous phase liquid (DNAPL) saturation in the subsurface presents obstacles to site characterization and remediation. The objective of this study is to evaluate the use of naturally occurring radon as an in-situ, partitioning tracer to locate and quantify DNAPL saturation. In the saturated zone, radon emanating from aquifer solids occurs as a dissolved gas and, due to its non-polarity, partitions into DNAPL. Partitioning between the DNAPL and aqueous phases results in retarded radon transport during groundwater flow. The radon retardation factor can be determined using single-well 'push-pull' tracer tests, enabling the calculation of the DNAPL saturation. Radon can also be used as a 'static' partitioning tracer, whereby grab samples of radon from monitoring wells in contaminated and non-contaminated portions of an aquifer are collected and compared to calculate the DNAPL saturation and to monitor saturation changes as remediation proceeds. The utility of these methods was investigated in the laboratory using a physical aquifer model (PAM). Static and push-pull tests were performed before and after contamination of a portion of the PAM sediment pack with trichloroethene (TCE). The PAM was then remediated using alcohol cosolvent and tap water flushes, and static and push-pull tests were performed to assess the efficacy of remediation. Numerical simulations were used to estimate the retardation factor for radon in the push-pull tests. Radon partitioning was observed in static and push-pull tests conducted after TCE contamination. Calculated TCE saturations ranged up to 1.4 % (static test) and 14.1 % (push-pull test), based on the numerical method modeling approach used to analyze the results. Post-remediation tests showed decreases in TCE saturations. The results show that radon is sensitive to changes in DNAPL (e.g., TCE) saturation in space and time. Recent advances in numerical modeling of radon in push-pull tests have

  14. Bisphenol-A removal in various wastewater treatment processes: operational conditions, mass balance, and optimization.

    PubMed

    Guerra, P; Kim, M; Teslic, S; Alaee, M; Smyth, S A

    2015-04-01

    Bisphenol-A (BPA) was analyzed in 499 liquid and 347 solid samples collected from twenty-five wastewater treatment plants (WWTPs) to investigate parameters affecting BPA occurrence, removal, and fate. Lagoons, chemically-assisted primary treatment, secondary treatment, and advanced treatment processes were included. Median BPA concentrations in influent and final effluent were 400 ng/L and 150 ng/L, respectively. Median removal efficiencies ranged from 1 to 77%. Respective median BPA levels in primary sludge, secondary biological sludge, and biosolids were 230, 260, and 460 ng/g with digested biosolids having the highest concentrations. The biological aerated filter and membrane bioreactor processes showed the best performance, while chemically-assisted primary treatment achieved the lowest removal. Biodegradation and sorption contributing to BPA removal were influenced by operational conditions: hydraulic retention time (HRT), solids retention time (SRT), and mixed liquor suspended solids (MLSS). The influence of HRT, SRT, and MLSS in the bioreactor was stronger during cold temperatures. In order to achieve above 80% removal, the required conditions for HRT, SRT, and MLSS were 13 h, 7 days, and 1600 mg/L during summer (median temperature 19 °C) and 13 h, 17 days, and 5300 mg/L during winter (median temperature 10 °C); indicating that longer SRT and higher MLSS were needed during winter. BPA's sorption tendency to sludge was strongly influenced by the degree of nitrification and HRT.

  15. Transnasal, Endoscopically Guided Skull-Based Surgery by Pharyngotomy for Mass Removal from the Sphenopalatine Sinus in a Horse.

    PubMed

    Radcliffe, Rolfe M; Messiaen, Yasmine; Irby, Nita L; Divers, Thomas J; Dewey, Curtis W; Mitchell, Katharyn J; Schnabel, Lauren V; Bezuidenhout, Abraham J; Scrivani, Peter V; Ducharme, Norm G

    2016-11-01

    To report a transnasal, endoscopically guided ventral surgical approach for accessing the cranial and caudal segments of the sphenopalatine sinus for mass removal in a horse. Case report. Adult horse with acute onset blindness referable to a soft tissue mass within the sphenopalatine sinus. A 7-year-old Warmblood gelding presented with a history of running into a fence and falling. No neurologic signs were identified at initial examination but acute blindness was noted 3 weeks later. On computed tomography (CT) the sphenopalatine sinus was filled with a large homogeneous mass with poor contrast enhancement that extended dorsally with thinning to the dorsal cortex of the sphenoid bone, just rostral to the entrance of the optic canals into the cranial cavity. Surgical access to the sphenopalatine sinus was achieved using a transnasal, endoscopically guided ventral pharyngotomy approach and the mass lesion was removed. A presumptive diagnosis of chondroma was made based on histopathology. The horse recovered well from surgery, and although it has not regained vision as of 6.5 years postoperatively, the disease has not progressed. Transnasal, endoscopically-guided ventral surgical access to the sphenopalatine sinus is possible in horses and may improve access in horses with disease extending caudally beyond the palatine portion of the sinus. Use of smaller diameter or specialized instruments, such as various endoscopic bone cutting instruments, and CT image guidance may improve sinus access by this route. © Copyright 2016 by The American College of Veterinary Surgeons.

  16. Removing Biases in Resolved Stellar Mass Maps of Galaxy Disks through Successive Bayesian Marginalization

    NASA Astrophysics Data System (ADS)

    Martínez-García, Eric E.; González-Lópezlira, Rosa A.; Magris C., Gladis; Bruzual A., Gustavo

    2017-01-01

    Stellar masses of galaxies are frequently obtained by fitting stellar population synthesis models to galaxy photometry or spectra. The state of the art method resolves spatial structures within a galaxy to assess the total stellar mass content. In comparison to unresolved studies, resolved methods yield, on average, higher fractions of stellar mass for galaxies. In this work we improve the current method in order to mitigate a bias related to the resolved spatial distribution derived for the mass. The bias consists in an apparent filamentary mass distribution and a spatial coincidence between mass structures and dust lanes near spiral arms. The improved method is based on iterative Bayesian marginalization, through a new algorithm we have named Bayesian Successive Priors (BSP). We have applied BSP to M51 and to a pilot sample of 90 spiral galaxies from the Ohio State University Bright Spiral Galaxy Survey. By quantitatively comparing both methods, we find that the average fraction of stellar mass missed by unresolved studies is only half what previously thought. In contrast with the previous method, the output BSP mass maps bear a better resemblance to near-infrared images.

  17. Direct Push Optical Screening Tool for High-Resolution, Real-Time Mapping of Chlorinated Solvent DNAPL Architecture

    DTIC Science & Technology

    2016-04-01

    FINAL REPORT Direct Push Optical Screening Tool for High-Resolution, Real- Time Mapping of Chlorinated Solvent DNAPL Architecture ESTCP Project ER...Direct Push Optical Screening Tool for High Resolution, Real-time Mapping of Chlorinated Solvent DNAPL Architecture Murray Einarson Haley...for real-time, high-resolution mapping of petroleum hydrocarbon and coal tar-based NAPL source zones. The objective of this project is to demonstrate

  18. Direct Push Optical Screening Tool for High Resolution, Real-Time Mapping of Chlorinated Solvent DNAPL Architecture

    DTIC Science & Technology

    2016-07-01

    ER-201121) Direct Push Optical Screening Tool for High- Resolution, Real-Time Mapping of Chlorinated Solvent DNAPL Architecture July 2016 This...Report April 2011 - March 2016 Direct Push Optical Screening Tool for High Resolution, Real-time Mapping of Chlorinated Solvent DNAPL Architecture...tools are currently available for real-time, high-resolution mapping of petroleum hydrocarbon and coal tar-based NAPL source zones. The objective of

  19. Estimating the Extent and Thickness of DNAPL within the A/M Area of the Savannah River Site

    SciTech Connect

    Jackson, D.G.; Payne, T.H.; Looney, B.B.; Rossabi, J.

    1996-12-20

    The objective of this study is to refine the current conceptual model for the extent, character, and thickness of DNAPL contamination in the A/M Area. The evaluation is based upon historical records of operations and waste management and on detailed screening of historical groundwater concentrations against solubility limits. The topology of the Green Clay confining zone is used as the primary factor determining DNAPL pool thickness and resulting migration paths.

  20. Stochastical analysis of surfactant-enhanced remediation of denser-than-water nonaqueous phase liquid (DNAPL)-contaminated soils.

    PubMed

    Zhang, Renduo; Wood, A Lynn; Enfield, Carl G; Jeong, Seung-Woo

    2003-01-01

    Stochastical analysis was performed to assess the effect of soil spatial variability and heterogeneity on the recovery of denser-than-water nonaqueous phase liquids (DNAPL) during the process of surfactant-enhanced remediation. UTCHEM, a three-dimensional, multicomponent, multiphase, compositional model, was used to simulate water flow and chemical transport processes in heterogeneous soils. Soil spatial variability and heterogeneity were accounted for by considering the soil permeability as a spatial random variable and a geostatistical method was used to generate random distributions of the permeability. The randomly generated permeability fields were incorporated into UTCHEM to simulate DNAPL transport in heterogeneous media and stochastical analysis was conducted based on the simulated results. From the analysis, an exponential relationship between average DNAPL recovery and soil heterogeneity (defined as the standard deviation of log of permeability) was established with a coefficient of determination (r2) of 0.991, which indicated that DNAPL recovery decreased exponentially with increasing soil heterogeneity. Temporal and spatial distributions of relative saturations in the water phase, DNAPL, and microemulsion in heterogeneous soils were compared with those in homogeneous soils and related to soil heterogeneity. Cleanup time and uncertainty to determine DNAPL distributions in heterogeneous soils were also quantified. The study would provide useful information to design strategies for the characterization and remediation of nonaqueous phase liquid-contaminated soils with spatial variability and heterogeneity.

  1. Mobilization and entry of DNAPL pools into finer sand media by cosolvents: two-dimensional chamber studies.

    PubMed

    Van Valkenburg, Michael E; Annable, Michael D

    2002-12-01

    Two-dimensional chamber studies were conducted to determine qualitative and quantitative performance of cosolvents targeted at pooled dense non-aqueous phase liquid (DNAPL) (perchlorethylene, PCE) residing above a fine-grain capillary barrier. Downward mobilization of DNAPL, up gradient along an overriding cosolvent front, was observed. This produced significant pooling above a fine-grain layer that in some cases lead to entry into the capillary barrier beneath. Entry pressure calculations using physical and hydrogeologic parameters provided an excellent prediction of breakthrough of DNAPL into the capillary barrier. Calculations predict approximately 0.5 m of DNAPL would be necessary to enter a Beit Netofa clay, under extreme cosolvent flooding conditions (100% ethanol). Gradient injection of cosolvent did not appear to provide any benefit suggesting a rapid decrease in interfacial tension (IFT) compared to the rate of DNAPL solubilization. Use of a partitioning alcohol (tertiary butyl alcohol, TBA) resulted in DNAPL swelling and reduced entry into the capillary barrier. However, the trapping of flushing solution, containing PCE, could potentially lead to longer remediation times.

  2. Dissolved plume attenuation with DNAPL source remediation, aqueous decay and volatilization — Analytical solution, model calibration and prediction uncertainty

    NASA Astrophysics Data System (ADS)

    Parker, Jack C.; Park, Eungyu; Tang, Guoping

    2008-11-01

    A vertically-integrated analytical model for dissolved phase transport is described that considers a time-dependent DNAPL source based on the upscaled dissolution kinetics model of Parker and Park with extensions to consider time-dependent source zone biodecay, partial source mass reduction, and remediation-enhanced source dissolution kinetics. The model also considers spatial variability in aqueous plume decay, which is treated as the sum of aqueous biodecay and volatilization due to diffusive transport and barometric pumping through the unsaturated zone. The model is implemented in Excel/VBA coupled with (1) an inverse solution that utilizes prior information on model parameters and their uncertainty to condition the solution, and (2) an error analysis module that computes parameter covariances and total prediction uncertainty due to regression error and parameter uncertainty. A hypothetical case study is presented to evaluate the feasibility of calibrating the model from limited noisy field data. The results indicate that prediction uncertainty increases significantly over time following calibration, primarily due to propagation of parameter uncertainty. However, differences between the predicted performance of source zone partial mass reduction and the known true performance were reasonably small. Furthermore, a clear difference is observed between the predicted performance for the remedial action scenario versus that for a no-action scenario, which is consistent with the true system behavior. The results suggest that the model formulation can be effectively utilized to assess monitored natural attenuation and source remediation options if careful attention is given to model calibration and prediction uncertainty issues.

  3. Mass flow of antibiotics in a wastewater treatment plant focusing on removal variations due to operational parameters.

    PubMed

    Marx, Conrad; Günther, Norbert; Schubert, Sara; Oertel, Reinhard; Ahnert, Markus; Krebs, Peter; Kuehn, Volker

    2015-12-15

    Wastewater treatment plants (WWTPs) are not designed to purposefully eliminate antibiotics and therefore many previous investigations have been carried out to assess their fate in biological wastewater treatment processes. In order to consolidate previous findings regarding influencing factors like the solid and hydraulic retention time an intensive monitoring was carried out in a municipal WWTP in Germany. Over a period of 12months daily samples were taken from the in- and effluent as well as diverse sludge streams. The 14 selected antibiotics and one metabolite cover the following classes: cephalosporins, diaminopyrimidines, fluoroquinolones, lincosamide, macrolides, penicillins, sulfonamides and tetracyclines. Out of the 15 investigated substances, the removal of only clindamycin and ciprofloxacin show significant correlations to SRT, temperature, HRT and nitrogen removal. The dependency of clindamycin's removal could be related to the significant negative removal (i.e. production) of clindamycin in the treatment process and was corrected using the human metabolite clindamycin-sulfoxide. The average elimination was adjusted from -225% to 3% which suggests that clindamycin can be considered as an inert substance during the wastewater treatment process. Based on the presented data, the mass flow analysis revealed that macrolides, clindamycin/clindamycin-sulfoxide and trimethoprim were mainly released with the effluent, while penicillins, cephalosporins as well as sulfamethoxazole were partly degraded in the studied WWTP. Furthermore, levofloxacin and ciprofloxacin are the only antibiotics under investigation with a significant mass fraction bound to primary, excess and digested sludge. Nevertheless, the sludge concentrations are highly inconsistent which leads to questionable results. It remains unclear whether the inconsistencies are due to insufficiencies in sampling and/or analytical determination or if the fluctuations can be considered reasonable for

  4. The delineation of DNAPL in a heterogeneous unconsolidated aquifer using a hydro punch sampler and hydrophobic dye testing procedures

    SciTech Connect

    Cirilli, J.; DeRose, N.

    1995-09-01

    The site is a pharmaceutical facility located in Newark, New Jersey. The facility which has been in operation for approximately 90 years, previously contained a 15,000 gallon underground tank used to store TCE. Upon the tanks removal in the early 1980`s the tank integrity was found to have been compromised. In compliance with the NJDEP Industrial Site Recovery Act, the responsible party was required to locate DNAPL in the aquifer. Due to TCE`s relative density, vertical migration to depths greater than 80 feet has occurred. Lateral migration over distances greater than 500 feet has been documented. Currently, the investigation has focused on the neighboring cemetery, where approximately 20 deep soil borings have been advanced at selected locations downslope of the TCE source area. The soil borings were drilled by mud rotary methods to a depth that was determined in the field to be proximal to the bottom of the heterogeneous unconsolidated aquifer. Continuous split spoon soil sampling for detailed geologic interpretation and field screening utilizing an organic vapor instrument was performed. The Hydro Punch (HP II) sampler was used in the aqueous sampling model to collect a discrete ground water sample from the interface between the aquifer and the till.

  5. Prospective Pilot Investigation: Presurgical Depressive Symptom Severity and Anesthesia Response in Women Undergoing Surgery for Gynecologic Mass Removal

    PubMed Central

    Pereira, Deidre B.; Andre, Rachel; Garvan, Cynthia Wilson; Nguyen, Peter; Herman, Mary; Seubert, Christoph

    2014-01-01

    Background Anesthesia depth has been associated with mortality. The association between anesthesia depth and presurgery physical and health status, however, is currently debated. Depression is one comorbid condition that warrants investigation given its association to reduced frontal lobe activity and high prevalence in known surgery samples (e.g., gynecologic mass removal). Purpose This pilot study examined the hypothesis that severity of acute depressive symptoms would associate with greater sensitivity to anesthesia as measured by a frontal lobe electroencephalogram (EEG)-based monitor during the anesthesia induction phase among women undergoing gynecologic mass removal. Method This was a prospective and surgery anesthesia-controlled pilot investigation with 31 women undergoing surgery for removal of pelvic/gynecologic masses. Participants completed the Millon Behavioral Medicine Diagnostic (MBMD) inventory to assess depressive-related symptomatology. A Bispectral Index Score (BIS™) monitor (Aspect Medical Systems Inc., MA) was placed on the left frontal region to measure change in response from a set pre-anesthesia baseline point throughout the induction phase (6.5 min of the anesthetic). BIS™ change was calculated using a modified “area under the curve with respect to ground” formula. Results Greater sensitivity to anesthesia during induction was significantly associated with higher MBMD future pessimism scores and marginally associated with higher MBMD depression scores. Depressive personality, anxiety severity, tumor type, age, medication use, and comorbidity scores were not found to be predictors of BIS score change. Conclusion These pilot findings suggest that preoperative psychological health and anesthesia response are not independent. Acute presurgery depression and anesthesia response warrant closer empirical examination. PMID:25421878

  6. Apparatus for passive removal of subsurface contaminants and mass flow measurement

    DOEpatents

    Jackson, Dennis G.; Rossabi, Joseph; Riha, Brian D.

    2003-07-15

    A system for improving the Baroball valve and a method for retrofitting an existing Baroball valve. This invention improves upon the Baroball valve by reshaping the interior chamber of the valve to form a flow meter measuring chamber. The Baroball valve sealing mechanism acts as a rotameter bob for determining mass flow rate through the Baroball valve. A method for retrofitting a Baroball valve includes providing static pressure ports and connecting a measuring device, to these ports, for measuring the pressure differential between the Baroball chamber and the well. A standard curve of nominal device measurements allows the mass flow rate to be determined through the retrofitted Baroball valve.

  7. Displacement and sweep efficiencies in a DNAPL recovery test using micellar and polymer solutions injected in a five-spot pattern

    NASA Astrophysics Data System (ADS)

    Martel, Richard; Hébert, Alain; Lefebvre, René; Gélinas, Pierre; Gabriel, Uta

    2004-11-01

    Soil washing with micellar solutions is a promising alternative for the remediation of DNAPL source zones. As with any flushing technology, the success of soil washing with micellar solutions depends in a very large part on the ability of the solution to contact the contaminant (sweep efficiency) and then on the efficiency of contaminant removal once this contact is made (displacement efficiency). We report here on a field test where a micellar solution was used to recover a DNAPL in an open five-spot pattern in which polymer solutions were also injected before and after the washing solution to improve sweep efficiency. The washing solution formulation was optimised in the laboratory prior to the test to obtain good dissolution capacity. For a high-concentration and low-volume soil flushing remediation test such as the one performed (0.8 pore volumes of actual washing solution injected), slug sizing of the washing solution is critical. It was evaluated by an analytical solution. In a five-spot pattern, the displacement efficiency of the washing solution was observed to vary in the porous medium as a function of the radial distance from the injection well because: (1) the volume of the washing solution flowing through a section of the test cell changes (maximum close to the injection well and minimal at the pumping wells); (2) the in situ velocity changes (maximum at the wells and minimum between the wells) and; (3) the contact time of the washing solution with the NAPL changes as a function of the distance from the injection well. The relative importance of the recovery mechanisms, mobilisation and dissolution, was also observed to vary in the test cell. The reduced velocity increased the contact time of the washing solution with the DNAPL enhancing its dissolution, but the decrease of the capillary number caused less mobilisation. The washing process is much more extensive around the injection well. The use of an injection-pumping pattern allowing a complete sweep

  8. IN-SITU THERMAL TREATMENT SYSTEM PERFORMANCE AND MASS REMOVAL METRICS AT FORT LEWIS

    EPA Science Inventory

    The EGDY is the source of a potentially expanding three mile long TCE plume in a sole source drinking water aquifer. Thermal remediation is being employed to reduce source mass loading to the dissolved phase aquifer plume and reduce the time to reach site cleanup goals. This is...

  9. IN-SITU THERMAL TREATMENT SYSTEM PERFORMANCE AND MASS REMOVAL METRICS AT FORT LEWIS

    EPA Science Inventory

    The EGDY is the source of a potentially expanding three mile long TCE plume in a sole source drinking water aquifer. Thermal remediation is being employed to reduce source mass loading to the dissolved phase aquifer plume and reduce the time to reach site cleanup goals. This is...

  10. Investigation of surfactant-enhanced mass removal and flux reduction in 3D correlated permeability fields using magnetic resonance imaging.

    PubMed

    Zhang, Changyong; Werth, Charles J; Webb, Andrew G

    2008-09-10

    Magnetic resonance imaging (MRI) was used to visualize the NAPL source zone architecture before and after surfactant-enhanced NAPL dissolution in three-dimensional (3D) heterogeneously packed flowcells characterized by different longitudinal correlation lengths: 2.1 cm (aquifer 1) and 1.1 cm (aquifer 2). Surfactant flowpaths were determined by imaging the breakthrough of a paramagnetic tracer (MnCl(2)) analyzed by the method of moments. In both experimental aquifers, preferential flow occurred in high permeability materials with low NAPL saturations, and NAPL was preferentially removed from the top of the aquifers with low saturation. Alternate flushing with water and two surfactant pulses (5-6 pore volumes each) resulted in approximately 63% of NAPL mass removal from both aquifers. However, overall reduction in mass flux (Mass Flux 1) exiting the flowcell was lower in aquifer 2 (68%) than in aquifer 1 (81%), and local effluent concentrations were found to increase by as high as 120 times at local sampling ports from aquifer 2 after surfactant flushing. 3D MRI images of NAPL revealed that NAPL migrated downward and created additional NAPL source zones in previously uncontaminated areas at the bottom of the aquifers. The additional NAPL source zones were created in the direction transverse to flow in aquifer 2, which explains the higher mass flux relative to aquifer 1. Analysis using a total trapping number indicates that mobilization of NAPL trapped in the two coarsest sand fractions is possible when saturation is below 0.5 and 0.4, respectively. Results from this study highlight the potential impacts of porous media heterogeneity and NAPL source zone architecture on advanced in-situ flushing technologies.

  11. Experimental and numerical investigation of DNAPL infiltration and spreading in a 2-D sandbox by means of light transmission method

    NASA Astrophysics Data System (ADS)

    Zheng, F.; Shi, X.; Wu, J.; Gao, Y. W.

    2013-12-01

    Chlorinated solvents such as trichloroethene (TCE) and tetrachloroethene (PCE) are widespread groundwater contaminants often referred to as dense non-aqueous phase liquids (DNAPLs). Accuracy description of the spreading behavior and configuration for subsurface DNAPL migration is important, especially favourable for design effective remediation strategies. In this study, a 2-D experiment was conducted to investigate the infiltration behavior and spatial distribution of PCE in saturated porous media. Accusand 20/30 mesh sand (Unimin, Le Sueur, MN) was used as the background medium with two 70/80 and 60/70 mesh lenses embedded to simulate heterogeneous conditions. Dyed PCE of 100 ml was released into the flow cell at a constant rate of 2ml/min using a Harvard Apparatus syringe pump with a 50 ml glass syringe for two times, and 5 ml/min water was continuously injected through the inlet at the left side of the sandbox, while kept the same effluent rate at right side to create hydrodynamic condition. A light transmission (LT) system was used to record the migration of PCE and determine the saturation distribution of PCE in the sandbox experiment with a thermoelectrically air-cooled charged-coupled device (CCD) camera. All images were processed using MATLAB to calculate thickness-averaged PCE saturation for each pixel. Mass balance was checked through comparing injected known mounts of PCE with that calculated from LT analysis. Results showed that LT method is effective to delineate PCE migration pathways and quantify the saturation distribution. The relative errors of total PCE volumes calculated by LT analysis at different times were within 15% of the injected PCE volumes. The simulation are conducted using the multiphase modeling software T2VOC, which calibrated by the LT analysis results of three recorded time steps to fit with the complete spatial-temporal distribution of the PCE saturation. Model verification was then performed using the other eight recorded time

  12. Simultaneous sample preconcentration and matrix removal using field-flow fractionation coupled to inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Al-Ammar, Assad; Siripinyanond, Atitaya; Barnes, Ramon M.

    2001-10-01

    An on-channel sample preconcentration-matrix removal arrangement, based on coupling field-flow fractionation (FFF) to inductively coupled plasma mass spectrometry (ICP-MS), has been constructed for on-line sample pretreatment ICP-MS trace element determination. A commercial FFF system is modified to incorporate an on-channel preconcentration procedure allowing injection of up to 50 ml of sample, which could be preconcentrated by 50-1400 fold. A high molecular weight complexing agent added to the sample forms strong complexes with the measured trace analytes but not with the sample matrix. When the sample-complexing agent mixture is introduced to the FFF unit, the uncomplexed matrix element is removed by permeation through a membrane that separates the FFF sample compartment. The trace analytes remain in the FFF channel, because their high molecular weight complexes do not permeate through the membrane. Preconcentration and matrix elimination occur simultaneously. The matrix-free, preconcentrated sample is introduced directly to the ICP-MS nebulizer. The method was tested using 10-ml sample aliquots that contain As, Cd, Cu, Mo, Pb, Re, Sn, Te, Tl, Y, Zn and Zr analytes and 5000 mg l -1 Ca or Na matrices and ethylene imine polymer complexing agent. Copper and Re isotopic ratio values in reference standards also were determined after preconcentration and matrix element removal.

  13. Simulation modeling for nitrogen removal and experimental estimation of mass fractions of microbial groups in single-sludge system.

    PubMed

    Huang, J S; Tsai, C C; Chou, H H; Ting, W H

    2006-01-01

    Nitrification-denitrification in a single-sludge nitrogen removal system (SSNRS; with a sufficient carbon source for denitrification) was performed. With an increase in the mixed liquor recycle ratio (R(m)) from 1 to 2, the total nitrogen (TN) removal efficiency at a lower volumetric loading rate (VLR=0.21 NH(4)(+)-N m(-3) d(-1)) increased, but the TN removal efficiency at a higher VLR (0.35 kg NH(4)(+)-N m(-3) d(-1)) decreased. A kinetic model that accounts for the mass fractions of Nitrosomonas, Nitrobacter, nitrate reducer and nitrite reducer (f(n1), f(n2), f(dn1), and f(dn2)) in the SSNRS and an experimental approach for the estimation of the mass fractions of nitrogen-related microbial groups are also proposed. The estimated f(dn1) plus f(dn2) (0.65-0.83) was significantly larger than the f(n1) plus f(n2) (0.28-0.32); the f(n1) (0.21-0.26) was larger than the f(n2) (0.05-0.07); and the f(dn1) (0.32-0.45) varied slightly with the f(dn2) (0.33-0.38). At the lower VLR, the f(dn1) plus f(dn2) increased with increasing R(m); however at the higher VLR, the f(dn1) plus f(dn2) did not increase with increasing R(m). By using the kinetic model, the calculated residual NH(4)(+)-N and NO(2)(-)-N in the anoxic reactor and NO(2)(-)-N and NO(3)(-)-N in the aerobic reactor were in fairly good agreement with the experimental data; the calculated NO(3)(-)-N in the anoxic reactor was over-estimated and the calculated NH(4)(+)-N in the aerobic reactor was under-estimated.

  14. Modeling GPR data to interpret porosity and DNAPL saturations for calibration of a 3-D multiphase flow simulation

    USGS Publications Warehouse

    Sneddon, Kristen W.; Powers, Michael H.; Johnson, Raymond H.; Poeter, Eileen P.

    2002-01-01

    Dense nonaqueous phase liquids (DNAPLs) are a pervasive and persistent category of groundwater contamination. In an effort to better understand their unique subsurface behavior, a controlled and carefully monitored injection of PCE (perchloroethylene), a typical DNAPL, was performed in conjunction with the University of Waterloo at Canadian Forces Base Borden in 1991. Of the various geophysical methods used to monitor the migration of injected PCE, the U.S. Geological Survey collected 500-MHz ground penetrating radar (GPR) data. These data are used in determining calibration parameters for a multiphase flow simulation. GPR data were acquired over time on a fixed two-dimensional surficial grid as the DNAPL was injected into the subsurface. Emphasis is on the method of determining DNAPL saturation values from this time-lapse GPR data set. Interactive full-waveform GPR modeling of regularized field traces resolves relative dielectric permittivity versus depth profiles for pre-injection and later-time data. Modeled values are end members in recursive calculations of the Bruggeman-Hanai-Sen (BHS) mixing formula, yielding interpreted pre-injection porosity and post-injection DNAPL saturation values. The resulting interpreted physical properties of porosity and DNAPL saturation of the Borden test cell, defined on a grid spacing of 50 cm with 1-cm depth resolution, are used as observations for calibration of a 3-D multiphase flow simulation. Calculated values of DNAPL saturation in the subsurface at 14 and 22 hours after the start of injection, from both the GPR and the multiphase flow modeling, are interpolated volumetrically and presented for visual comparison.

  15. Refinement of the Kansas City Plant site conceptual model with respect to dense non-aqueous phase liquids (DNAPL)

    SciTech Connect

    Korte, N.E.; Hall, S.C.; Baker, J.L.

    1995-10-01

    This document presents a refinement of the site conceptual model with respect to dense non-aqueous phase liquid (DNAPL) at the US Department of Energy Kansas City Plant (KCP). This refinement was prompted by a review of the literature and the results of a limited study that was conducted to evaluate whether pools of DNAPL were present in contaminated locations at the KCP. The field study relied on the micropurge method of sample collection. This method has been demonstrated as a successful approach for obtaining discrete samples within a limited aquifer zone. Samples were collected at five locations across 5-ft well screens located at the base of the alluvial aquifer at the KCP. The hypothesis was that if pools of DNAPL were present, the dissolved concentration would increase with depth. Four wells with highly contaminated groundwater were selected for the test. Three of the wells were located in areas where DNAPL was suspected, and one where no DNAPL was believed to be present. The results demonstrated no discernible pattern with depth for the four wells tested. A review of the data in light of the available technical literature suggests that the fine-grained nature of the aquifer materials precludes the formation of pools. Instead, DNAPL is trapped as discontinuous ganglia that are probably widespread throughout the aquifer. The discontinuous nature of the DNAPL distribution prevents the collection of groundwater samples with concentrations approaching saturation. Furthermore, the results indicate that attempts to remediate the aquifer with conventional approaches will not result in restoration to pristine conditions because the tortuous groundwater flow paths will inhibit the efficiency of fluid-flow-based treatments.

  16. Material Property Estimation for Direct Detection of DNAPL using Integrated Ground-Penetrating Radar Velocity, Imaging and Attribute Analysis

    SciTech Connect

    Bradford, John; Smithson, Scott B.; Holbrook, Stephen

    2001-06-01

    The focus of our work is direct detection of DNAPLs, specifically chlorinated solvents, via material property estimation from surface ground-penetrating radar (GPR) data. We combine sophisticated GPR processing methodology with quantitative attribute analysis and material property estimation to determine the location and extent of residual and/or pooled DNAPL in both the vadose and saturated zones. An important byproduct of our research is state-of-the-art imaging which allows us to pinpoint attribute anomalies, characterize stratigraphy, identify fracture zones, and locate buried objects. Implementation and verification of these methodologies will be a significant advance in GPR research and in meeting DOE's need for reliable in-situ characterization of DNAPL contamination. Chlorinated solvents have much lower electric permittivity and conductivity than water. An electrical property contrast is induced when solvents displace water in the sediment column resulting in an anomalous GPR signature. To directly identify zones of DNAPL contamination, we focus on three aspects of reflected wave behavior--propagation velocity, frequency dependent attenuation, and amplitude variation with offset (AVO). Velocity analysis provides a direct estimate of electric permittivity, attenuation analysis provides a measure of conductivity, and AVO behavior is used to estimate the permittivity ratio at a reflecting boundary. Areas of anomalously low electric permittivity and conductivity are identified as potential DNAPL rich zones. Preliminary work illustrated significant potential for quantitative direct detection methodologies in identifying shallow DNAPL source zones. It is now necessary to verify these methodologies in a field setting. To this end, the project is field oriented and has three primary objectives: (1) Develop a suite of methodologies for direct detection of DNAPLs from surface GPR data (2) Controlled field verification at well characterized, contaminated sites (3

  17. Forearc Mass Removal and the Effects of Subduction Erosion off the Nicoya Peninsula of Costa Rica

    NASA Astrophysics Data System (ADS)

    Vannucchi, P.; Ranero, C. R.; Scholl, D. W.

    2001-12-01

    Since early-middle Miocene subduction erosion has been the dominant process controlling the tectonics off northern Costa Rica. Leg 170's Site 1042, located 7 km landward of the Middle America Trench (MAT), reached the acoustically defined Base Of Slope Sediment (BOSS) horizon at a depth of ~ 3900 mbsl and yielded a carbonate-cemented breccia, 16.5 myr-old, formed in a nearshore setting. The overlain Pleistocene to Miocene slope sequence shows a benthic foraminifera record implying the subsidence of the margin from the upper bathyal to the abyssal depth. The breccia rests unconformably above an older breccia composed of Nicoya basement rocks attesting that the coastal exposed basement of the Nicoya Peninsula extends seaward below Miocene and younger slope sediment to near the inner trench wall. Here a ~16.5 myr-old shoreline has subsided ~4 km, and that since this time at least 10-12 km of crustal thinning has occurred beneath the BOSS horizon implying that the trench axis has migrated landward at ~3 km/myr. Seismic images show that normal faulting is widespread across the overriding plate. However, measured extension by normal faulting can only account for a minor amount of the subsidence of the upper plate. Thus, removal of material by basal tectonic erosion has to be invoked to the explain the thinning and long term margin subsidence. Along this segment of the MAT the rate of crust removal approaches 35 km3/myr/km of trench. Basal erosion of older forearc material allows low concentrations of 10Be in the arc. The 10Be output in the arc increase toward Nicaragua where seismic data suggest lower rates of recent subduction erosion.

  18. Nitrogen removal in Myriophyllum aquaticum wetland microcosms for swine wastewater treatment: (15) N-labelled nitrogen mass balance analysis.

    PubMed

    Zhang, Shunan; Liu, Feng; Xiao, Runlin; He, Yang; Wu, Jinshui

    2017-01-01

    Ecological treatments are effective for treating agricultural wastewater. In this study, wetland microcosms vegetated with Myriophyllum aquaticum were designed for nitrogen (N) removal from two strengths of swine wastewater, and (15) N-labelled ammonium (NH4(+) -N) was added to evaluate the dominant NH4(+) -N removal pathway. The results showed that 98.8% of NH4(+) -N and 88.3% of TN (TN: 248.6 mg L(-1) ) were removed from low-strength swine wastewater (SW1) after an incubation of 21 days, with corresponding values for high-strength swine wastewater (SW2) being 99.2% of NH4(+) -N and 87.8% of TN (TN: 494.9 mg L(-1) ). Plant uptake and soil adsorption respectively accounted for 24.0% and 15.6% of the added (15) N. Meanwhile, above-ground tissues of M. aquaticum had significantly higher biomass and TN content than below-ground (P < 0.05). (15) N mass balance analysis indicated that gas losses contributed 52.0% to the added (15) N, but the N2 O flux constituted only 7.5% of total gas losses. The dynamics of NO3(-) -N and N2 O flux revealed that strong nitrification and denitrification occurred in M. aquaticum microcosms, which was a dominant N removal pathway. These findings demonstrated that M. aquaticum could feasibly be used to construct wetlands for high N-loaded animal wastewater treatment. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  19. The DNAPL Remediation Challenge: Is There a Case for Source Depletion?

    DTIC Science & Technology

    2003-12-01

    vendors, which adds to uncertainties of cost, risk of failure, and risk of bankruptcy by the vendor. An additional uncertainty at most sites is the...current default assumption is that DNAPL sites will require several decades to centuries of plume management with signifi cant cost and future uncertainty...required for regulatory compliance, long-term source-zone and plume containment has evolved into the generally recognized low-cost default strategy, but

  20. Development of a Protocol and a Screening Tool for Selection of DNAPL Source Area Remediation

    DTIC Science & Technology

    2012-02-01

    University, Kingston, Ontario 171 2.9 Thesis Wes~ M R (2009), Mathematical Modelling ofDNAPL Source Zone Remediation, Ph.D. thesis, 431 pp, Queen’s...determination of the kinetic rate law for the oxidation of perchloroethylene by potassium permanganate”, Chemosphere , 40, 1383-1388. Huang, K.-C... Chemosphere , 40 (12), 1383-1388. Huang, K.-C., Hoag, G. E., Chheda, P., Woody, B. A., and Dobbs, G. M. 2001, Oxidation of chlorinated ethenes by

  1. Reaction and Transport Processes Controlling In Situ Chemical Oxidation of DNAPLs

    DTIC Science & Technology

    2006-11-01

    Characterization Methods and Prediction Tools.” CORT3D was developed to simulate permanganate ISCO including oxidation chemistry, multiple rate- limited NOD...amount of research has been devoted to developing methods to estimate kLa from measurable system parameters, including pore size and DNAPL saturation... simulate a subsurface soil and ground water system provide an alternative and enable more complete control. Unfortunately, large-scale tank

  2. Development of a Protocol and a Screening Tool for Selection of DNAPL Source Area Remediation

    DTIC Science & Technology

    2012-05-01

    Geosyntec Consultants, Queen’s University , and the University of Edinburgh are not liable for misuse of the information contained in, or output by...the DNAPL TEST software. Moreover, NAVFAC ESC does not endorse Geosyntec Consultants, Queen’s University , the University of Edinburgh, nor any of...Consultants, Inc. 130 Research Lane Suite 2 Guelph , Ontario NIG-5G3 Phone: 519-822-2230 Fax: 519-822-3151 E-mail: dmajor@geosyntec.com Co-Principal

  3. Designing, Assessing, and Demonstrating Sustainable Bioaugmentation for Treatment of DNAPL Sources in Fractured Bedrock

    DTIC Science & Technology

    2017-01-27

    Yes Yes Site accessibility NA1 2 Yes Yes Yes 1 NA; Not Applicable 2 Likely treatment interval where DNAPL and water- bearing fractures are present...the depth to the first water- bearing zone encountered during drilling of wells at Sites 37, 120, and 133 ranged from 12 ft bgs in Well 396-MW02 to 420...infiltrates into the ground water- bearing bedrock fracture zones. Based on the report, two different water types are present at OUs 4 and 9. Group

  4. Analyzing Remediation Technologies for Department of Energy Sites contaminated with DNAPL Pollitants - Thesis

    SciTech Connect

    Anthony F. Paptyi, Captain, USAF

    1997-03-01

    A comprehensive literature review to investigate the following topics: * Decision analysis - with specific attention to geologic applications * Multiattribute Utility Theory (MAUT) The development of DA tools that will accommodate life cycle cost, time, stochastic performance measures, and decision maker preferences for selecting remediation or containment technology trains for DNAPL contaminated sites A thorough sensitivity analysis of the results of the WAG6 site specific analysis for a specified spill volume Conclusions regarding the model and the sensitivity analysis Recommendations for further research

  5. Mass of chlorinated volatile organic compounds removed by Pump-and-Treat, Naval Air Warfare Center, West Trenton, New Jersey, 1996-2010

    USGS Publications Warehouse

    Lacombe, Pierre J.

    2011-01-01

    Pump and Treat (P&T) remediation is the primary technique used to contain and remove trichloroethylene (TCE) and its degradation products cis 1-2,dichloroethylene (cDCE) and vinyl chloride (VC) from groundwater at the Naval Air Warfare Center (NAWC), West Trenton, NJ. Three methods were used to determine the masses of TCE, cDCE, and VC removed from groundwater by the P&T system since it became fully operational in 1996. Method 1, is based on the flow volume and concentrations of TCE, cDCE, and VC in groundwater that entered the P&T building as influent. Method 2 is based on withdrawal volume from each active recovery well and the concentrations of TCE, cDCE, and VC in the water samples from each well. Method 3 compares the maximum monthly amount of TCE, cDCE, and VC from Method 1 and Method 2. The greater of the two values is selected to represent the masses of TCE, cDCE and VC removed from groundwater each month. Previously published P&T monthly reports used Method 1 to determine the mass of TCE, cDCE, and VC removed. The reports state that 8,666 pounds (lbs) of TCE, 13,689 lbs of cDCE, and 2,455 lbs of VC were removed by the P&T system during 1996-2010. By using Method 2, the mass removed was determined to be 8,985 lbs of TCE, 17,801 lbs of cDCE, and 3,056 lbs of VC removed, and Method 3, resulted in 10,602 lbs of TCE, 21,029 lbs of cDCE, and 3,496 lbs of VC removed. To determine the mass of original TCE removed from groundwater, the individual masses of TCE, cDCE, and VC (determined using Methods 1, 2, and 3) were converted to numbers of moles, summed, and converted to pounds of original TCE. By using the molar conversion the mass of original TCE removed from groundwater by Methods 1, 2, and 3 was 32,381 lbs, 39,535 lbs, and 46,452 lbs, respectively, during 1996-2010. P&T monthly reports state that 24,805 lbs of summed TCE, cDCE, and VC were removed from groundwater. The simple summing method underestimates the mass of original TCE removed by the P&T system.

  6. Characterization Activities to Determine the Extent of DNAPL in the Vadose Zone at the A-014 Outfall of A/M Area

    SciTech Connect

    Jackson, D.G.

    2000-09-05

    The purpose of this investigation was to perform characterization activities necessary to confirm the presence and extent of DNAPL in the shallow vadose zone near the headwaters of the A-014 Outfall. Following the characterization, additional soil vapor extraction wells and vadose monitoring probes were installed to promote and monitor remediation activities in regions of identified DNAPL.

  7. Removing costs from the health care supply chain: lessons from mass retail.

    PubMed

    Agwunobi, John; London, Paul A

    2009-01-01

    Improved supply-chain management and high-volume purchasing have benefited other industries. This same approach could also reduce health care costs. Streamlining layers in the supply chain and using purchasing volume to reduce prices can save money and may improve care. Providing access to in-store health clinics and low-cost generic drugs are examples of how this approach is being tested by mass retailers. We examine lessons learned from these and similar initiatives and identify opportunities to cut the costs of generic and name-brand drugs, medical supplies, over-the-counter remedies, and vision care.

  8. A mechanism of basal spacing reduction in sodium smectitic clay materials in contact with DNAPL wastes.

    PubMed

    Ayral-Cinar, Derya; Otero-Diaz, Margarita; Demond, Avery H

    2016-09-01

    There has been concern regarding the possible attack of clays in aquitards, slurry walls and landfill liners by dense nonaqueous phase liquid (DNAPL) wastes, resulting in cracking. Despite the fact that a reduction in basal spacing in sodium smectitic clay materials has been linked to cracking, no plausible mechanism by which this reduction occurs in contact with waste DNAPLs has been formulated. To elucidate a mechanism, screening studies were conducted that showed that the combination of an anionic surfactant (AOT), a nonionic surfactant (TritonX-100) and a chlorinated solvent, tetrachloroethylene (PCE), could replicate the basal spacing reduction and cracking behavior of water-saturated bentonite caused by two waste DNAPLs obtained from the field. FTIR measurements of this system showed a displacement of the HOH bending band of water symptomatic of desiccation. Sorption measurements showed that the uptake of AOT by bentonite increased eight fold in the presence of TritonX-100 and PCE. The evidence presented here supports a mechanism of syneresis, involving the extraction of water from the interlayer space of the clay through the synergistic sorption of a nonionic and anionic surfactant mixture. It is speculated that the solvation of water in reverse micellar aggregates is the process driving the syneresis. Copyright © 2016. Published by Elsevier Ltd.

  9. Mixed region reactors for in situ treatment of DNAPL contaminated low permeability media

    SciTech Connect

    West, O.R.; Siegrist, R.L.

    1996-08-01

    Fine-textured soils and sediments contaminated by dense non-aqueous phase liquids (DNAPLs) present a significant environmental restoration challenge. An emerging approach to rapid in situ treatment within low permeability media involves the use of soil mixing to create mixed region reactors wherein biological or physical/chemical treatment processes can be employed. In cohesive soils, mixing breaks up the original soil structure and produces soil aggregates or clods separated by interaggregate void spaces. These void spaces create preferential flow paths for more efficient extraction of contaminants from the soil matrix or more rapid diffusion of treatment agents into the soil aggregates. This enhancement technology has been most successfully used with vapor stripping. However, other technologies can also be coupled with soil mixing including chemical degradation, biodegradation and solidification. The application of this technology to DNAPL-contaminated low permeability media appears promising but requires further experiments and models that can simulate the movement of DNAPLs in mixed regions. 11 refs., 6 figs.

  10. Multidimensional Investigation of Bedrock Heterogeneity/Unconformities at a DNAPL-Impacted Site.

    PubMed

    Steelman, Colby M; Meyer, Jessica R; Parker, Beth L

    2017-04-12

    Organic solvent (i.e., dense nonaqueous phase liquid, DNAPL) migration in the subsurface is known to be extremely sensitive to geologic heterogeneity. There is often a focus on heterogeneity that results from changing depositional conditions over short spatial scales. Similar or even more extreme spatial heterogeneity can result postdeposition due to erosional processes. This study applies a synergistic approach based on a combination of high-resolution lithologic logs of continuous cores, borehole geophysical logs, surface electrical resistivity, and seismic refraction tomography models to assess spatial heterogeneity in a shallow bedrock sequence subject to multiple unconformities and contaminated with a mixture of organic chemicals. The persistence of DNAPL in the source zone and an associated dissolved-phase plume led to variable impacts on formation resistivity across the study site. Seismic refraction in combination with electrical resistivity tomography improved interpretation of highly irregular erosional boundaries by delineating sharp lateral transitions in lithologic composition near the source zone and across the dissolved-phase plume. Electrical resistivity was effective at differentiating between clean and mud-rich sandstones and their unconformable contact with an underlying dolostone. Geophysical measurements revealed eroded dolostone mounds encased by a network of younger mud-rich sandstones channelized by clean semi-lithified sand, all of which was buried beneath variable glacial drift. Our synergistic multidimensional approach resulted in the development of a detailed three-dimensional shallow bedrock geospatial model, which has led to an improved understanding of DNAPL migration and contaminant plume heterogeneity.

  11. DEMONSTRATION OF PILOT-SCALE PREVAPORATION SYSTEMS FOR VOLATILE ORGANIC COMPOUND REMOVAL FROM A SURFACTANT ENHANCED AQUIFER REMEDIATION FLUID. I. SPIRAL WOUND MEMBRANE MODULES

    EPA Science Inventory

    During the summer of 1996, a pilot-scale demonstration of a surfactant enhanced aquifer remediation (SEAR) process for removal of dense non-aqueous phase liquids (DNAPLs) from soils was conducted at Hill Air Force Base in Layton, Utah. Five thousand gallons of the extracted DNAP...

  12. DEMONSTRATION OF PILOT-SCALE PREVAPORATION SYSTEMS FOR VOLATILE ORGANIC COMPOUND REMOVAL FROM A SURFACTANT ENHANCED AQUIFER REMEDIATION FLUID. I. SPIRAL WOUND MEMBRANE MODULES

    EPA Science Inventory

    During the summer of 1996, a pilot-scale demonstration of a surfactant enhanced aquifer remediation (SEAR) process for removal of dense non-aqueous phase liquids (DNAPLs) from soils was conducted at Hill Air Force Base in Layton, Utah. Five thousand gallons of the extracted DNAP...

  13. The transport behaviour of elemental mercury DNAPL in saturated porous media: analysis of field observations and two-phase flow modelling.

    PubMed

    Sweijen, Thomas; Hartog, Niels; Marsman, Annemieke; Keijzer, Thomas J S

    2014-06-01

    Mercury is a contaminant of global concern. The use of elemental mercury in various (former) industrial processes, such as chlorine production at chlor-alkali plants, is known to have resulted in soil and groundwater contaminations worldwide. However, the subsurface transport behaviour of elemental mercury as an immiscible dense non-aqueous phase liquid (DNAPL) in porous media has received minimal attention to date. Even though, such insight would aid in the remediation effort of mercury contaminated sites. Therefore, in this study a detailed field characterization of elemental mercury DNAPL distribution with depth was performed together with two-phase flow modelling, using STOMP. This is to evaluate the dynamics of mercury DNAPL migration and the controls on its distribution in saturated porous media. Using a CPT-probe mounted with a digital camera, in-situ mercury DNAPL depth distribution was obtained at a former chlor-alkali-plant, down to 9 m below ground surface. Images revealing the presence of silvery mercury DNAPL droplets were used to quantify its distribution, characteristics and saturation, using an image analysis method. These field-observations with depth were compared with results from a one-dimensional two-phase flow model simulation for the same transect. Considering the limitations of this approach, simulations reasonably reflected the variability and range of the mercury DNAPL distribution. To further explore the impact of mercury's physical properties in comparison with more common DNAPLs, the migration of mercury and PCE DNAPL in several typical hydrological scenarios was simulated. Comparison of the simulations suggest that mercury's higher density is the overall controlling factor in controlling its penetration in saturated porous media, despite its higher resistance to flow due to its higher viscosity. Based on these results the hazard of spilled mercury DNAPL to cause deep contamination of groundwater systems seems larger than for any other

  14. The transport behaviour of elemental mercury DNAPL in saturated porous media: Analysis of field observations and two-phase flow modelling

    NASA Astrophysics Data System (ADS)

    Sweijen, Thomas; Hartog, Niels; Marsman, Annemieke; Keijzer, Thomas J. S.

    2014-06-01

    Mercury is a contaminant of global concern. The use of elemental mercury in various (former) industrial processes, such as chlorine production at chlor-alkali plants, is known to have resulted in soil and groundwater contaminations worldwide. However, the subsurface transport behaviour of elemental mercury as an immiscible dense non-aqueous phase liquid (DNAPL) in porous media has received minimal attention to date. Even though, such insight would aid in the remediation effort of mercury contaminated sites. Therefore, in this study a detailed field characterization of elemental mercury DNAPL distribution with depth was performed together with two-phase flow modelling, using STOMP. This is to evaluate the dynamics of mercury DNAPL migration and the controls on its distribution in saturated porous media. Using a CPT-probe mounted with a digital camera, in-situ mercury DNAPL depth distribution was obtained at a former chlor-alkali-plant, down to 9 m below ground surface. Images revealing the presence of silvery mercury DNAPL droplets were used to quantify its distribution, characteristics and saturation, using an image analysis method. These field-observations with depth were compared with results from a one-dimensional two-phase flow model simulation for the same transect. Considering the limitations of this approach, simulations reasonably reflected the variability and range of the mercury DNAPL distribution. To further explore the impact of mercury's physical properties in comparison with more common DNAPLs, the migration of mercury and PCE DNAPL in several typical hydrological scenarios was simulated. Comparison of the simulations suggest that mercury's higher density is the overall controlling factor in controlling its penetration in saturated porous media, despite its higher resistance to flow due to its higher viscosity. Based on these results the hazard of spilled mercury DNAPL to cause deep contamination of groundwater systems seems larger than for any other

  15. Impact of nonaqueous phase liquid (NAPL) source zone architecture on mass removal mechanisms in strongly layered heterogeneous porous media during soil vapor extraction.

    PubMed

    Yoon, Hongkyu; Werth, Charles J; Valocchi, Albert J; Oostrom, Mart

    2008-08-20

    An existing multiphase flow simulator was modified in order to determine the effects of four mechanisms on NAPL mass removal in a strongly layered heterogeneous vadose zone during soil vapor extraction (SVE): a) NAPL flow, b) diffusion and dispersion from low permeability zones, c) slow desorption from sediment grains, and d) rate-limited dissolution of trapped NAPL. The impacts of water and NAPL saturation distribution, NAPL-type (i.e., free, residual, or trapped) distribution, and spatial heterogeneity of the permeability field on these mechanisms were evaluated. Two different initial source zone architectures (one with and one without trapped NAPL) were considered and these architectures were used to evaluate seven different SVE scenarios. For all runs, slow diffusion from low permeability zones that gas flow bypassed was a dominant factor for diminished SVE effectiveness at later times. This effect was more significant at high water saturation due to the decrease of gas-phase relative permeability. Transverse dispersion contributed to fast NAPL mass removal from the low permeability layer in both source zone architectures, but longitudinal dispersion did not affect overall mass removal time. Both slow desorption from sediment grains and rate-limited mass transfer from trapped NAPL only marginally affected removal times. However, mass transfer from trapped NAPL did affect mass removal at later time, as well as the NAPL distribution. NAPL flow from low to high permeability zones contributed to faster mass removal from the low permeability layer, and this effect increased when water infiltration was eliminated. These simulations indicate that if trapped NAPL exists in heterogeneous porous media, mass transfer can be improved by delivering gas directly to zones with trapped NAPL and by lowering the water content, which increases the gas relative permeability and changes trapped NAPL to free NAPL.

  16. Impact of nonaqueous phase liquid (NAPL) source zone architecture on mass removal mechanisms in strongly layered heterogeneous porous media during soil vapor extraction

    SciTech Connect

    Yoon, Hongkyu; Werth, Charlie; Valocchi, Albert J.; Oostrom, Martinus

    2008-09-26

    An existing multiphase flow simulator was modified in order to determine the effects of four mechanisms on NAPL mass removal in a strongly layered heterogeneous vadose zone during soil vapor extraction (SVE): a) NAPL flow, b) diffusion and dispersion from low permeability zones, c) slow desorption from sediment grains, and d) rate-limited dissolution of trapped NAPL. The impact of water and NAPL saturation distribution, NAPL type (i.e., free, residual, or trapped) distribution, and spatial heterogeneity of the permeability field on these mechanisms were evaluated. Two different initial source zone architectures (one with and one without trapped NAPL) were considered and these architectures were used to evaluate seven different SVE scenarios. For all runs, slow diffusion from low permeability zones that gas flow bypassed was a dominant factor for diminished SVE effectiveness at later times. This effect was more significant at high water saturation due to the decrease of gas-phase relative permeability. Transverse dispersion contributed to fast NAPL mass removal from the low permeability layer in both source zone architectures, but longitudinal dispersion did not affect overall mass removal time. Both slow desorption from sediment grains and rate-limited mass transfer from trapped NAPL only marginally affected removal times. However, mass transfer from trapped NAPL did affect mass removal at late time, as well as the NAPL distribution. NAPL flow from low to high permeability zones contributed to faster mass removal from the low permeability layer, and this effect increased when water infiltration was eliminated. These simulations indicate that if trapped NAPL exists in heterogeneous porous media, mass transfer can be improved by delivering gas directly to zones with trapped NAPL and by lowering the water content, which increases the gas relative permeability and changes trapped NAPL to free NAPL.

  17. Herbivores alter plant-wind interactions by acting as a point mass on leaves and by removing leaf tissue.

    PubMed

    Kothari, Adit R; Burnett, Nicholas P

    2017-09-01

    In nature, plants regularly interact with herbivores and with wind. Herbivores can wound and alter the structure of plants, whereas wind can exert aerodynamic forces that cause the plants to flutter or sway. While herbivory has many negative consequences for plants, fluttering in wind can be beneficial for plants by facilitating gas exchange and loss of excess heat. Little is known about how herbivores affect plant motion in wind. We tested how the mass of an herbivore resting on a broad leaf of the tulip tree Liriodendron tulipifera, and the damage caused by herbivores, affected the motion of the leaf in wind. For this, we placed mimics of herbivores on the leaves, varying each herbivore's mass or position, and used high-speed video to measure how the herbivore mimics affected leaf movement and reconfiguration at two wind speeds inside a laboratory wind tunnel. In a similar setup, we tested how naturally occurring herbivore damage on the leaves affected leaf movement and reconfiguration. We found that the mass of an herbivore resting on a leaf can change that leaf's orientation relative to the wind and interfere with the ability of the leaf to reconfigure into a smaller, more streamlined shape. A large herbivore load slowed the leaf's fluttering frequency, while naturally occurring damage from herbivores increased the leaf's fluttering frequency. We conclude that herbivores can alter the physical interactions between wind and plants by two methods: (1) acting as a point mass on the plant while it is feeding and (2) removing tissue from the plant. Altering a plant's interaction with wind can have physical and physiological consequences for the plant. Thus, future studies of plants in nature should consider the effect of herbivory on plant-wind interactions, and vice versa.

  18. Removal of Endobronchial Malignant Mass by Cryotherapy Improved Performance Status to Receive Chemotherapy

    PubMed Central

    Hsieh, Meng-Heng; Wang, Tsai-Yu; Yu, Chih-Teng; Chou, Chun-Liang; Lin, Shu-Min; Kuo, Chih-Hsi; Chung, Fu-Tsai

    2014-01-01

    Although malignant endobronchial mass (MEM) has poor prognosis, cryotherapy is reportedly a palliative treatment. Clinical data on postcryotherapy MEM patients in a university-affiliated hospital between 2007 and 2011 were evaluated. Survival curve with or without postcryotherapy chemotherapy and performance status (PS) improvement of these subjects were analyzed using the Kaplan-Meier method. There were 59 patients (42 males), with median age of 64 years (range, 51–76, and median performance status of 2 (interquartile range [IQR], 2-3). Postcryotherapy complications included minor bleeding (n = 12) and need for multiple procedures (n = 10), while outcomes were relief of symptoms (n = 51), improved PS (n = 45), and ability to receive chemotherapy (n = 40). The survival of patients with chemotherapy postcryotherapy was longer than that of patients without such chemotherapy (median, 534 versus 106 days; log-rank test, P = 0.007; hazard ratio, 0.25; 95% confidence interval, 0.10–0.69). The survival of patients with PS improvement postcryotherapy was longer than that of patients without PS improvement (median, 406 versus 106 days; log-rank test, P = 0.02; hazard ratio, 0.28; 95% confidence interval, 0.10–0.81). Cryotherapy is a feasible treatment for MEM. With better PS after cryotherapy, further chemotherapy becomes possible for patients to improve survival when MEM caused dyspnea and poor PS. PMID:25383370

  19. Normalization Approaches for Removing Systematic Biases Associated with Mass Spectrometry and Label-Free Proteomics

    SciTech Connect

    Callister, Stephen J.; Barry, Richard C.; Adkins, Joshua N.; Johnson, Ethan T.; Qian, Weijun; Webb-Robertson, Bobbie-Jo M.; Smith, Richard D.; Lipton, Mary S.

    2006-02-01

    Central tendency, linear regression, locally weighted regression, and quantile techniques were investigated for normalization of peptide abundance measurements obtained from high-throughput liquid chromatography-Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR MS). Arbitrary abundances of peptides were obtained from three sample sets, including a standard protein sample, two Deinococcus radiodurans samples taken from different growth phases, and two mouse striatum samples from control and methamphetamine-stressed mice (strain C57BL/6). The selected normalization techniques were evaluated in both the absence and presence of biological variability by estimating extraneous variability prior to and following normalization. Prior to normalization, replicate runs from each sample set were observed to be statistically different, while following normalization replicate runs were no longer statistically different. Although all techniques reduced systematic bias, assigned ranks among the techniques revealed significant trends. For most LC-FTICR MS analyses, linear regression normalization ranked either first or second among the four techniques, suggesting that this technique was more generally suitable for reducing systematic biases.

  20. A Steady-State Mass Transfer Model of Removing CPAs from Cryopreserved Blood with Hollow Fiber Modules

    PubMed Central

    Ding, Weiping; Zhou, Xiaoming; Heimfeld, Shelly; Reems, Jo-Anna; Gao, Dayong

    2010-01-01

    Hollow fiber modules are commonly used to conveniently and efficiently remove cryoprotective agents (CPAs) from cryopreserved cell suspensions. In this paper, a steady-state model coupling mass transfers across cell and hollow fiber membranes is theoretically developed to evaluate the removal of CPAs from cryopreserved blood using hollow fiber modules. This steady-state model complements the unsteady-state model which was presented in our previous study. As the steady-state model, unlike the unsteady-state model, can be used to evaluate the effect of ultrafiltration flow rates on the clearance of CPAs. The steady-state model is validated by experimental results and then is compared with the unsteady-state model. Using the steady-state model, the effects of ultrafiltration flow rates, NaCl concentrations in dialysate, blood flow rates and dialysate flow rates on CPA concentration variation and cell volume response are investigated in detail. According to the simulative results, the osmotic damage of red blood cells (RBCs) can easily be reduced by increasing ultrafiltration flow rates, increasing NaCl concentrations in dialysate, increasing blood flow rates or decreasing dialysate flow rates. PMID:20524740

  1. Dense Non Aqueous Phase Liquid (DNAPL) Removal from Fractured Rock using Thermal Conductive Heating (TCH)

    DTIC Science & Technology

    2013-01-01

    or karst . As control of water inflow may be problematic in fractured media and karst , and capture of contaminants may be difficult, effectiveness is...fractured media and karst , and capture of contaminants may be difficult, effectiveness is expected to be limited in these settings. If water inflow...conductive heating below the water table… As control of water inflow may be problematic in fractured media and karst , and capture of contaminants may be

  2. Numerical modeling analysis of hydrodynamic and microbial controls on DNAPL pool dissolution and detoxification: Dehalorespirers in co-culture

    NASA Astrophysics Data System (ADS)

    Wesseldyke, Eric S.; Becker, Jennifer G.; Seagren, Eric A.; Mayer, Alex S.; Zhang, Changyong

    2015-04-01

    Dissolution of dense non-aqueous phase liquid (DNAPL) contaminants like tetrachloroethene (PCE) can be "bioenhanced" via biodegradation, which increases the concentration gradient at the DNAPL-water interface. Model simulations were used to evaluate the impact of ecological interactions between different dehalorespiring strains and hydrodynamics on the bioenhancement effect and the extent of PCE dechlorination. Simulations were performed using a two-dimensional coupled flow-transport model, with a DNAPL pool source and two microbial species, Dehalococcoides mccartyi 195 and Desulfuromonas michiganensis, which compete for electron acceptors (e.g., PCE), but not for their electron donors. Under biostimulation, low vx conditions, D. michiganensis alone significantly enhanced dissolution by rapidly utilizing aqueous-phase PCE. In co-culture under these conditions, D. mccartyi 195 increased this bioenhancement modestly and greatly increased the extent of PCE transformation. Although D. michiganensis was the dominant population under low velocity conditions, D. mccartyi 195 dominated under high velocity conditions due to bioclogging effects.

  3. Carbon mass balance and microbial ecology in a laboratory scale reactor achieving simultaneous sludge reduction and nutrient removal.

    PubMed

    Huang, Pei; Li, Liang; Kotay, Shireen Meher; Goel, Ramesh

    2014-04-15

    Solids reduction in activated sludge processes (ASP) at source using process manipulation has been researched widely over the last two-decades. However, the absence of nutrient removal component, lack of understanding on the organic carbon, and limited information on key microbial community in solids minimizing ASP preclude the widespread acceptance of sludge minimizing processes. In this manuscript, we report simultaneous solids reduction through anaerobiosis along with nitrogen and phosphorus removals. The manuscript also reports carbon mass balance using stable isotope of carbon, microbial ecology of nitrifiers and polyphosphate accumulating organisms (PAOs). Two laboratory scale reactors were operated in anaerobic-aerobic-anoxic (A(2)O) mode. One reactor was run in the standard mode (hereafter called the control-SBR) simulating conventional A(2)O type of activated sludge process and the second reactor was run in the sludge minimizing mode (called the modified-SBR). Unlike other research efforts where the sludge minimizing reactor was maintained at nearly infinite solids retention time (SRT). To sustain the efficient nutrient removal, the modified-SBR in this research was operated at a very small solids yield rather than at infinite SRT. Both reactors showed consistent NH3-N, phosphorus and COD removals over a period of 263 days. Both reactors also showed active denitrification during the anoxic phase even if there was no organic carbon source available during this phase, suggesting the presence of denitrifying PAOs (DNPAOs). The observed solids yield in the modified-SBR was 60% less than the observed solids yield in the control-SBR. Specific oxygen uptake rate (SOUR) for the modified-SBR was almost 44% more than the control-SBR under identical feeding conditions, but was nearly the same for both reactors under fasting conditions. The modified-SBR showed greater diversity of ammonia oxidizing bacteria and PAOs compared to the control-SBR. The diversity of PAOs

  4. Final Laboratory Treatabilty Report for: Emulsified Zero Valent Iron Treatment of Chlorinated Solvent DNAPL Source Areas. Revision 1.0

    DTIC Science & Technology

    2006-01-23

    do not reduce the clean - up time for sites where DNAPL is present. Nano-scale ZVI particles (nZVI), either in a water slurry or as particles...As a result of their high reactivity, nano-scale particles containing ZVI are quickly surrounded by a passivating layer – such as a shell of oxide ...occur. The rapid degradation of dissolved phase TCE by the fast-reacting nZVI may however enhance the dissolution of the DNAPL and reduce the clean

  5. Sampling results, DNAPL monitoring well GW-727, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. Quarterly report, 1995

    SciTech Connect

    1996-05-01

    In January 1990, dense, non aqueous phase liquids (DNAPLs) were discovered at a depth of approximately 274 feet below ground surface along the southern border of the Y-12 Plant Burial Grounds. Immediately after the discovery, an investigation was conducted to assess the occurrence of DNAPL at the site and to make recommendations for further action. A major task in the work plan calls for the construction and installation of five multiport wells. This report summarizes purging and sampling activities for one of these multiport wells, GW-727, and presents analytical results for GW- 727. This report summarizes purging and sampling activities for GW-727 and presents analytical results for GW-727.

  6. Material Property Estimation for Direct Detection of DNAPL using Integrated Ground-Penetrating Radar Velocity, Imaging and Attribute Analysis

    SciTech Connect

    Bradford, John H.; Holbrook, W. Stephen; Smithson, Scott B.

    2004-12-31

    The focus of this project is direct detection of DNAPLs, specifically chlorinated solvents, via material property estimation from multi-fold surface ground-penetrating radar (GPR) data. We combine state-of-the-art GPR processing methodology with quantitative attribute analysis and material property estimation to determine the location and extent of residual and/or pooled DNAPL in both the vadose and saturated zones. An important byproduct of our research is state-of-the-art imaging which allows us to pinpoint attribute anomalies, characterize stratigraphy, identify fracture zones, and locate buried objects.

  7. Material Property Estimation for Direct Detection of DNAPL using Integrated Ground-Penetrating Radar Velocity, Imaging and Attribute Analysis

    SciTech Connect

    John H. Bradford; Stephen Holbrook; Scott B. Smithson

    2004-12-09

    The focus of this project is direct detection of DNAPL's specifically chlorinated solvents, via material property estimation from multi-fold surface ground-penetrating radar (GPR) data. We combine state-of-the-art GPR processing methodology with quantitative attribute analysis and material property estimation to determine the location and extent of residual and/or pooled DNAPL in both the vadose and saturated zones. An important byproduct of our research is state-of-the-art imaging which allows us to pinpoint attribute anomalies, characterize stratigraphy, identify fracture zones, and locate buried objects.

  8. Extension and field application of an integrated DNAPL source identification algorithm that utilizes stochastic modeling and a Kalman filter

    NASA Astrophysics Data System (ADS)

    Dokou, Zoi; Pinder, George F.

    2011-02-01

    SummaryThe design of an effective groundwater remediation system involves the determination of the source zone characteristics and subsequent source zone removal. The work presented in this paper focuses on the three-dimensional extension and field application of a previously described source zone identification and delineation algorithm. The three-dimensional search algorithm defines how to achieve an acceptable level of accuracy regarding the strength, geographic location and depth of a dense non-aqueous phase liquid (DNAPL) source while using the least possible number of water quality samples. Target locations and depths of potential sources are identified and given initial importance measures or weights using a technique that exploits expert knowledge. The weights reflect the expert's confidence that the particular source location is the correct one and they are updated as the investigation proceeds. The overall strategy uses stochastic groundwater flow and transport modeling assuming that hydraulic conductivity is known with uncertainty (Monte Carlo approach). Optimal water quality samples are selected according to the degree to which they contribute to the total concentration uncertainty reduction across all model layers and the proximity of the samples to the potential source locations. After a sample is taken, the contaminant concentration plume is updated using a Kalman filter. The set of optimal source strengths is determined using linear programming by minimizing the sum of the absolute differences between modeled and measured concentration values at sampling locations. The Monte Carlo generated suite of plumes emanating from each individual source is calculated and compared with the updated plume. The scores obtained from this comparison serve to update the weights initially assigned by the expert, and the above steps are repeated until the optimal source characteristics are determined. The algorithm's effectiveness is demonstrated by performing a

  9. Determination of trace impurities in high purity gold by inductively coupled plasma mass spectrometry with prior matrix removal by electrodeposition

    NASA Astrophysics Data System (ADS)

    Sun, Y. C.; Hsieh, C. H.; Lin, T. S.; Wen, J. C.

    2000-09-01

    A novel method for the determination of 11 trace impurities (Be, Mg, Cr, Mn, Ni, Cu, Zn, Ag, Pd, Sn and Pb) in high purity gold with a combination of electrochemical deposition separation and inductively coupled plasma mass spectrometric measurement was investigated. In the present study, an efficient separation procedure was developed to remove the gold matrix by the electrodepositon method on the basis of the difference in reduction potential of gold and the other trace impurities. The effects of deposition potential, deposition time and composition of the electrolyte on the separation efficiency were studied. According to our experimental results, most impurities, except for silver, can remain in the electrolyte and the interference from gold can be completely removed through the application of electrodeposition at suitable potential. To achieve simultaneous separation of silver from the gold matrix, a unique complexation reaction between silver ions and ammonia ions was successfully employed to alter the reduction potential of silver ion. By way of a suitable adjustment of the deposition potential and the composition of electrolytes, the spike recoveries of 11 interesting impurities were found to be in the range of 85-105%. The limit of detection (based on the 3-σ criterion) of these elements was 10 -1-10 -2 μg g -1. The applicability of the proposed method has also been validated by the analysis of high purity gold reference materials (FAU9 and FAU11, Royal Canadian Mint). Comparing with the certified values, the recoveries of interesting elements were found to be in the range of 82-118% through the use of proposed method.

  10. A miniaturised electron ionisation time-of-flight mass spectrometer that uses a unique helium ion removal pulsing technique specifically for gas analysis.

    PubMed

    Qing, Jiang; Huang, Zhengxu; Zhang, Yan; Zhu, Hui; Tan, Guobin; Gao, Wei; Yang, Peng-yuan

    2013-06-21

    A miniaturised reflectron time-of-flight mass spectrometer combined with an electron ionisation ion source has been developed for the analysis of gases. An entirely new helium ion removal pulsing technique in this mass spectrometer is used to achieve an improved performance for the first time. The helium carrier gas, which enters into the source along with the gaseous sample, is simultaneously ionised and then orthogonally introduced into the time-of-fight mass analyser. Once the relatively light helium ions in the ion packet become extremely close to the reflectron plate (B-plate for short in this article), a modulated pulse is instantaneously applied on the B-plate and a negative reflectron voltage is set to the B-plate and lasts for a very short period, during which all the helium ions are directly bumped into the B-plate and subsequently removed. The helium ion removal pulsing technique can efficiently avoid saturation of the micro-channel plate caused by too many helium ions. A compact and durable instrument is designed, which has a mass resolving resolution greater than 400 FWHM for online gas analysis. The technology may also be further developed to remove other ions for TOF mass spectrometry.

  11. 3D Self-Potential Inversion for Monitoring DNAPL Contaminant Distributions

    NASA Astrophysics Data System (ADS)

    Minsley, B. J.; Sogade, J.; Vichabian, Y.; Morgan, F. D.

    2005-05-01

    Self-potential (SP) data are collected over an area known to be contaminated with Dense Non-Aqueous Phase Liquids (DNAPLs) at the Savannah River Site in South Carolina. The field experiment consists of approximately 100 SP measurements on a surface grid and in four boreholes, and is repeated after one year. DNAPLs are known to undergo redox reactions during their degradation in the environment, which is often biologically mediated. Self-potential geophysics is employed in this study because of its sensitivity to the in-situ biochemical processes that degrade the contaminants. These reactions provide an electrochemical source that is manifested as an SP signature at the measurement locations remote from the contaminated areas. 3D inversion of the SP data is therefore needed to spatially locate the distribution of sources, which is related to contaminant presence. The inversion incorporates the 3D resistivity structure collected at the same site, and is better constrained in depth by using borehole data and regularization. Ground truth information taken after the first field experiment provides concentration data with depth for several DNAPL species in five boreholes. There is a good correlation between the ground truth data and SP source inversion, though this comparison is limited by several factors: the difference in resolution of the ground truth and inverted data, and the dependence of the redox processes on other constituents that were not measured during the ground truthing, such as oxygen content or microbial presence. Inversion of the second year's dataset provides information on the changes in the contaminant distribution, either due to natural degradation or ongoing remediation.

  12. Assessing the Feasibility of DNAPL Source Zone Remediation: Review of Case Studies

    DTIC Science & Technology

    2004-05-01

    D.W., E.H. Hodgins , and B.J. Butler, 1991. Field and laboratory evidence of in situ biotransformation of tetrachloroethene to ethene and ethane at...Association Annual Meeting, St. Louis, June 22. Wadley, Sharon L.S., Robert W . Gillham. 2003. Laboratory and Field Investigations of DNAPL Source Zone...Extraction Zero Valent Iron Chemical Oxidation Excavation Pump and Treat Fe nt on ’s Re ag en t Pe rm an ga na te W a te r/ A ir Ex tra ct io n Ex

  13. Engineered Natural Geosorbents for In Situ Immobilization of DNAPLs and Heavy Metals

    SciTech Connect

    Walter J. Weber; Gordon M. Fair; Earnest Boyce

    2006-12-01

    Extensive subsurface contamination by dense non-aqueous phase liquid (DNAPL) organic solvents and heavy metals is common place at many DOE facilities. Poor performances and excessive costs have made traditional technologies and approaches less than satisfactory for remediation of such sites. It is increasingly apparent that marginal improvements in conventional methods and approaches will not suffice for clean up of many contaminated DOE sites. Innovative approaches using new and/or existing technologies in more efficient and cost-effective ways are thus urgently required.

  14. Analysis of urinary metabolic signatures of early hepatocellular carcinoma recurrence after surgical removal using gas chromatography-mass spectrometry.

    PubMed

    Ye, Guozhu; Zhu, Bin; Yao, Zhenzhen; Yin, Peiyuan; Lu, Xin; Kong, Hongwei; Fan, Fei; Jiao, Binghua; Xu, Guowang

    2012-08-03

    The objective of present study was to offer insights into the metabolic responses of hepatocellular carcinoma (HCC) to surgical resection and the metabolic signatures latent in early HCC recurrence (one year after operation). Urinary metabolic profiling employing gas chromatography time-of-flight mass spectrometry (GC-TOF MS) was utilized to investigate the complex physiopathologic regulations in HCC after operational intervention. It was revealed that an intricate series of metabolic regulations including energy metabolism, amino acid metabolism, nucleoside metabolism, tricarboxylic acid (TCA) cycle, gut floral metabolism, etc., principally leading to the direction of biomass synthesis, could be observed after tumor surgical removal. Moreover, metabolic differences between recurrent and nonrecurrent patients had emerged 7 days after initial operation. The metabolic signatures of HCC recurrence principally comprised notable up-regulations of lactate excretion, succinate production, purine and pyrimidine nucleosides turnover, glycine, serine and threonine metabolism, aromatic amino acid turnover, cysteine and methionine metabolism, and glyoxylate metabolism, similar to metabolic behaviors of HCC burden. Sixteen metabolites were found to be significantly increased in the recurrent patients compared with those in nonrecurrent patients and healthy controls. Five metabolites (ethanolamine, lactic acid, acotinic acid, phenylalanine and ribose) were further defined; they were favorable to the prediction of early recurrence.

  15. High-field FT-ICR mass spectrometry and NMR spectroscopy to characterize DOM removal through a nanofiltration pilot plant.

    PubMed

    Cortés-Francisco, Nuria; Harir, Mourad; Lucio, Marianna; Ribera, Gemma; Martínez-Lladó, Xavier; Rovira, Miquel; Schmitt-Kopplin, Philipe; Hertkorn, Norbert; Caixach, Josep

    2014-12-15

    Ultrahigh resolution Fourier transform ion cyclotron mass spectrometry and nuclear magnetic resonance spectroscopy were combined to evaluate the molecular changes of dissolved organic matter (DOM) through an ultrafiltration-nanofiltration (UF-NF) pilot plant, using two dissimilar NF membranes tested in parallel. The sampling was performed on seven key locations within the pilot plant: pretreated water, UF effluent, UF effluent after addition of reagents, permeate NF 1, permeate NF 2, brine NF 1 and brine NF 2, during two sampling campaigns. The study showed that there is no significant change in the nature of DOM at molecular level, when the water was treated with UF and/or with the addition of sodium metabisulfite and antiscaling agents. However, enormous decrease of DOM concentration was observed when the water was treated on the NF membranes. The NF process preferentially removed compounds with higher oxygen and nitrogen content (more hydrophilic compounds), whereas molecules with longer pure aliphatic chains and less content of oxygen were the ones capable of passing through the membranes. Moreover, slight molecular selectivity between the two NF membranes was also observed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Changes in concentrations of a TCE plume in near- stream zones of a DNAPL contaminated area adjacent to a stream

    NASA Astrophysics Data System (ADS)

    Lee, S.; Hyun, Y.; Lee, K.

    2012-12-01

    A field investigation of a trichloroethylene (TCE) groundwater plume originating at an industrial complex and its discharges to a stream nearby showed that apparent plume attenuation occurred in the near-stream zone of a DNAPL contaminated area adjacent to a stream prior to discharging to the stream. The concentrations of TCE and cis-1,2-dichloroethene (cis-DCE) in groundwater, hyporheic water, stream water and streambed, and hydrogeology were characterized using mini-piezometers, monitoring wells, Ground Penetrating Radar (GPR) surveys, and soil coring. In the near stream zones temporal and spatial TCE plume concentration changes and mass fluxes were investigated along the flowpath of groundwater discharging to the stream. It is evident that observed concentrations of contaminants (TCE and cis-DCE) were reduced in the near-stream zone, resulting that TCE and cis-DCE were not detected in the streambed and stream water. Ground GPR surveys done in the near stream zone found that wire and water treatment pipe conduits were buried under the ground next to the stream, which could lead groundwater flow field distortion in this zone. At streambed, the GPR survey and soil coring indicated the presence of low permeable zones consisting of rotten material deposits at the top of 0.3 m ~ 0.8 m underlain by silty sands. These hydrogeological features can also attribute to no detection of contaminants in the streambed and stream water because low permeable zone is an obstacle to effective interactions between groundwater and stream water. More investigations will be carried out for comprehensive understanding of hydrological and biogeochemical processes associated with TCE plume attenuation in near stream zones and streambed in the site.

  17. Phased implementation of in situ chemical oxidation for a large TCE DNAPL source Area at the Portsmouth gaseous diffusion plant

    SciTech Connect

    Cross, P.E.; Thompson, S.L.; Haskins, S.

    2007-07-01

    This paper describes the In Situ Chemical Oxidation (ISCO) remediation being implemented for the the X-701B groundwater plume at the Department of Energy (DOE) Portsmouth Gaseous Diffusion Plant (PORTS). Modified Fenton's reagent is the principal oxidant for the remedy, and Direct Push Technology (DPT) is being used for delivery of the oxidant. Trichloroethene (TCE) is the primary contaminant of concern and is present within the unit as a dense nonaqueous phase liquid (DNAPL). A phased approach is being implemented to optimize the type, location, and mass of the oxidant injections. During Phase I, a unique near-real time monitoring approach was utilized to observe the transient effects of the oxidant injections on the formation. As a result of the positive results from Phase I, Ohio EPA has approved the final work plan for the remedy, and the approach is now being applied to the source area of the plume. The results from Phase I and the layout for the first series of Phase II injections are presented in this paper. Previous testing at the site has shown that the shallow, water-bearing formation is primarily composed of silty gravel and clay, and is both heterogeneous and anisotropic. These factors have significantly compromised earlier attempts to remediate the unit. A patented ISCO process from In-Situ Oxidative Technologies, Inc. (ISOTEC) was selected for the remediation of the plume. Phase I results indicate that oxidant delivery via DPT is feasible for the unit. Contaminant reduction to date has been minimal due to the small quantity of oxidant injected during Phase I. Contaminant rebound in the aqueous phase remains a concern and will be monitored closely during the remedy. (authors)

  18. The Origin Of The Gaussian Initial Mass Function of Old Globular Cluster Systems: Impact Of The Residual Star Forming Gas Removal

    NASA Astrophysics Data System (ADS)

    Parmentier, G. A.; Gilmore, G. F.

    2006-08-01

    Evidence favouring a Gaussian cluster initial mass function (IMF) similar to that today for systems of old globular clusters (GC) has accumulated over recent years. We show that a bell-shaped cluster mass function may be the imprint of expulsion from the protocluster of the leftover star forming gas due to supernova activity. Owing to the corresponding weakening of its gravitational potential, the protocluster retains a fraction only of its newly formed stars. The mass fraction of bound stars extends from zero to unity depending on the star formation efficiency (SFE) achieved by the protoglobular cloud. We investigate how such wide variations affect the mapping of the protoglobular cloud mass function to the GC IMF. We assume that the protoglobular cloud mass spectrum obeys a power-law with spectral index between -2.5 and -1.5, as is observed for giant molecular clouds in the Local Group. Following convolution with an SFE probability distribution, we account for gas removal and derive the cluster initial mass (function) by combining each SFE value to the corresponding fraction of stars remaining bound to the protocluster. Although our simulations were started with power-law cloud mass distributions, the newly formed gas-free bound star clusters show bell-shaped mass functions, that is, little memory of the cloud mass distribution is retained. If the GC IMF is actually a bell-shape/Gaussian similar to that today, then the origin of the universal cluster mass at the present-day turnover is locked into the cluster formation process. We show that the turnover universality would originate mostly from a common value among galaxies for the lower mass limit of the protoglobular clouds, possibly with second-order variations driven by differences in the slope of the cloud mass spectrum, that of the SFE distribution, as well as by differences in the gas removal time-scale.

  19. Combining Experiments and Simulation of Gas Absorption for Teaching Mass Transfer Fundamentals: Removing CO2 from Air Using Water and NaOH

    ERIC Educational Resources Information Center

    Clark, William M.; Jackson, Yaminah Z.; Morin, Michael T.; Ferraro, Giacomo P.

    2011-01-01

    Laboratory experiments and computer models for studying the mass transfer process of removing CO2 from air using water or dilute NaOH solution as absorbent are presented. Models tie experiment to theory and give a visual representation of concentration profiles and also illustrate the two-film theory and the relative importance of various…

  20. Combining Experiments and Simulation of Gas Absorption for Teaching Mass Transfer Fundamentals: Removing CO2 from Air Using Water and NaOH

    ERIC Educational Resources Information Center

    Clark, William M.; Jackson, Yaminah Z.; Morin, Michael T.; Ferraro, Giacomo P.

    2011-01-01

    Laboratory experiments and computer models for studying the mass transfer process of removing CO2 from air using water or dilute NaOH solution as absorbent are presented. Models tie experiment to theory and give a visual representation of concentration profiles and also illustrate the two-film theory and the relative importance of various…

  1. Mass loss and nutrient concentrations of buried wood as a function of organic matter removal, soil compaction, and vegetation control in a regenerating oak-pine forest

    Treesearch

    Felix Ponder; John M. Kabrick; Mary Beth Adams; Deborah S. Page-Dumroese; Marty F. Jurgensen

    2017-01-01

    Mass loss and nutrient concentrations of northern red oak (Quercus rubra) and white oak (Q. alba) wood stakes were measured 30 months after their burial in the upper 10 cm of soil in a regenerating forest after harvesting and soil disturbance. Disturbance treatments were two levels of organic matter (OM) removal (only...

  2. Demonstration of ISCO Treatment of a DNAPL Source Zone at Launch Complex 34 in Cape Canaveral Air Station, FL

    EPA Science Inventory

    The Interagency DNAPL Consortium (IDC) was formally established in 1999 by the U.S. Department of Energy (DOE), U.S. Environmental Protection Agency (U.S. EPA), Department of Defense (DoD), and National Aeronautics and Space Administration as a vehicle for marshalling the resourc...

  3. Demonstration of ISCO Treatment of a DNAPL Source Zone at Launch Complex 34 in Cape Canaveral Air Station, FL

    EPA Science Inventory

    The Interagency DNAPL Consortium (IDC) was formally established in 1999 by the U.S. Department of Energy (DOE), U.S. Environmental Protection Agency (U.S. EPA), Department of Defense (DoD), and National Aeronautics and Space Administration as a vehicle for marshalling the resourc...

  4. Application of proton-transfer-reaction mass spectrometry to the assessment of odorant removal in a biological air cleaner for pig production.

    PubMed

    Hansen, Michael J; Liu, Dezhao; Guldberg, Lise Bonne; Feilberg, Anders

    2012-03-14

    There is an urgent need to develop odor reduction technologies for animal production facilities, and this requires a reliable measurement technique for estimating the removal of odorants. The purpose of the present experiment was to investigate the application of proton-transfer-reaction mass spectrometry (PTR-MS) for continuous measurements at a biofilter from SKOV A/S installed at a pig production facility. PTR-MS was able to handle the harsh conditions with high humidity and dust load in a biofilter and provide reliable data for the removal of odorants, including the highly odorous sulfur compounds. The biofilter removed 80-99% of carboxylic acids, aldehydes, ketones, phenols, and indoles and ca. 75% of hydrogen sulfide. However, only ~0-15% of methanethiol and dimethyl sulfide was removed. In conclusion, PTR-MS is a promising tool that can be used to improve the development of biological air cleaning and other odor reduction technologies toward significant odorants.

  5. Dip-angle influence on areal DNAPL recovery by co-solvent flooding with and without pre-flooding.

    PubMed

    Boyd, Glen R; Li, Minghua; Husserl, Johana; Ocampo-Gómez, Ana M

    2006-01-10

    A two-dimensional (2D) laboratory model was used to study effects of gravity on areal recovery of a representative dense non-aqueous phase liquid (DNAPL) contaminant by an alcohol pre-flood and co-solvent flood in dipping aquifers. Recent studies have demonstrated that injection of alcohol and co-solvent solutions can be used to reduce in-situ the density of DNAPL globules and displace the contaminant from the source zone. However, contact with aqueous alcohol reduces interfacial tension and causes DNAPL swelling, thus facilitating risk of uncontrolled downward DNAPL migration. The 2D laboratory model was operated with constant background gradient flow and a DNAPL spill was simulated using tetrachloroethene (PCE). The spill was dispersed to a trapped, immobile PCE saturation by a water flood. Areal PCE recovery was studied using a double-triangle well pattern to simulate a remediation scheme consisting of an alcohol pre-flood using aqueous isobutanol ( approximately 10% vol.) followed by a co-solvent flood using a solution of ethylene glycol (65%) and 1-propanol (35%). Experiments were conducted with the 2D model oriented in the horizontal plane and compared to experiments at the 15 degrees and 30 degrees dip-angle orientations. Injection was applied either in the downward or upward direction of flow. Experimental results were compared to theoretical predictions for flood front stability and used to evaluate effects of gravity on areal PCE recovery. Sensitivity experiments were performed to evaluate effects of the alcohol pre-flood on PCE areal recovery. For experiments conducted with the alcohol pre-flood and the 2D model oriented in the horizontal plane, results indicate that 89-93% of source zone PCE was recovered. With injection oriented downward, results indicate that areal PCE recovery was 70-77% for a 15 degrees dip angle and 57-59% for a 30 degrees dip angle. With injection oriented upward, results indicate that areal PCE recovery was 57-60% at the 30

  6. Material Property Estimation for Direct Detections of DNAPL using Integrated Ground-Penetrating Radar Velocity, Imaging and Attribute Analysis

    SciTech Connect

    Bradford, John; Smithson, Scott B.; Holbrook, W. Stephen

    2004-06-14

    The focus of our work is direct detection of DNAPLs, specifically chlorinated solvents, via material property estimation from surface ground-penetrating radar (GPR) data. We combine sophisticated GPR processing methodology with quantitative attribute analysis and material property estimation to determine the location and extent of residual and/or pooled DNAPL in both the vadose and saturated zones. An important byproduct of our research is state-of-the-art imaging which allows us to pinpoint attribute anomalies, characterize stratigraphy, identify fracture zones, and locate buried objects. Implementation and verification of these methodologies will be a significant advance in GPR research and in meeting DOE's need for reliable in-situ characterization of DNAPL contamination. Chlorinated solvents have much lower electric permittivity and conductivity than water. An electrical property contrast is induced when solvents displace water in the sediment column resulting in an anomalous GPR signature. To directly identify zones of DNAPL contamination, we focus on three aspects of reflected wave behavior--propagation velocity, frequency dependent attenuation, and amplitude variation with offset (AVO). Velocity analysis provides a direct estimate of electric permittivity, attenuation analysis provides a measure of conductivity, and AVO behavior is used to estimate the permittivity ratio at a reflecting boundary. Areas of anomalously low electric permittivity and conductivity are identified as potential DNAPL rich zones. Preliminary work illustrated significant potential for quantitative direct detection methodologies in identifying shallow DNAPL source zones. It is now necessary to verify these methodologies in a field setting. To this end, the project is field oriented and has three primary objectives: (1) Develop a suite of methodologies for direct detection of DNAPLs from surface GPR data (2) Controlled field verification at well characterized, contaminated sites (3

  7. Material Property Estimation for Direct Detection of DNAPL using Integrated Ground-Penetrating Radar Velocity, Imaging and Attribute Analysis

    SciTech Connect

    Bradford, John; Smithson, Scott B.; Holbrook, W. Stephen

    2003-06-01

    The focus of our work is direct detection of DNAPLs, specifically chlorinated solvents, via material property estimation from surface ground-penetrating radar (GPR) data. We combine sophisticated GPR processing methodology with quantitative attribute analysis and material property estimation to determine the location and extent of residual and/or pooled DNAPL in both the vadose and saturated zones. An important byproduct of our research is state-of-the-art imaging which allows us to pinpoint attribute anomalies, characterize stratigraphy, identify fracture zones, and locate buried objects. Implementation and verification of these methodologies will be a significant advance in GPR research and in meeting DOE's need for reliable in-situ characterization of DNAPL contamination. Chlorinated solvents have much lower electric permittivity and conductivity than water. An electrical property contrast is induced when solvents displace water in the sediment column resulting in an anomalous GPR signature. To directly identify zones of DNAPL contamination, we focus on three aspects of reflected wave behavior--propagation velocity, frequency dependent attenuation, and amplitude variation with offset (AVO). Velocity analysis provides a direct estimate of electric permittivity, attenuation analysis provides a measure of conductivity, and AVO behavior is used to estimate the permittivity ratio at a reflecting boundary. Areas of anomalously low electric permittivity and conductivity are identified as potential DNAPL rich zones. Preliminary work illustrated significant potential for quantitative direct detection methodologies in identifying shallow DNAPL source zones. It is now necessary to verify these methodologies in a field setting. To this end, the project is field oriented and has three primary objectives: (1) Develop a suite of methodologies for direct detection of DNAPLs from surface GPR data (2) Controlled field verification at well characterized, contaminated sites (3

  8. Assessment of trace organic chemical removal by a membrane bioreactor using gas chromatography/mass spectrometry and a yeast screen bioassay.

    PubMed

    Coleman, Heather M; Troester, Martin; Khan, Stuart J; McDonald, James A; Watkins, Graeme; Stuetz, Richard M

    2009-12-01

    A membrane bioreactor (MBR) was assessed for the removal of estrogens, androgens, and a selection of pharmaceuticals and personal care products. The biomass and aqueous components of the MBR were investigated to determine whether removal was by biodegradation or by adsorption to the biomass. Removal was monitored using chemical analysis by gas chromatography/mass spectrometry (GC-MS) as well as biological analysis using estrogenic and androgenic yeast assays. Results showed that the MBR was effective in removing the compounds of concern from raw influent with removal rates between 78 and 99%. Removal efficiencies were comparable or better than those reported for conventional activated sludge systems, which was attributed to the relatively high sludge retention time of the MBR. The biomass component showed significant concentrations of salicylic acid, triclosan, and 4-tert-octylphenol. Estrogenic and androgenic activity was also measured in the biomass. Estrone was identified as the main compound responsible for the estrogenic activity. It was concluded that the main removal pathway was biodegradation, but sorption to biomass may also be important, particularly for triclosan and 4-tert-octylphenol.

  9. The Use of Molecular and Genomic Techniques Applied to Microbial Diversity, Community Structure, and Activities at DNAPL and Metal Contaminated Sites

    EPA Science Inventory

    A wide variety of in situ subsurface remediation strategies have been developed to mitigate contamination by chlorinated solvent dense non-aqueous phase liquids (DNAPLS) and metals. Geochemical methods include: zerovalent iron emplacement, various electrolytic applications, elec...

  10. The Use of Molecular and Genomic Techniques Applied to Microbial Diversity, Community Structure, and Activities at DNAPL and Metal Contaminated Sites

    EPA Science Inventory

    A wide variety of in situ subsurface remediation strategies have been developed to mitigate contamination by chlorinated solvent dense non-aqueous phase liquids (DNAPLS) and metals. Geochemical methods include: zerovalent iron emplacement, various electrolytic applications, elec...

  11. Containment and restoration technology development for DNAPL in fractured bedrock (an overview of the Smithville Phase IV Program)

    SciTech Connect

    O`Neill, J.E.

    1997-12-31

    Currently, no proven technology exists for containing and restoring fractured carbonate bedrock environments that have been contaminated by Dense Nonaqueous Phase Liquids (DNAPLs). Over the past decade Canada`s Orphan Sites Program and the US Superfund Program have spent billions of dollars on site restoration and yet not one DNAPL site has ever been successfully cleaned-up. Current research and technology development efforts are generally less than five years old and have focused on porous media research. Fractured media flow and contaminant transport are recognized as much more complex issues, but have received comparatively little attention. It is estimated that there are hundreds of fractured rock DNAPL contaminated sites in Canada and the United States. The Smithville Phase IV Bedrock Remediation Program was established to contain and remediate a DNAPL spill site in a carbonate bedrock aquifer located in the Niagara region, Canada. The program recognizes the need to develop new technical solutions and is doing this through site specific investigations, laboratory studies, modelling and pilot scale tests of promising containment and restoration technologies. An innovative management structure has been established to direct the final stage of this project through an agreement of common interest with all former stakeholders. This independent Board`s directive is to contain and remediate the DNAPL remaining in the ground beneath and adjacent to the site and to form partnerships with world-renowned scientists and researchers to develop and implement leading edge technology. This paper provides an overview of the challenges, plans and accomplishments of the Smithville remediation project. The innovative management approach applied at the site has reduced bureaucracy and costs and has promoted partnership and consortia arrangements that are now being realized for site funding.

  12. Prediction and minimization of vertical migration of DNAPLS using surfactant enhanced aquifer remediation at neutral buoyancy

    NASA Astrophysics Data System (ADS)

    Shook, G. Michael; Pope, Gary A.; Kostarelos, K.

    1998-11-01

    Surfactant enhanced aquifer remediation (SEAR) had previously been thought to require a capillary barrier below the contaminated zone to prevent the vertical migration of a microemulsion containing solubilized DNAPL. This paper shows the vertical migration of the dense microemulsion is described and predicted by the value of three dimensionless scaling groups. Embedded within these scaling groups are four design parameters. The value of these parameters can be manipulated in order to reduce the amount of vertical migration anticipated for a given remediation design. Plots have been constructed that illustrate the relationship between vertical migration and the value of the scaling groups; such plots can be used to predict vertical migration and to determine appropriate screen intervals of extraction wells to ensure full capture of the contaminants. This predictive capability has been verified in laboratory experiments. Predicted migration of the microemulsion agreed within about 2% of that observed. Development of the scaling groups is presented, remediation design implications are discussed, and laboratory verification is shown. Additional discussion of the laboratory work is given in a companion paper [Kostarelos, K., Pope, G.A., Rouse, B.A., Shook, G.M., 1998. A new concept: the use of neutrally-buoyant microemulsions for DNAPL remediation, J. Contam. Hydro., this edition].

  13. Effects of surface active agents on DNAPL migration and distribution in saturated porous media.

    PubMed

    Cheng, Zhou; Gao, Bin; Xu, Hongxia; Sun, Yuanyuan; Shi, Xiaoqing; Wu, Jichun

    2016-11-15

    Dissolved surface active agents such as surfactant and natural organic matter can affect the distribution and fate of dense nonaqueous liquids (DNAPLs) in soil and groundwater systems. This work investigated how two common groundwater surface active agents, humic acid (HA) and Tween 80, affected tetrachloroethylene (PCE) migration and source zone architecture in saturated porous media under environmentally relevant conditions. Batch experiments were first conducted to measure the contact angles and interfacial tensions (IFT) between PCE and quartz surface in water containing different amount of surface active agents. Results showed that the contact angle increased and IFT decreased with concentration of surface active agent increasing, and Tween 80 was much more effective than HA. Five 2-D flow cell experiments were then conducted. Correspondingly, Tween 80 showed strong effects on the migration and distribution of PCE in the porous media due to its ability to change the medium wettability from water-wet into intermediate/NAPL-wet. The downward migration velocities of the PCE in three Tween 80 cells were slower than those in the other two cells. In addition, the final saturation of the PCE in the cells containing surface active agents was higher than that in the water-only cell. Results from this work indicate that the presence of surface active agents in groundwater may strongly affect the fate and distribution of DNAPL through altering porous medium wettability. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Dissolution of an emplaced source of DNAPL in a natural aquifer setting.

    PubMed

    Rivett, Michael O; Feenstra, Stanley

    2005-01-15

    Field-scale dissolution of a multicomponent DNAPL (dense nonaqueous-phase liquid) source intentionally emplaced below the water table is evaluated in a well-characterized natural aquifer setting. The block-shaped source contained 23 kg of a trichloromethane, trichloroethene, and perchloroethene mixture homogeneously distributed at 5% saturation of pore space. Dissolution was monitored for 3 yr via down-gradient samplers (1-m fence) and occasional intra-source sampling. Although intra-source equilibrium dissolution was shown and endorsed by supporting modeling and literature lab data, less than equilibrium concentrations were predominantly monitored in the 1-m fence. This was ascribed to significant by-passing of the source by groundwater flow due to its low permeability relative to the aquifer and associated dilution of concentrations emitted from the source. Heterogeneous source dissolution occurred despite the relative homogeneity of the source and aquifer and was ascribed to dissolution fingering, which has not been previously field-demonstrated. Bulk bypass of groundwater flow around the source zone caused slow dissolution rates, with 77% of the source remaining after 3 yr and a projected longevity of approximately 25 yr. Observed dissolution fingering would have significantly increased longevity as it increasingly caused intra-source bypass of remaining DNAPL. Our dissolution interpretations were endorsed by additional data collected after 6 yr during source remediation via permanganate oxidation.

  15. Improved isotope ratio measurement performance in liquid chromatography/isotope ratio mass spectrometry by removing excess oxygen.

    PubMed

    Hettmann, Elena; Brand, Willi A; Gleixner, Gerd

    2007-01-01

    A low dead volume oxygen scrubbing system was introduced in a commercially available liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) interface to enhance the analytical capability of the system. In the LC/IRMS interface carbon from organic samples is converted into CO(2) inside the mobile phase by wet chemical oxidation using peroxodisulfate (Na(2)S(2)O(8)). After passing the hot reaction zone, surplus oxygen (O(2)) remains dissolved in the liquid phase. Both CO(2) and O(2) diffuse through a transfer membrane into the helium carrier and are transferred to the mass spectrometer. The presence of O(2) in the ion source may have detrimental effects on measurement accuracy and precision as well as on filament lifetime. As a remedy, a new on-line O(2)-removing device has been incorporated into the system. The new O(2) scrubber consists of two parallel hot copper reduction reactors (0.8 mm i.d., active length 120 mm) and a switch-over valve between them. One reactor is regenerated using He/H(2) while the other is actively scavenging O(2) from the gas stream. The capacity of each reduction reactor, expressed as usage time, is between 40 and 50 min. This is sufficient for a single LC run for sugars and organic acids. A further increase of the reduction capacity is accompanied by a peak broadening of about 100%. After switching to a freshly reduced reactor the oxygen background and the delta(13)C values of the reference gas need up to 500 s to stabilize. For repeated injections the delta(13)C values of sucrose remain constant (+/-0.1 per thousand) for about 3000 s. The long-term stability for measurements of sucrose was 0.11 per thousand without the reduction oven and improved slightly to 0.08 per thousand with the reduction oven. The filament lifetime improved by more than 600%, thereby improving the long-term system stability and analytical efficiency. In addition the costs per analysis were reduced considerably.

  16. The efficiency evaluation of in situ remediation performed around the source zone of DNAPL contaminated site, Wonju, Korea

    NASA Astrophysics Data System (ADS)

    Lee, S. S.; Lee, S. H.; Lee, K. K.

    2014-12-01

    The location of DNAPL source and distribution of contaminant plume at an industrial complex, Wonju, Korea, was examined based on the combined results of seasonal impact analysis, historical approach, radon tracer approach, and chemical fingerprinting conducted from 2009 to 2013 (Yang et al., 2013). With regard to the amount of contaminants discharged at this study site, there is no exact information on disposal. Therefore, various remediation technologies such as soil vapor extraction, soil flushing, biostimulation, and pump-and-treatment have been performed to eliminate the contaminant sources of trichloroethylene (TCE) and to prevent the migration of TCE plume from remediation target zones. Also, dissolved TCE concentration and mass of residual TCE in the initial stage of disposal were estimated to evaluate the efficiency of in situ remediation. The remediation efficiency according to the remediation actions was evaluated by tracing a time-series of plume evolution and estimating the temporal mass discharge at three transects (Source, Transec-1, Transect-2) which was assigned along the groundwater flow path. From results of periodically monitored TCE concentration at main source zone, the TCE level (15.74 mg/L) before the remediation dramatically decreased up to 0.56 mg/L at the end of year 2012 due to the effect of remediation. During the intensive remediation period from 2012 to 2013, the early average mass discharge (26.58 g/day) at source transect was decreased to average 4.99 g/day. Especially, in case of surfactant flushing test which was conducted to eliminate the residual TCE, the efficiency of surfactant flushing test was evaluated using the recovery rate of chloride ion which was used as tracer. The results for recovery rate of chloride ion show that test wells observed the slow recovery rate represented more effective dissolution of TCE than wells showing the rapid recovery rate. By using the source zone monitoring data and analytical solution, initial

  17. SATURATION MEASUREMENT OF IMMISCIBLE FLUIDS IN 2-D STATIC SYSTEMS: VALIDATION BY LIGHT TRANSMISSION VISUALIZATION (SAN FRANCISCO, CA)

    EPA Science Inventory

    This study is a part of an ongoing research project that aims at assessing the environmental benefits of DNAPL removal. The laboratory part of the research project is to examine the functional relationship between DNAPL architecture, mass removal and contaminant mass flux in 2-D ...

  18. SATURATION MEASUREMENT OF IMMISCIBLE FLUIDS IN 2-D STATIC SYSTEMS: VALIDATION BY LIGHT TRANSMISSION VISUALIZATION (SAN FRANCISCO, CA)

    EPA Science Inventory

    This study is a part of an ongoing research project that aims at assessing the environmental benefits of DNAPL removal. The laboratory part of the research project is to examine the functional relationship between DNAPL architecture, mass removal and contaminant mass flux in 2-D ...

  19. Stochastic Approach for Modeling of DNAPL Migration in Heterogeneous Aquifers: Model Development and Experimental Data Generation

    NASA Astrophysics Data System (ADS)

    Dean, D. W.; Illangasekare, T. H.; Turner, A.; Russell, T. F.

    2004-12-01

    Modeling of the complex behavior of DNAPLs in naturally heterogeneous subsurface formations poses many challenges. Even though considerable progress have been made in developing improved numerical schemes to solve the governing partial differential equations, most of these methods still rely on deterministic description of the processes. This research explores the use of stochastic differential equations to model multiphase flow in heterogeneous aquifers, specifically the flow of DNAPLs in saturated soils. The models developed are evaluated using experimental data generated in two-dimensional test systems. A fundamental assumption used in the model formulation is that the movement of a fluid particle in each phase is described by a stochastic process and that the positions of all fluid particles over time are governed by a specific law. It is this law, which we seek to determine. The approach results in a nonlinear stochastic differential equation describing the position of the non-wetting phase fluid particle. The nonlinearity in the stochastic differential equation arises because both the drift and diffusion coefficients depend on the volumetric fraction of the phase, which in turn depends on the position of the fluid particles in the problem domain. The concept of a fluid particle is central to the development of the proposed model. Expressions for both saturation and volumetric fraction are developed using this concept of fluid particle. Darcy's law and the continuity equation are used to derive a Fokker-Planck equation governing flow. The Ito calculus is then applied to derive a stochastic differential equation(SDE) for the non-wetting phase. This SDE has both drift and diffusion terms which depend on the volumetric fraction of the non-wetting phase. Standard stochastic theories based on the Ito calculus and the Wiener process and the equivalent Fokker-Planck PDE's are typically used to model diffusion processes. However, these models, in their usual form

  20. Quantitative assessment of electrical resistivity tomography for monitoring DNAPLs migration - Comparison with high-resolution light transmission visualization in laboratory sandbox

    NASA Astrophysics Data System (ADS)

    Deng, Yaping; Shi, Xiaoqing; Xu, Hongxia; Sun, Yuanyuan; Wu, Jichun; Revil, André

    2017-01-01

    Real-time monitoring of dense non-aqueous phase liquids (DNAPLs) migration and distribution is essential for the decision of an effective remediation strategy. Light transmission visualization (LTV) has shown its accuracy and efficiency for measuring DNAPLs saturation and water content in the laboratory, but it cannot be implemented in three dimensional sandbox or field-scale sites. Recently developed electrical resistivity tomography (ERT) has been applied in monitoring the migration and distribution of DNAPLs in bench- and field-scale studies. However, the evaluation of the ability of ERT for monitoring DNAPLs migration by a direct comparison of ERT with high-resolution techniques such as LTV within an experimental system is still lacking. Two sandbox experiments with different permeability conditions are conducted to quantitatively assess the capability of ERT for monitoring the DNAPLs migration. During the injections, LTV method is used to visualize the DNAPLs migration and provide high-resolution saturation data while ERT method is applied to capture the change of resistivity. The results from the comparison between LTV and ERT methods show that ERT is successful in detecting the accumulation and flow bypassing phenomenon around the low-permeability lenses, as well as the penetration through the high-permeability lenses. There is a fair correlation between the resistivity and saturation with overall correlation coefficients above 0.6, except at last stage. However, using classical regularization techniques (based on smoothness), the area of DNAPLs plume determined by ERT is commonly overestimated. Compared to the plume around the low-permeability lenses, the plume around the high-permeability lenses estimated by ERT is more extensive due to larger resistivity contrasts. In addition, ERT measurements indicate that the resistivity increase caused by the low-saturation DNAPLs is not apparent enough, which is likely to be covered up under the changing

  1. Sampling results, DNAPL monitoring well GW-726, Oak Ridge Y-12 plant, Oak Ridge, Tennessee. Quarterly report, April 1, 1994--September 30, 1994.

    SciTech Connect

    1995-12-31

    In January 1990, dense, non aqueous phase liquids (DNAPLs) were discovered at a depth of approximately 274 foot below ground surface along the southern border of the Y-12 Plant Burial Grounds. Immediately after the discovery, an investigation was conducted to assess the occurrence of DNAPL at the site and to make recommendations for further action. This report summarizes purging and sampling activities for one of these multiport wells, GW-726, and presents analytical results for GW-726.

  2. [Analysis of rice leaves proteomes by liquid chromatography-tandem, mass spectrometry based on the purification using a novel affinity detergent removal spin column].

    PubMed

    Cao, Xiaolin; Gong, Jiadi; Chen, Mingxue; Yu, Shasha; Bian, Yingfang; Cao, Zhaoyun

    2014-11-01

    A purification method was established for the analysis of proteomes in rice leaves based on a novel detergent removal spin column (DRSC). The proteins were extracted by phenol protein extraction method followed by sodium dodecyl sulfate (SDS) lysis. The lysate was purified by the detergent removal spin column and the enzymolytic peptides were detected by the nanoflow liquid chromatography-hybrid linear trap quadrupole orbitrap mass spectrometry (nanoLC-LTQ/Orbitrap). In terms of SDS removal efficiencies and protein identification, the method of DRSC was compared with those of filter aided sample preparation (FASP) and acetone precipitation. As a result, there were good efficiencies ( > 95%) of SDS removal for the three methods. With the DRSC purification strategy, 563 proteins were identified from rice leaves, while only 196 and 306 proteins were identified by FASP and acetone precipitation procedures respectively, in spite of certain complementarities among these identified proteins by the three methods. DRSC is suitable for proteins with various relative molecular masses and pI values. However, there were similar losses of proteins with different relative molecular masses and pI values with the other two methods. Using the established method, 588 proteins were identified by once injection analysis. According to the molecular functions, 296 proteins with at least two identified peptides can be classified into eight categories with binding activity, enzyme activity, transporter activity, inhibitor activity, structural constitute, catalytic activity, other and unknown functions. The method provides technical reference for conducting rice proteomes.

  3. Mass

    SciTech Connect

    Quigg, Chris

    2007-12-05

    In the classical physics we inherited from Isaac Newton, mass does not arise, it simply is. The mass of a classical object is the sum of the masses of its parts. Albert Einstein showed that the mass of a body is a measure of its energy content, inviting us to consider the origins of mass. The protons we accelerate at Fermilab are prime examples of Einsteinian matter: nearly all of their mass arises from stored energy. Missing mass led to the discovery of the noble gases, and a new form of missing mass leads us to the notion of dark matter. Starting with a brief guided tour of the meanings of mass, the colloquium will explore the multiple origins of mass. We will see how far we have come toward understanding mass, and survey the issues that guide our research today.

  4. Mass

    SciTech Connect

    Chris Quigg

    2007-12-05

    In the classical physics we inherited from Isaac Newton, mass does not arise, it simply is. The mass of a classical object is the sum of the masses of its parts. Albert Einstein showed that the mass of a body is a measure of its energy content, inviting us to consider the origins of mass. The protons we accelerate at Fermilab are prime examples of Einsteinian matter: nearly all of their mass arises from stored energy. Missing mass led to the discovery of the noble gases, and a new form of missing mass leads us to the notion of dark matter. Starting with a brief guided tour of the meanings of mass, the colloquium will explore the multiple origins of mass. We will see how far we have come toward understanding mass, and survey the issues that guide our research today.

  5. Removal of ordering ambiguity for a class of position dependent mass quantum systems with an application to the quadratic Liénard type nonlinear oscillators

    SciTech Connect

    Chithiika Ruby, V.; Senthilvelan, M.; Lakshmanan, M.; Chandrasekar, V. K.

    2015-01-15

    We consider the problem of removal of ordering ambiguity in position dependent mass quantum systems characterized by a generalized position dependent mass Hamiltonian which generalizes a number of Hermitian as well as non-Hermitian ordered forms of the Hamiltonian. We implement point canonical transformation method to map one-dimensional time-independent position dependent mass Schrödinger equation endowed with potentials onto constant mass counterparts which are considered to be exactly solvable. We observe that a class of mass functions and the corresponding potentials give rise to solutions that do not depend on any particular ordering, leading to the removal of ambiguity in it. In this case, it is imperative that the ordering is Hermitian. For non-Hermitian ordering, we show that the class of systems can also be exactly solvable and is also shown to be iso-spectral using suitable similarity transformations. We also discuss the normalization of the eigenfunctions obtained from both Hermitian and non-Hermitian orderings. We illustrate the technique with the quadratic Liénard type nonlinear oscillators, which admit position dependent mass Hamiltonians.

  6. Nitrate removal under different ecological remediation measures in Taihu Lake: a 15N mass-balance approach.

    PubMed

    Liu, Dandan; Li, Zhengkui; Zhang, Wanguang

    2014-12-01

    Ecological remediation is an important measure for the protection of lake water quality in removing nutrients, such as nitrate (NO3 (-)). In this study, four bioremediation processes (bare sediment, immobilized nitrogen cycling bacteria (INCB) added, Elodea nuttallii added, E. nuttallii-INCB assemblage) were operated at a lab to elucidate the effect of macrophyte appearance and INCB addition on NO3 (-) removal and achieve the optimal processes for biomediation. (15) N-NO3 solution was added to microcosms to identify the key nitrogen transformation processes responsible for NO3 (-) removal. Results showed that nitrate removal was significantly enhanced after the addition of INCB and E. nuttallii. In the treatments with INCB added, E. nuttallii added, and INCB and E. nuttallii-INCB assemblage, nitrate removal ratio achieved 94.74, 98.76, and 99.15 %, respectively. In contrast, only 23.47 % added nitrate was removed in the control. Plant uptake and denitrification played an important role in nitrogen removal. The water quality was substantially improved by the addition of INCB and macrophyte that can accelerate denitrification and promote nitrogen assimilation of plants. The results indicated that plant uptake and microbial denitrification were key processes for nitrate removal.

  7. NON-INVASIVE DETERMINATION OF THE LOCATION AND DISTRIBUTION OF FREE-PHASE DENSE NONAQUEOUS PHASE LIQUIDS (DNAPL) BY SEISMIC REFLECTION TECHNIQUES

    SciTech Connect

    Michael G. Waddell; William J. Domoracki; Tom J. Temples

    2001-05-01

    This semi-annual technical progress report is for Task 4 site evaluation, Task 5 seismic reflection design and acquisition, and Task 6 seismic reflection processing and interpretation on DOE contact number DE-AR26-98FT40369. The project had planned one additional deployment to another site other than Savannah River Site (SRS) or DOE Hanford. During this reporting period the project had an ASME peer review. The findings and recommendation of the review panel, as well at the project team response to comments, are in Appendix A. After the SUBCON midyear review in Albuquerque, NM and the peer review it was decided that two additional deployments would be performed. The first deployment is to test the feasibility of using non-invasive seismic reflection and AVO analysis as monitoring to assist in determining the effectiveness of Dynamic Underground Stripping (DUS) in removal of DNAPL. Under the rescope of the project, Task 4 would be performed at the Charleston Navy Weapons Station, Charleston, SC and not at the Dynamic Underground Stripping (DUS) project at SRS. The project team had already completed Task 4 at the M-area seepage basin, only a few hundred yards away from the DUS site. Because the geology is the same, Task 4 was not necessary. However, a Vertical Seismic Profile (VSP) was conducted in one well to calibrate the geology to the seismic data. The first deployment to the DUS Site (Tasks 5 and 6) has been completed. Once the steam has been turned off these tasks will be performed again to compare the results to the pre-steam data. The results from the first deployment to the DUS site indicated a seismic amplitude anomaly at the location and depths of the known high concentrations of DNAPL. The deployment to another site with different geologic conditions was supposed to occur during this reporting period. The first site selected was DOE Paducah, Kentucky. After almost eight months of negotiation, site access was denied requiring the selection of another site

  8. Biological degradation of dense nonaqueous phase liquids (DNAPLs)

    SciTech Connect

    Ensley, B.; Strong-Gunderson, J.M.; Palumbo, A.V.

    1996-08-01

    In situ bioremediation is a very attractive, safe and efficient method of not only removing, but eliminating hazardous compounds from the environment. However, the quickest and most efficient method of restoring a hazardous waste site would be to link several remediation processes. In situ biodegradation can involve the addition of nutrients, oxygen, electron donors, electron acceptors, organisms or all the above. These amendments can be introduced and coupled to a variety of other technologies such as permeability enhancements, chemical treatments and/or physical processes. In addition to in situ technologies, bioremediation in bioreactors is an efficient tool facilitating mineralization of contaminants. Overall, biodegradation has a significant potential to increase the rate of site restoration and decrease overall costs. 37 refs., 2 figs.

  9. NON-INVASIVE DETERMINATION OF THE LOCATION AND DISTRIBUTION OF FREE-PHASE DENSE NONAQUEOUS PHASE LIQUIDS (DNAPL) BY SEISMIC REFLECTION TECHNIQUES

    SciTech Connect

    Michael G. Waddell; William J. Domoracki; Tom J. Temples

    2001-05-01

    This semi-annual technical progress report is for part of Task 4 (site evaluation), on DOE contact number DE-AR26-98FT40369. The project had planned one additional deployment to another site other than Savannah River Site (SRS) or DOE Hanford. After the SUBCON midyear review in Albuquerque, NM, it was decided that two additional deployments would be performed. The first deployment is to test the feasibility of using non-invasive seismic reflection and AVO analysis as monitoring to assist in determining the effectiveness of Dynamic Underground Stripping (DUS) in removal of DNAPL. The Second deployment site is the Department of Defense (DOD) Charleston Navy Weapons Station, Solid Waste Management Unit 12 (SWMU-12) Charleston, SC was selected in consultation with National Energy Technology Laboratory (NETL) and DOD Navy Facilities Engineering Command Southern Division (NAVFAC) personnel. Base upon the review of existing data and due to the shallow target depth the project team has collected three Vertical Seismic Profiles (VSP) and experimental reflection line. At the time of preparing this report VSP data and experimental reflection line data has been collected and has have preliminary processing on the data sets.

  10. Initial Results of ISCO for a Large TCE DNAPL Source Area

    SciTech Connect

    Thompson, S.L.; Cross, P.E.

    2008-07-01

    This paper will describe the results of an in situ chemical oxidation (ISCO) remedial action currently in progress to address subsurface contamination by trichloroethene (TCE) dense nonaqueous phase liquid (DNAPL). The U.S. Department of Energy is responsible for the cleanup of environmental media at the Portsmouth Gaseous Diffusion Plant (PORTS) in southern Ohio. The X-701B Solid Waste Management Unit is an unlined surface impoundment at PORTS which was operated from 1954 to 1988. A TCE plume in groundwater emanates from the unit and is approximately 2,200 feet in length. Metals, radioactive inorganics, and other organic chemicals are also present at lower concentrations in the groundwater. An ongoing 1.6-acre TCE DNAPL source area for the plume is believed to exist up-gradient in the vicinity of the X-701B pond. The extent of the source area is inferred from actual recovery of DNAPL in production wells and from detection of TCE concentrations between 100 and 1,000 mg/L in monitoring wells. Previous remedial activities at X-701B have included a Resource Conservation and Recovery Act (RCRA) closure and a technology demonstration that recirculated permanganate solutions between two horizontal wells. Results of sampling after these remedial activities showed that the permanganate effectively destroyed TCE in portions of the aquifer where adequate contact was achieved, but that uniform distribution by the recirculation system was problematic. As a result, the TCE concentration in the groundwater eventually rebounded after the treatment. To overcome distribution issues and to more aggressively remediate the source, a new remediation approach is being implemented for the unit. The new approach involves the injection of Modified Fenton's Reagent directly into the source area using temporary direct push injection points. This new approach provides the ability to overcome limitations imposed by heterogeneities in the subsurface by injecting relatively small quantities of

  11. Exploring Mass Flux Response to Local Source Zone Properties Using a Coupled-Process Adjoint Sensitivity Method

    NASA Astrophysics Data System (ADS)

    Tang, T.; Miller, E. L.; Abriola, L. M.

    2016-12-01

    Contaminant plumes emanating from DNAPL source zones pose substantial risks to the general population by transporting pollutants to receptor points. Thus, to assess potential risk, the quantification of down gradient mass flux and mass discharge has been identified as a critical component of source zone characterization. These metrics, however, are difficult to measure directly and are typically controlled by the complex interplay of a number of transport mechanisms. In an effort to improve the accuracy and efficiency of site characterization, this work employs an adjoint sensitivity method to quantify the importance of local system properties, given some initial site characterization information, on down gradient mass flux and plume persistence. Local properties that are considered in this research include: permeability, DNAPL saturation, and dissolved and sorbed contaminant mass concentrations. The utility of the adjoint sensitivity method is examined using, numerically generated, 3D heterogeneous DNAPL source zones. Conditioned spatial distributions of the four properties are generated using a joint probabilistic model associated with texture simulations based on field borehole measurements. An existing modular three-dimensional transport simulator, MT3DMS, is applied to solve the transport equation considering both DNAPL dissolution and linear and rate-limited sorption. Consistent with this process coupling, a subroutine is added to the code to solve the adjoint states, which evolves backward in time. Sensitivity analyses are developed to investigate the down-gradient plume response to the perturbation of the four local system properties. In addition, sensitivities corresponding to these four properties at different times are also compared, to explore the influence of DNAPL dissolution and desorption over time. Results demonstrate that the initial aqueous phase concentration will have a larger impact on downstream mass flux at early times after a DNAPL release

  12. Investigation of Chemical Reactivity, Mass Recovery and Biological Activity During Thermal Treatment of DNAPL Source Zones

    DTIC Science & Technology

    2009-10-01

    Radioactive Waste Treatment Technologies Handbook . C.H. Oh (Ed.), CRC Press, Boca Raton, FL, Chapter 4.6. Stookey, L.L. 1970. Ferrozine - A new...Research h hour H hydrogen H+ hydrogen ion H2 hydrogen gas H2CO3 carbonic acid HFK Helgeson-Kirkham- Flowers HP Hewlett-Packard HPLC...using the Helgeson-Kirkham- Flowers (HKF) equation of state. A final feature of Figure 4-6 concerns the entropy of vaporization, which increased with

  13. Mass Transfer from Entrapped DNAPL Sources Undergoing Remediation: Characterization Methods and Prediction Tools

    DTIC Science & Technology

    2006-08-31

    171 Figure 3.111 PCE Solubility as a Function of Temperature...O bs er ve d C on ce nt ra tio n of D is so lv ed E th en e C he m ic al s i n th e R F Ta nk O ne M on th a fte r I no cu la tio n 171 ...G.E. Hoag, P. Chheda, B.A. Woody, and G.M. Dobbs (2002) Kinetics and mechanism of oxidation of tetrachloroethylene with permanganate, Chemosphere , 46(6

  14. Dense Nonaqueous-Phase Liquid Architecture in Fractured Bedrock: Implications for Treatment and Plume Longevity.

    PubMed

    Schaefer, Charles E; White, Erin B; Lavorgna, Graig M; Annable, Michael D

    2016-01-05

    Partitioning tracer testing was performed in discrete intervals within a fractured bedrock tetrachloroethene (PCE) dense nonaqueous-phase liquid (DNAPL) source area to assess the fracture flow field and DNAPL architecture. Results confirmed that the partitioning tracer testing was able to identify and quantify low levels of residual DNAPL along flow paths in hydraulically conductive fractures. DNAPL fracture saturations (Sn) ranged from undetectable to 0.007 (DNAPL volume/fracture volume). A comparison of the fracture flow field to the DNAPL distribution indicated that the highest value of Sn was observed in the least transmissive fracture (or fracture zone). Application of a simple ambient dissolution model showed that the DNAPL present in this low transmissivity zone would persist longer than the DNAPL present in more transmissive fractures and would persist for 200 years (in the absence of any degradation reactions). Assessment of PCE mass distribution between the rock matrix and fractures showed that, due to the presence of DNAPL, the rock matrix accounted for less than 10% of the total PCE mass. The evaluation of PCE concentration profiles in the rock matrix and the estimated diffusional flux from the rock matrix suggest that the elevated PCE groundwater concentrations observed in the fractures likely are due to the presence of the residual DNAPL sources and that removal of the residual DNAPL sources within the fractures would result in a significant decrease in dissolved PCE concentrations in the source area.

  15. Ultrasonic properties of granular media saturated with DNAPL/water mixtures

    NASA Astrophysics Data System (ADS)

    Ajo-Franklin, J. B.; Geller, J. T.; Harris, J. M.

    2007-04-01

    We present the results of four experiments investigating the ultrasonic properties of granular materials partially saturated with trichloroethylene (TCE), a dense non-aqueous contaminant. P-wave velocity measurements were made under in situ effective stress conditions using a pulse transmission cell at ~250 kHz. Two synthetic samples and two natural aquifer cores were fully saturated with water and then subjected to an axial injection of TCE. The resulting measurements show reductions in P-wave velocity of up to 15% due to contaminant saturation. A theoretical model combining Gassmann fluid substitution and Hill's equation was used to estimate the effects of DNAPL saturation; this model underpredicted observed reductions in velocity at high TCE saturations. A linear relationship, expressed in terms of volumetric contaminant fraction, provided an excellent empirical fit to the laboratory measurements.

  16. Hydraulic fracturing to enhance the remediation of DNAPL in low permeability soils

    SciTech Connect

    Murdoch, L.; Slack, B.

    1996-08-01

    Meager rates of fluid flow are a major obstacle to in situ remediation of low permeability soils. This paper describes methods designed to avoid that obstacle by creating fractures and filling them with sand to increase well discharge and change paths of fluid flow in soil. Gently dipping fractures 10 m in maximum dimension and 1 to 2 cm thick can be created in some contaminated soils at depths of a few in or greater. Hydraulic fractures can also be used to create electrically conductive layers or to deliver granules of chemically or biologically active compounds that will degrade contaminants in place. Benefits of applying hydraulic fractures to DNAPL recovery include rates of fluid recovery, enhancing upward gradients to improve hydrodynamic stabilization, forming flat-lying reactive curtains to intersect compounds moving downward, or improving the performance of electrokinetics intended to recover compounds dissolved in water. 30 refs., 7 figs., 1 tab.

  17. Ultrasound assisted, thermally activated persulfate oxidation of coal tar DNAPLs.

    PubMed

    Peng, Libin; Wang, Li; Hu, Xingting; Wu, Peihui; Wang, Xueqing; Huang, Chumei; Wang, Xiangyang; Deng, Dayi

    2016-11-15

    The feasibility of ultrasound assisted, thermally activated persulfate for effective oxidation of twenty 2-6 ringed coal tar PAHs in a biphasic tar/water system and a triphasic tar/soil/water system were investigated and established. The results indicate that ultrasonic assistance, persulfate and elevated reaction temperature are all required to achieve effective oxidation of coal tar PAHs, while the heating needed can be provided by ultrasonic induced heating as well. Further kinetic analysis reveals that the oxidation of individual PAH in the biphasic tar/water system follows the first-order kinetics, and individual PAH oxidation rate is primary determined by the mass transfer coefficients, tar/water interfacial areas, the aqueous solubility of individual PAH and its concentration in coal tar. Based on the kinetic analysis and experimental results, the contributions of ultrasound, persulfate and elevated reaction temperature to PAHs oxidation were characterized, and the effects of ultrasonic intensity and oxidant dosage on PAHs oxidation efficiency were investigated. In addition, the results indicate that individual PAH degradability is closely related to its reactivity as well, and the high reactivity of 4-6 ringed PAHs substantially improves their degradability.

  18. Acidification due to microbial dechlorination near a trichloroethene DNAPL is overcome with pH buffer or formate as electron donor: experimental demonstration in diffusion-cells.

    PubMed

    Philips, Jo; Maes, Nele; Springael, Dirk; Smolders, Erik

    2013-04-01

    Acidification due to microbial dechlorination of trichloroethene (TCE) can limit the bio-enhanced dissolution of TCE dense non-aqueous phase liquid (DNAPL). This study related the dissolution enhancement of a TCE DNAPL to the pH buffer capacity of the medium and the type of electron donor used. In batch systems, dechlorination was optimal at pH7.1-7.5, but was completely inhibited below pH6.2. In addition, dechlorination in batch systems led to a smaller pH decrease at an increasing pH buffer capacity or with the use of formate instead of lactate as electron donor. Subsequently, bio-enhanced TCE DNAPL dissolution was quantified in diffusion-cells with a 5.5 cm central sand layer, separating a TCE DNAPL layer from an aqueous top layer. Three different pH buffer capacities (2.9 mM-17.9 mM MOPS) and lactate or formate as electron donor were applied. In the lactate fed diffusion-cells, the DNAPL dissolution enhancement factor increased from 1.5 to 2.2 with an increase of the pH buffer capacity. In contrast, in the formate fed diffusion-cells, the DNAPL dissolution enhancement factor (2.4±0.3) was unaffected by the pH buffer capacity. Measurement of the pore water pH confirmed that the pH decreased less with an increased pH buffer capacity or with formate instead of lactate as electron donor. These results suggest that the significant impact of acidification on bio-enhanced DNAPL dissolution can be overcome by the amendment of a pH buffer or by applying a non acidifying electron donor like formate. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Seasonal occurrence, removal, mass loading and environmental risk assessment of 55 pharmaceuticals and personal care products in a municipal wastewater treatment plant in Central Greece.

    PubMed

    Papageorgiou, Myrsini; Kosma, Christina; Lambropoulou, Dimitra

    2016-02-01

    A comprehensive study, which contains the seasonal occurrence, removal, mass loading and environmental risk assessment of 55 multi-class pharmaceuticals and personal care products (PPCPs), took place in the wastewater treatment plant (WWTP) of Volos, Greece. A one year monitoring study was performed and the samples were collected from the influent and the effluent of the WWTP. Solid phase extraction was used for the pre-concentration of the samples followed by an LC-DAD-ESI/MS analysis. Positive samples were further confirmed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The maximum concentrations of the PPCPs varied between 21 ng/L and 15,320 ng/L in the influents and between 18 ng/L and 9965 ng/L in the effluents. The most commonly detected PPCPs were the diuretic furosemide, the beta-blockers atenolol and metoprolol, the analgesics paracetamol, nimesulide, salicylic acid and diclofenac and the psychomotor stimulant caffeine. The removal efficiencies ranged between negative and high removal rates, demonstrating that the WWTP is not able to efficiently remove the complex mixture of PPCPs. The estimated mass loads ranged between 5.1 and 3513 mg/day/1000 inhabitants for WWTP influent and between 4.1 to 2141 mg/day/1000 inhabitants for WWTP effluent. Finally, environmental risk assessment has been regarded a necessary part of the general research. According to the results produced from the calculation of the risk quotient on three trophic levels, the anti-inflammatory drug diclofenac and the antibiotics, trimethoprim and ciprofloxacin, identified to be of high potential environmental risk for acute toxicity, while diclofenac also for chronic toxicity. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Demonstration of a Fractured Rock Geophysical Toolbox (FRGT) for Characterization and Monitoring of DNAPL Biodegradation in Fractured Rock Aquifers

    DTIC Science & Technology

    2016-01-01

    USER’S GUIDE Demonstration of a Fractured Rock Geophysical Toolbox (FRGT) for Characterization and Monitoring of DNAPL Biodegradation in... Fractured Rock Aquifers ESTCP Project ER-201118 JANUARY 2016 F.D. Day-Lewis C.D. Johnson U. S. Geological Survey, Office of Groundwater...RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 01/01/2016 Guidance July 2011 - January 2016 Demonstration of a Fractured Rock Geophysical

  1. Degradation of multi-DNAPLs by a UV/persulphate/ethanol system with the additional injection of a base solution.

    PubMed

    Jung, Jae-Gu; Do, Si-Hyun; Kwon, Yong-Jae; Kong, Sung-Ho

    2015-01-01

    This study was conducted to investigate the inhibited influences on and solution to the degradation of four types of dense non-aqueous phase liquids (DNAPLs) (i.e. perchloroethylene [PCE], trichloroethylene [TCE], chloroform [CF], and carbon tetrachloride [CT]) all at the same instance in groundwater (GW). Degradations of DNAPLs in de-ionized water (DW) and GW were carried out by applying an ultraviolet radiation-activated persulphate (UV/PS) system. PCE and TCE were degraded by over 90% and CT was only degraded by 25% in both DW and GW. However, CF was degraded by over 90% in DW, while it was only degraded by 50% in GW. First of all, degradations with an inorganic anion (either Cl- or HCO3-) indicated that the lower degradation of CF in GW was caused by the existence of the chloride ion. Moreover, the low CF degradation in GW was overcome by the additional injection of a base solution (sodium hydroxide [NaOH]) into the UV/PS system. The results showed that PCE, TCE, and CF were degraded by over 90%, respectively, when a molar ratio of [base]0:[PS]0 was larger than 0.5:1, but CT was still not effectively degraded in the UV/PS system. To achieve effective CT degradation, UV/PS with the ethanol (EtOH) system was evaluated and it was found that it degraded CT over 90%. However, at this time, CF was not effectively degraded in the UV/PS/EtOH system. Finally, degradations of DNAPLs in the UV/PS/EtOH system with the additional injection of a base solution were conducted and it showed that multi-DNAPLs were degraded by over 90%, respectively, when the molar ratio of [PS]0:[EtOH]0:[base]0 was 1:1:3.

  2. One-step selective electrokinetic removal of inorganic anions from small volumes and its application as sample clean-up for mass spectrometric techniques.

    PubMed

    Tubaon, Ria Marni; Haddad, Paul R; Quirino, Joselito P

    2017-03-10

    The presence of inorganic anions in a sample interferes with mass spectrometric (MS) analysis. Here, a simple method to remove these ions from a liquid sample in one-step is described. The inorganic anions present in a 50μL sample were extracted into a low pH solution inside a 200μm i.d.×33cm long capillary by the use of an electric field. The selective removal of unwanted anions and retention of target analytes was accomplished by control of the apparent electrophoretic velocities of anions and analytes at a boundary that separated the sample and extraction solution. No physical barrier (e.g., membrane) was required and with the boundary situated at the tip of the capillary, efficient removal of inorganic anions (e.g., >80% removal) and good recovery of target analytes (e.g., >80% recovery) were achieved. The time required for removal of the inorganic anions was found to depend on their initial concentrations. The removal process was investigated using different concentrations of bromide and nitrate (as potassium salts) and negatively chargeable drugs as target analytes. This micro-sample clean-up technique used no organic solvents and little consumables and was studied to the determination of 0.6μg/L arsenic and 8.3μg/L vanadium in 500mg/L sodium chloride using inductively coupled plasma MS and 50μM angiotensin I in 1000mg/L sodium chloride using electrospray ionisation MS. Micro-sample clean-up was performed for 45min at 3kV in both demonstrations. The calculated recoveries for the metals at trace levels were 110-130%, and for the peptide was 103.8%.

  3. NON-INVASIVE DETERMINATION OF THE LOCATION AND DISTRIBUTION OF FREE-PHASE DENSE NONAQUEOUS PHASE LIQUIDS (DNAPL) BY SEISMIC REFLECTION TECHNIQUES

    SciTech Connect

    Michael G. Waddell; William J. Domoracki; Tom J. Temples; Jerome Eyer

    2001-05-01

    The Earth Sciences and Resources Institute, University of South Carolina is conducting a 14 month proof of concept study to determine the location and distribution of subsurface Dense Nonaqueous Phase Liquid (DNAPL) carbon tetrachloride (CCl{sub 4}) contamination at the 216-Z-9 crib, 200 West area, Department of Energy (DOE) Hanford Site, Washington by use of two-dimensional high resolution seismic reflection surveys and borehole geophysical data. The study makes use of recent advances in seismic reflection amplitude versus offset (AVO) technology to directly detect the presence of subsurface DNAPL. The techniques proposed are a noninvasive means towards site characterization and direct free-phase DNAPL detection. This report covers the results of Task 3 and change of scope of Tasks 4-6. Task 1 contains site evaluation and seismic modeling studies. The site evaluation consists of identifying and collecting preexisting geological and geophysical information regarding subsurface structure and the presence and quantity of DNAPL. The seismic modeling studies were undertaken to determine the likelihood that an AVO response exists and its probable manifestation. Task 2 is the design and acquisition of 2-D seismic reflection data designed to image areas of probable high concentration of DNAPL. Task 3 is the processing and interpretation of the 2-D data. Task 4, 5, and 6 were designing, acquiring, processing, and interpretation of a three dimensional seismic survey (3D) at the Z-9 crib area at 200 west area, Hanford.

  4. Sampling results, DNAPL monitoring well GW-790, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee, first-third quarter, FY 1995

    SciTech Connect

    1996-05-01

    In January 1990, dense, non aqueous phase liquids (DNAPLs) were discovered at a depth of approximately 274 ft. below ground surface along the southern border of the Y-12 Plant Burial Grounds. Immediately after the discovery, an investigation was conducted to assess the occurrence of DNAPL at the site and to make recommendations for further action. To date, free-phase DNAPL contamination has been encountered in GW-625 (the discovery well), and is suspected to occur in GW-628 and GW-629. In addition, groundwater from GW-117 shows levels of volatile organic compounds suggestive of a dissolved contaminant plume. Results of the preliminary DNAPL investigation are presented in detail, and a work plan for assessment and characterization of the DNAPL is presented. A major task in the work plan calls for the construction and installation of five multipart wells. These wells (GW-726, GW-727, GW-729, GW-730, GW-730 and GW- 790) were constructed and instrumented with multipart components from August, 1991 to April, 1993. Subsequently, purging and sampling activities were started in each well. This report summarizes purging and sampling activities for GW-790 and presents analytical results for GW-790.

  5. Challenges for simultaneous nitrification, denitrification, and phosphorus removal in microbial aggregates: mass transfer limitation and nitrous oxide production.

    PubMed

    Meyer, Rikke Louise; Zeng, Raymond Jianxiong; Giugliano, Valerio; Blackall, Linda Louise

    2005-05-01

    The microbial community composition and activity was investigated in aggregates from a lab-scale bioreactor, in which nitrification, denitrification and phosphorus removal occurred simultaneously. The biomass was highly enriched for polyphosphate accumulating organisms facilitating complete removal of phosphorus from the bulk liquid; however, some inorganic nitrogen still remained at the end of the reactor cycle. This was ascribed to incomplete coupling of nitrification and denitrification causing NO(3)(-) accumulation. After 2 h of aeration, denitrification was dependent on the activity of nitrifying bacteria facilitating the formation of anoxic zones in the aggregates; hence, denitrification could not occur without simultaneous nitrification towards the end of the reactor cycle. Nitrous oxide was identified as a product of denitrification, when based on stored PHA as carbon source. This observation is of critical importance to the outlook of applying PHA-driven denitrification in activated sludge processes.

  6. Mass transfer study on the electrochemical removal of copper ions from synthetic effluents using reticulated vitreous carbon.

    PubMed

    Britto-Costa, Pedro H; Ruotolo, Luís Augusto M

    2013-01-01

    Porous electrodes have been successfully used for metal electrodeposition from diluted aqueous solution due to their high porosity and specific surface area, which lead to high mass transfer rates. This work studies the mass transfer of copper electrodeposition on reticulated vitreous carbon in a flow reactor without membrane. The flow configuration, otherwise the filter-press electrochemical reactors, was designed in order to minimize the pressure drop. The mass transfer coefficient was determined by voltammetric and galvanostatic electrodeposition. In the voltammetric experiments a Luggin capillary was used to measure the current-potential curves and to determine the limiting current (and, consequently, the mass transfer coefficient). In the galvanostatic experiments the concentration-time curves were obtained and considering a limiting current kinetics model, the mass transfer coefficient (k(m)) was determined for different flow velocities. The results showed that both methods give similar values of k(m), thus the voltammetric method can be recommended because it is faster and simpler. Finally, the reactor performance was compared with others from literature, and it was observed that the proposed reactor design has high Sherwood numbers similar to other reactor configurations using membranes and reticulated vitreous carbon electrodes.

  7. Mapping Contaminant Remediation with Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Gerhard, J.; Power, C.; Tsourlos, P.; Karaoulis, M.; Giannopoulos, A.; Soupios, P. M.; Simyrdanis, K.

    2014-12-01

    The remediation of sites contaminated with industrial chemicals - specifically dense non-aqueous phase liquids (DNAPLs) like coal tar and chlorinated solvents - represents a major geoenvironmental challenge. Remediation activities would benefit from a non-destructive technique to map the evolution of DNAPL mass in space and time. Electrical resistivity tomography (ERT) has long-standing potential in this context but has not yet become a common tool at DNAPL sites. This work evaluated the potential of time-lapse ERT for mapping DNAPL mass reduction in real time during remediation. Initially, a coupled DNAPL-ERT numerical model was developed for exploring this potential at the field scale, generating realistic DNAPL scenarios and predicting the response of an ERT survey. Also, new four-dimensional (4D) inversion algorithms were integrated for tracking DNAPL removal over time. 4D ERT applied at the surface for mapping an evolving DNAPL distribution was first demonstrated in a laboratory experiment. Independent simulation of the experiment demonstrated the reliability of the DNAPL-ERT model for simulating real systems. The model was then used to explore the 4D ERT approach at the field scale for a range of realistic DNAPL remediation scenarios. The approach showed excellent potential for mapping shallow DNAPL changes. However, remediation at depth was not as well resolved. To overcome this limitation, a new surface-to-horizontal borehole (S2HB) ERT configuration is proposed. A second laboratory experiment was conducted that demonstrated that S2HB ERT does better resolve changes in DNAPL distribution relative to surface ERT, particularly at depth. The DNAPL-ERT model was also used to demonstrate the improved mapping of S2HB ERT for field scale DNAPL scenarios. Overall, this work demonstrates that, with these innovations, ERT exhibits significant potential as a real time, non-destructive geoenvironmental remediation site monitoring tool.

  8. Seasonal and spatial variations of PPCP occurrence, removal and mass loading in three wastewater treatment plants located in different urbanization areas in Xiamen, China.

    PubMed

    Sun, Qian; Li, Mingyue; Ma, Cong; Chen, Xiangqiang; Xie, Xiaoqing; Yu, Chang-Ping

    2016-01-01

    The occurrence and fate of 48 pharmaceuticals and personal care products (PPCPs) in three wastewater treatment plants (WWTPs) located in different urbanization areas in Xiamen, China was investigated over one year. Results showed that PPCPs were widely detected, but the major PPCPs in the influent, effluent, and sludge were different. Spatial and seasonal variations of PPCP levels in the influent and sludge were observed. The removal efficiencies for most PPCPs were similar among the three WWTPs, although they employed different biological treatment processes. Furthermore, the mass loadings per inhabitant of most pharmaceuticals had a positive correlation with the urbanization levels, indicating that most pharmaceutical usage was higher in the urban core compared to the suburban zones. The total mass loadings of all the 48 PPCPs in the effluent and waste sludge showed close proportions, which suggested the importance of proper waste sludge disposal to prevent a large quantity of PPCPs from entering the environment.

  9. Influence of Mass Transfer Kinetics on Interpretation of Push-Pull Partitioning Tracer Tests

    NASA Astrophysics Data System (ADS)

    Ervin, R. E.; Boroumand, A.; Abriola, L. M.; Ramsburg, C. A.

    2012-12-01

    model containing a linear driving force expression to describe the tracer mass transfer. Mass transfer coefficients in all simulations were produced using available correlations for pool dissolution. Perfect knowledge of the DNAPL and permeability distributions, as well as relative permeability effects enabled the numerical model to better capture the asymmetry observed in the production curves. We then began to systematically simplify the numerical model to explore which assumptions associated with the analytical solution cause its poor performance. These assumptions include: uniform packing distribution, uniform DNAPL distribution, equilibrium partitioning, and no permeability reduction due to the presence of the DNAPL. Results suggest only limited degradation in model performance when the medium permeability and DNAPL saturation are assumed to be uniform, and relative permeability effects are neglected. In contrast, model performance was considerably poorer when mass transfer kinetics were neglected. These results highlight the importance of including mass transfer kinetics when characterizing local-scale DNAPL architecture.

  10. Validation and Application of the Mass Balance Model To Determine the Effectiveness of Portable Air Purifiers in Removing Ultrafine and Submicrometer Particles in an Apartment.

    PubMed

    Lee, Wan-Chen; Catalano, Paul J; Yoo, Jun Young; Park, Chan Jung; Koutrakis, Petros

    2015-08-18

    We validated the use of the mass balance model to determine the effectiveness of portable air purifiers in removing ultrafine (<0.10 μm) and submicrometer particles (0.10-0.53 μm) in an apartment. We evaluated two identical portable air purifiers, equipped with high efficiency particulate air filters, for their performance under three different air flow settings and three target air exchange rates: 0.60, 0.90, and 1.20 h(-1). We subsequently used a mixed effects model to estimate the slope between the measured and modeled effectiveness by particle size. Our study showed that effectiveness was highly particle size-dependent. For example, at the lowest target air exchange rate, it ranged from 0.33 to 0.56, 0.51 to 0.75, and 0.60 to 0.81 for the three air purifier flow settings, respectively. Our findings suggested that filtration was the dominant removal mechanism for submicrometer particles, whereas deposition could play a more important role in ultrafine particle removal. We found reasonable agreement between measured and modeled effectiveness with size-resolved slopes ranging from 1.11 ± 0.06 to 1.25 ± 0.07 (mean ± SE), except for particles <35 nm. Our study design can be applied to investigate the performances of other portable air purifiers as well as the influences of various parameters on effectiveness in different residential settings.

  11. Force analysis and visualization of NAPL removal during surfactant-related floods in a porous medium.

    PubMed

    Jeong, Seung-Woo; Corapcioglu, M Yavuz

    2005-11-11

    Governing mechanisms of dense non-aqueous phase liquid (DNAPL) removal during surfactant and surfactant-foam (SF) flooding were studied by porous-patterned glass model experiments. Physical forces, viscous forces and capillary forces, acting on trichloroethylene (TCE) blobs were quantified to understand DNAPL removal mechanisms during the floods, simultaneously visualizing the removal mechanisms. The viscous force of the remedial fluid was intimately related to TCE removal from the porous medium. The remedial fluid with a high viscous force displaced more TCE blobs. Displacement of residual TCE by the remedial fluid began as viscous pressure of flooding was closed to the capillary pressure of the porous medium. In the region of viscous pressure less than the capillary pressure, residual TCE was either retained or solubilized, not displaced, implying that TCE solubilization was the dominant TCE removal process. Glass porous model visualization validated a dominance of the capillary forces during a surfactant flush and a dominance of the viscous forces of the displacing fluid during a SF flood.

  12. Performance evaluation of different horizontal subsurface flow wetland types by characterization of flow behavior, mass removal and depth-dependent contaminant load.

    PubMed

    Seeger, Eva M; Maier, Uli; Grathwohl, Peter; Kuschk, Peter; Kaestner, Matthias

    2013-02-01

    For several pilot-scale constructed wetlands (CWs: a planted and unplanted gravel filter) and a hydroponic plant root mat (operating at two water levels), used for treating groundwater contaminated with BTEX, the fuel additive MTBE and ammonium, the hydrodynamic behavior was evaluated by means of temporal moment analysis of outlet tracer breakthrough curves (BTCs): hydraulic indices were related to contaminant mass removal. Detailed investigation of flow within the model gravel CWs allowed estimation of local flow rates and contaminant loads within the CWs. Best hydraulics were observed for the planted gravel filter (number of continuously stirred tank reactors N = 11.3, dispersion number = 0.04, Péclet number = 23). The hydroponic plant root mat revealed lower N and pronounced dispersion tendencies, whereby an elevated water table considerably impaired flow characteristics and treatment efficiencies. Highest mass removals were achieved by the plant root mat at low level: 98% (544 mg m⁻² d⁻¹), 78% (54 mg m⁻² d⁻¹) and 74% (893 mg m⁻² d⁻¹) for benzene, MTBE and ammonium-nitrogen, respectively. Within the CWs the flow behavior was depth-dependent, with the planting and the position of the outlet tube being key factors resulting in elevated flow rate and contaminant flux immediately below the densely rooted porous media zone in the planted CW, and fast bottom flow in the unplanted reference. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Evaluating DNAPL Source and Migration Zones: M-Area Settling Basin and the Western Sector of A/M Area, Savannah River Site

    SciTech Connect

    Jackson, D.G.

    2001-09-11

    The objective of this investigation is to critically evaluate previous characterization and remediation data to determine the current extent and distribution of DNAPL associated with releases at the M-Area Basin within A/M Area. The primary objective of the effort is to develop an approximate recommendation for the target treatment location and volume near the M Area Settling Basin. Through this analysis the final objective is to identify those subsurface regions having specific geometry and character necessary to cost-effectively deploy DNAPL specific remediation alternatives.

  14. Nitrogen removal and mass balance in newly-formed Myriophyllum aquaticum mesocosm during a single 28-day incubation with swine wastewater treatment.

    PubMed

    Liu, Feng; Zhang, Shunan; Wang, Yi; Li, Yong; Xiao, Runlin; Li, Hongfang; He, Yang; Zhang, Miaomiao; Wang, Di; Li, Xi; Wu, Jinshui

    2016-01-15

    The aim of this research was to assess the applicability of Myriophyllum (M.) aquaticum for swine wastewater treatment. Nitrogen (N) removal processes were investigated in M. aquaticum mesocosms with swine wastewater (SW), 50% diluted swine wastewater (50% SW), and two strengths of synthetic wastewater, 200 mg [Formula: see text] L(-1) (200 [Formula: see text] ) and 400 mg [Formula: see text] L(-1) (400 [Formula: see text] ). During a 28-day incubation period, the average [Formula: see text] and TN removal rates were 99.8% and 94.2% for 50% SW and 99.8% and 93.8% for SW, which were greater than 86.5% and 83.7% for 200 [Formula: see text] , and 73.7% and 74.1% for 400 [Formula: see text] , respectively. A maximum areal total nitrogen (TN) removal rate of 157.8 mg N m(-2) d(-1) was found in M. aquaticum mesocosms with SW. During the incubation period, the observed dynamics of [Formula: see text] concentrations in water and gene copy numbers of ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), nirK and nirS in soil unraveled strong nitrification and denitrification processes occurring in M. aquaticum mesocosms with swine wastewater. The N mass balance analysis indicated that plant uptake and soil N accumulation accounted for 17.9-42.2% and 18.0-43.8% of the initial TN load, respectively. The coupled nitrification and denitrification process was calculated to account for, on average, 36.8% and 62.8% of TN removal for 50% SW and SW, respectively. These findings demonstrated that the N uptake by M. aquaticum contributed to a considerable proportion of N removal. In particular, the activities of ammonia-oxidizing and denitrification microbes responsible for nitrification and denitrification processes in M. aquaticum mesocosm accelerated [Formula: see text] and TN removal from swine wastewater.

  15. Long-term observations of black carbon mass concentrations at Fukue Island, western Japan, during 2009-2015: constraining wet removal rates and emission strengths from East Asia

    NASA Astrophysics Data System (ADS)

    Kanaya, Yugo; Pan, Xiaole; Miyakawa, Takuma; Komazaki, Yuichi; Taketani, Fumikazu; Uno, Itsushi; Kondo, Yutaka

    2016-08-01

    Long-term (2009-2015) observations of atmospheric black carbon (BC) mass concentrations were performed using a continuous soot-monitoring system (COSMOS) at Fukue Island, western Japan, to provide information on wet removal rate constraints and the emission strengths of important source regions in East Asia (China and others). The annual average mass concentration was 0.36 µg m-3, with distinct seasonality; high concentrations were recorded during autumn, winter, and spring and were caused by Asian continental outflows, which reached Fukue Island in 6-46 h. The observed data were categorized into two classes, i.e., with and without a wet removal effect, using the accumulated precipitation along a backward trajectory (APT) for the last 3 days as an index. Statistical analysis of the observed ΔBC / ΔCO ratios was performed to obtain information on the emission ratios (from data with zero APT only) and wet removal rates (including data with nonzero APTs). The estimated emission ratios (5.2-6.9 ng m-3 ppb-1) varied over the six air mass origin areas; the higher ratios for south-central East China (30-35° N) than for north-central East China (35-40° N) indicated the relative importance of domestic emissions and/or biomass burning sectors. The significantly higher BC / CO emission ratios adopted in the bottom-up Regional Emission inventory in Asia (REAS) version 2 (8.3-23 ng m-3 ppb-1) over central East China and Korea needed to be reduced at least by factors of 1.3 and 2.8 for central East China and Korea, respectively, but the ratio for Japan was reasonable. The wintertime enhancement of the BC emission from China, predicted by REAS2, was verified for air masses from south-central East China but not for those from north-central East China. Wet removal of BC was clearly identified as a decrease in the ΔBC / ΔCO ratio against APT. The transport efficiency (TE), defined as the ratio of the ΔBC / ΔCO ratio with precipitation to that without precipitation, was

  16. Hydrogeophysical imaging of deposit heterogeneity and groundwater chemistry changes during DNAPL source zone bioremediation

    NASA Astrophysics Data System (ADS)

    Chambers, J. E.; Wilkinson, P. B.; Wealthall, G. P.; Loke, M. H.; Dearden, R.; Wilson, R.; Allen, D.; Ogilvy, R. D.

    2010-10-01

    Robust characterization and monitoring of dense nonaqueous phase liquid (DNAPL) source zones is essential for designing effective remediation strategies, and for assessing the efficacy of treatment. In this study high-resolution cross-hole electrical resistivity tomography (ERT) was evaluated as a means of monitoring a field-scale in-situ bioremediation experiment, in which emulsified vegetable oil (EVO) electron donor was injected into a trichloroethene source zone. Baseline ERT scans delineated the geometry of the interface between the contaminated alluvial aquifer and the underlying mudstone bedrock, and also the extent of drilling-induced physical heterogeneity. Time-lapse ERT images revealed major preferential flow pathways in the source and plume zones, which were corroborated by multiple lines of evidence, including geochemical monitoring and hydraulic testing using high density multilevel sampler arrays within the geophysical imaging planes. These pathways were shown to control the spatial distribution of the injected EVO, and a bicarbonate buffer introduced into the cell for pH control. Resistivity signatures were observed within the preferential flow pathways that were consistent with elevated chloride levels, providing tentative evidence from ERT of the biodegradation of chlorinated solvents.

  17. Permanganate treatment of DNAPLs in reactive barriers and source zone flooding schemes. 1997 annual progress report

    SciTech Connect

    Schwartz, F.W.

    1997-01-01

    'The goals of this study are (1) to elucidate the basic mechanisms by which potassium permanganate oxidizes common chlorinated solvents, various constituents in aqueous solution, and porous-medium solids, and (2) to assess the potential for chemical oxidation by potassium permanganate to serve as a remedial scheme involving either source zone flooding or reactive barriers. The research plan involves a combined experimental/modeling study that builds on the extensive previous work in the area of reactive barrier systems, and modeling of reactive contaminant transport. The experimental studies are being undertaken at The Ohio State University by Dr. Schwartz and his co-workers. The modeling work is being conducted in Albuquerque, NM by Dr. Zhang of Intera, Inc. The workplan for this study is designed around the following four objectives (1) to describe through batch experiments the kinetics and mechanisms by which potassium permanganate oxidizes dissolved tetrachloroethene (PCE), trichloroethene (TCE), and dichloroethene (DCE), (2) to examine using column studies the nature and kinetics of reactions between potassium permanganate, residual DNAPLs (PCE, TCE, and DCE) and porous medium solids, (3) to represent the process understanding in flow and transport models that demonstrate the potential applicability of the approach, and (4) to apply the resulting computer code in the development of appropriate field tests for assessing the approach.'

  18. Hydrogeophysical imaging of deposit heterogeneity and groundwater chemistry changes during DNAPL source zone bioremediation.

    PubMed

    Chambers, J E; Wilkinson, P B; Wealthall, G P; Loke, M H; Dearden, R; Wilson, R; Allen, D; Ogilvy, R D

    2010-10-21

    Robust characterization and monitoring of dense nonaqueous phase liquid (DNAPL) source zones is essential for designing effective remediation strategies, and for assessing the efficacy of treatment. In this study high-resolution cross-hole electrical resistivity tomography (ERT) was evaluated as a means of monitoring a field-scale in-situ bioremediation experiment, in which emulsified vegetable oil (EVO) electron donor was injected into a trichloroethene source zone. Baseline ERT scans delineated the geometry of the interface between the contaminated alluvial aquifer and the underlying mudstone bedrock, and also the extent of drilling-induced physical heterogeneity. Time-lapse ERT images revealed major preferential flow pathways in the source and plume zones, which were corroborated by multiple lines of evidence, including geochemical monitoring and hydraulic testing using high density multilevel sampler arrays within the geophysical imaging planes. These pathways were shown to control the spatial distribution of the injected EVO, and a bicarbonate buffer introduced into the cell for pH control. Resistivity signatures were observed within the preferential flow pathways that were consistent with elevated chloride levels, providing tentative evidence from ERT of the biodegradation of chlorinated solvents.

  19. Remediation of DNAPLs in Low Permeability Soils. Innovative Technology Summary Report

    SciTech Connect

    2000-09-01

    Dense, non-aqueous phase liquid (DNAPL) compounds like trichloroethene (TCE) and perchloroethene (PCE) are prevalent at U. S. Department of Energy (DOE), other government, and industrial sites. Their widespread presence in low permeability media (LPM) poses severe challenges for assessment of their behavior and implementation of effective remediation technologies. Most remedial methods that involve fluid flow perform poorly in LPM. Hydraulic fracturing can improve the performance of remediation methods such as vapor extraction, free-product recovery, soil flushing, steam stripping, bioremediation, bioventing, and air sparging in LPM by enhancing formation permeability through the creation of fractures filled with high-permeability materials, such as sand. Hydraulic fracturing can improve the performance of other remediation methods such as oxidation, reductive dechlorination, and bioaugmentation by enhancing delivery of reactive agents to the subsurface. Hydraulic fractures are typically created using a 2-in. steel casing and a drive point pushed into the subsurface by a pneumatic hammer. Hydraulic fracturing has been widely used for more than 50 years to stimulate the yield of wells recovering oil from rock at great depth and has recently been shown to stimulate the yield of wells recovering contaminated liquids and vapors from LPM at shallow depths. Hydraulic fracturing is an enabling technology for improving the performance of some remedial methods and is a key element in the implementation of other methods. This document contains information on the above-mentioned technology, including description, applicability, cost, and performance data.

  20. Field demonstration of surfactant-enhanced solubilization of DNAPL at Dover Air Force Base, Delaware

    NASA Astrophysics Data System (ADS)

    Childs, Jeffrey; Acosta, Edgar; Annable, Michael D.; Brooks, Michael C.; Enfield, Carl G.; Harwell, Jeffrey H.; Hasegawa, Mark; Knox, Robert C.; Rao, P. Suresh C.; Sabatini, David A.; Shiau, Ben; Szekeres, Erika; Wood, A. Lynn

    2006-01-01

    This study reports on a surfactant-based flood for tetrachloroethylene (PCE) removal from a control test cell at the Dover National Test Site. The surfactant formulation (sodium dihexyl sulfosuccinate (Aerosol-MA® or AMA), isopropanol and calcium chloride) was able to achieve a high concentration of PCE in swollen micelles (supersolubilization) without vertical PCE migration. The hydraulic system included eight screened wells that were operated in both vertical circulation and line drive configurations. After 10 pore volumes of flushing, the overall PCE removal was 68% (65% of which corresponded to the surfactant flooding alone). In addition, the residual PCE saturation was reduced from 0.7% to 0.2%, and the concentration of PCE in the groundwater was reduced from 37-190 mg/L before the flushing to 7.3 mg/L after flooding. Recycling the surfactant solution reduced the required surfactant mass (and thus cost, and waste) by 90%. Close to 80% of the total PCE removal was obtained during the first five pore volumes which were operated in an upward vertical circulation flow scheme. No free oil phase was observed during the test. Further analysis of multilevel sampler data suggests that most of the trapped oil remaining in the cell was likely localized in secluded regions of the aquifer, which helps explain the lower PCE groundwater concentration after remedial activities. In summary, this field study demonstrated the feasibility of surfactant-enhanced remediation to reduce the mass in the source zone and significantly reduce the PCE aqueous concentration and therefore the risk associated with the contaminant plume.

  1. Testing of Performance of a Scroll Pump in Support of Improved Vapor Phase Catalytic Ammonia Removal (VPCAR) Mass Reduction

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.; Kraft, Thomas G.; Yee, Glenda F.; Jankovsky, Amy L.; Flynn, Michael

    2006-01-01

    This paper describes the results of ground testing of a scroll pump with a potential of being a substitute for the current vacuum pump of the Vapor Phase Catalytic Ammonia Reduction (VPCAR). Assessments of the pressure-time, pump-down time, pump power and the pump noise were made for three configurations of the pump the first of which was without the gas ballast, the second with the gas ballast installed but not operating and the third with the gas ballast operating. The tested scroll pump exhibited optimum characteristics given its mass and power requirements. The pump down time required to reach a pressure of 50 Torr ranged from 60 minutes without the ballast to about 120 minutes with the gas ballast operational. The noise emission and the pump power were assessed in this paper as well.

  2. Testing of Performance of a Scroll Pump in Support of Improved Vapor Phase Catalytic Ammonia Removal (VPCAR) Mass Reduction

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.; Kraft, Thomas G.; Yee, Glenda F.; Jankovsky, Amy L.; Flynn, Michael

    2006-01-01

    This paper describes the results of ground testing of a scroll pump with a potential of being a substitute for the current vacuum pump of the Vapor Phase Catalytic Ammonia Reduction (VPCAR). Assessments of the pressure-time, pump-down time, pump power and the pump noise were made for three configurations of the pump the first of which was without the gas ballast, the second with the gas ballast installed but not operating and the third with the gas ballast operating. The tested scroll pump exhibited optimum characteristics given its mass and power requirements. The pump down time required to reach a pressure of 50 Torr ranged from 60 minutes without the ballast to about 120 minutes with the gas ballast operational. The noise emission and the pump power were assessed in this paper as well.

  3. Sorption of nonionic surfactant oligomers to sediment and PCE DNAPL: Effects on PCE distribution between water and sediment

    SciTech Connect

    John, W.W.; Bao, G.; Johnson, W.P.; Stauffer, T.B.

    2000-02-15

    Introduction of surfactant mixtures to the subsurface for the purpose of surfactant-enhanced aquifer remediation requires consideration of the effects of surfactant sorption to sediment and nonaqueous phase liquids. These effects include alteration of the solubilizing properties of the surfactant mixture and alteration of the sorption properties of the stationary phase. Sorption of octylphenol ethoxylate (EO) surfactant oligomers to a low organic carbon content (f{sub oc}) aquifer sediment and to dense nonaqueous phase liquid (DNAPL) consisting of tetrachloroethene (PCE) was examined in batch experiments. At aqueous surfactant concentrations far below the critical micelle concentration (CMC) of the mixture, sorption to sediment was characterized by an initial steep isotherm for both high and low EO content oligomers, with somewhat greater uptake of high EO content oligomers. This stage of sorption resulted in mild increases in the equilibrium constant, k{sub d,PCEr} for distribution of PCE between solution (including surfactant) and sediment (including sorbed surfactant). As the aqueous surfactant concentration increased, surface aggregation of low EO content oligomers on the sediment commenced, and a dramatic increase in K{sub d,PCE} was observed. At aqueous surfactant concentrations increasing above the CMC, the formation of solution micelles caused the sorbed surfactant concentrations to plateau and then decrease. This decrease in sorbed surfactant, along with competition by micelles for contaminant, likely contributed to the observed rapid decrease in K{sub d,PCE} toward zero. Surfactant sorption to PCE DNAPL was greater relative to sediment by 1--2 orders of magnitude, with much greater uptake of the low EO content oligomers. Sorption of all but the lowest EO content oligomers to the PCE DNAPL was terminated by micellization.

  4. A study on unsaturated zone characterization and feasibility of soil vapor extraction at a DNAPL-contaminated site in Korea

    NASA Astrophysics Data System (ADS)

    Lee, Man Na Mi; Yeo, In Wook

    2013-04-01

    Groundwater contamination by Dense Non-Aqueous Phase Liquids (DNAPLs), such as trichloroethylene (TCE), have been found in many industrial complexes, which is one of the most pressing problems in contaminant hydrology. As DNAPL is denser than water, it migrates downward through the overlying sediments and water table, and there, it forms a long term source of contamination due to its low solubility in water. DNAPL research site, located in Wonju, Republic of Korea, is contaminated with TCE (trichloroethylene), which was used as solvent from 1988 to 1997, and contaminated top soil dug out up to 3 m deep in 2004 to 2005. However, a high concentration (15 mg/L) of TCE in groundwater exceeding drinking water standard (0.03 mg/L in Korea) is still detected in the source zone area. Recent studies showed that the rise in water table led to an increase in TCE concentration, indicating that TCE sources existed in unsaturated zone above/around the water table. Therefore, the purpose of this study aims to characterize unsaturated zone in terms of air permeability and flow connectivity between the boreholes penetrating unsaturated zone, which will consequently be used for the design of pilot scale soil vapor extraction (SVE) system. Five boreholes with three multi-level screens at the depth of 3.0 to 4.5 m, 5.5 to 7.0, and 8.0 to 12.0 m were installed at the source zone for field tests. Pneumatic tests were performed to determine the air permeability. The average air permeability was measured to be 2.18×10-6 cm2. Pressure-drawdown curve well matched leaky aquifer type, indicating that air leaks through the ground surface. Air flow tests were also carried out to investigate air flow connectivity between multi-level wells. When injecting air through the upper level of the well, vertical air flow toward the surface mainly took place with horizontal flow limited. On the other hand, when injecting air to the lower part, the horizontal air flow was well made through unsaturated

  5. Simultaneous detection of perchlorate and bromate using rapid high-performance ion exchange chromatography-tandem mass spectrometry and perchlorate removal in drinking water.

    PubMed

    West, Danielle M; Mu, Ruipu; Gamagedara, Sanjeewa; Ma, Yinfa; Adams, Craig; Eichholz, Todd; Burken, Joel G; Shi, Honglan

    2015-06-01

    Perchlorate and bromate occurrence in drinking water causes health concerns due to their effects on thyroid function and carcinogenicity, respectively. The purpose of this study was threefold: (1) to advance a sensitive method for simultaneous rapid detection of perchlorate and bromate in drinking water system, (2) to systematically study the occurrence of these two contaminants in Missouri drinking water treatment systems, and (3) to examine effective sorbents for minimizing perchlorate in drinking water. A rapid high-performance ion exchange chromatography-tandem mass spectrometry (HPIC-MS/MS) method was advanced for simultaneous detection of perchlorate and bromate in drinking water. The HPIC-MS/MS method was rapid, required no preconcentration of the water samples, and had detection limits for perchlorate and bromate of 0.04 and 0.01 μg/L, respectively. The method was applied to determine perchlorate and bromate concentrations in total of 23 selected Missouri drinking water treatment systems during differing seasons. The water systems selected include different source waters: groundwater, lake water, river water, and groundwater influenced by surface water. The concentrations of perchlorate and bromate were lower than or near to method detection limits in most of the drinking water samples monitored. The removal of perchlorate by various adsorbents was studied. A cationic organoclay (TC-99) exhibited effective removal of perchlorate from drinking water matrices.

  6. Mass loading and removal of pharmaceuticals and personal care products including psychoactives, antihypertensives, and antibiotics in two sewage treatment plants in southern India.

    PubMed

    Subedi, Bikram; Balakrishna, Keshava; Joshua, Derrick Ian; Kannan, Kurunthachalam

    2017-01-01

    Environmental contamination by pharmaceuticals and personal care products (PPCPs) is barely studied in India despite being one of the largest global producers and consumers of pharmaceuticals. In this study, 29 pharmaceuticals and six metabolites were determined in sewage treatment plants (STPs) in Udupi (STPU: population served ∼150,000) and Mangalore (STPM: population served ∼450,000); the measured mean concentrations ranged from 12 to 61,000 ng/L and 5.0 to 31,000 ng/L, respectively. Atorvastatin (the most prescribed antihypercholesterolemic in India), mefenamic acid, and paraxanthine were found for the first time in wastewater in India at the mean concentrations of 395 ng/L, 1100 ng/L, and 13,000 ng/L, respectively. Select pharmaceutical metabolites (norverapamil and clopidogrel carboxylic acid) were found at concentrations of upto 7 times higher than their parent drugs in wastewater influent and effluent. This is the first study in India to report mass loading and emission of PPCPs and their select metabolites in STPs. The total mass load of all PPCPs analyzed in this study at STPU (4.97 g/d/1000 inhabitants) was 3.6 times higher than calculated for STPM. Select recalcitrant PPCPs (carbamazepine, diazepam, and clopidogrel) were found to have negative or no removal from STPU while additional treatment with upflow anaerobic sludge blanket reactor at STPM removed (up to 95%) these PPCPs from STPM. Overall, 5.1 kg of caffeine, 4.1 kg of atenolol, 2.7 kg of ibuprofen, and 1.9 kg of triclocarban were discharged annually from STPU. The PPCP contamination profile in the Indian STP was compared with a similar study in the USA. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Phased Implementation of In Situ Chemical Oxidation for a Large TCE DNAPL Source Area at the Portsmouth Gaseous Diffusion Plant, USA

    SciTech Connect

    Cross, Paul E.

    2007-07-01

    This paper describes the In Situ Chemical Oxidation (ISCO) remediation being implemented for the X-701B groundwater plume at the Department of Energy (DOE) Portsmouth Gaseous Diffusion Plant (PORTS). Modified Fenton's reagent is the principal oxidant for the remedy, and Direct Push Technology (DPT) is being used for delivery of the oxidant. Trichloroethene (TCE) is the primary contaminant of concern and is present within the unit as a dense non - aqueous phase liquid (DNAPL). A phased approach is being implemented to optimize the type, location, and mass of the oxidant injections. During Phase I, a unique near-real time monitoring approach was utilized to observe the transient effects of the oxidant injections on the formation. As a result of the positive results from Phase I, Ohio EPA has approved the final work plan for the remedy, and the approach is now being applied to the source area of the plume. The results from Phase I and the layout for the first series of Phase II injections are presented in this paper. Previous testing at the site has shown that the shallow, water-bearing formation is primarily composed of silty gravel and clay, and is both heterogeneous and anisotropic. These factors have significantly compromised earlier attempts to remediate the unit. A patented ISCO process from In-Situ Oxidative Technologies, Inc. (ISOTEC) was selected for the remediation of the plume. Phase I results indicate that oxidant delivery via DPT is feasible for the unit. Contaminant reduction to date has been minimal due to the small quantity of oxidant injected during Phase I. Contaminant rebound in the aqueous phase remains a concern and will be monitored closely during the remedy. (author)

  8. Monitoring genetic and metabolic potential for in situ bioremediation: Mass spectrometry. 1997 annual progress report

    SciTech Connect

    Buchanan, M.V.; Hurst, G.B.; Britt, P.F.; McLuckey, S.A.; Doktycz, M.J.

    1997-09-01

    'A number of US Department of Energy (DOE) sites are contaminated with mixtures of dense non-aqueous phase liquids (DNAPLs) such as carbon tetrachloride, chloroform,. perchloroethylene, and trichloroethylene. At many of these sites, in situ microbial bioremediation is an attractive strategy for cleanup because it has the potential to degrade DNAPLs in situ without producing toxic byproducts. A rapid screening method to determine the broad range metabolic and genetic potential for contaminant degradation would greatly reduce the cost and time involved in assessment for in situ bioremediation as well as for monitoring ongoing bioremediation treatment. In this project, the ORNL Organic Mass Spectrometry (OMS) group is developing mass-spectrometry-based methods to screen for the genetic and metabolic potential for assessment and monitoring of in situ bioremediation of DNAPLs. In close collaboration, Professor Mary Lidstrom''s group at the University of Washington is identifying short DNA sequences related to microbial processes involved in the biodegradation of pollutants. This work will lay the foundation for development of a field-portable mass-spectrometry-based technique for rapid assessment and monitoring of bioremediation processes on site.'

  9. DEMONSTRATION OF IN SITU DEHALOGENATION OF DNAPL THROUGH INJECTION OF EMULSIFIED ZERO-VALIENT IRON AT LAUNCH COMPLEX 34 IN CAPE CANAVERAL AIR FORCE STATION, FLORIDA

    EPA Science Inventory

    The purpose of this project was to evaluate the technical and cost performance of emulsified zero-valent iron (EZVI) technology when applied to DNAPL contaminants in the saturated zone. This demonstration was conducted at Launch Complex 34, Cape Canaveral Air Force Station, FL, w...

  10. Demonstration of Resistive Heating Treatment of DNAPL Source Zone at Launch Complex 34 in Cape Canaveral Air Force Station, Florida, Final Innovative Technology Evaluation Report

    EPA Science Inventory

    The Interagency DNAPL Consortium (IDC) was formally established in 1999 by the U.S. Department of Energy, U.S. Environmental Protection Agency, the U.S. Department of Defense, and the National Aeronautics and Space Administration. The IDC performed five remediation techniques: ...

  11. Demonstration of Steam Injection/Extraction Treatment of a DNAPL Source Zone at Launch Complex 34 in Cape Canaveral Air Force Station, Final Innovative Technology Evaluation Report

    EPA Science Inventory

    The Interagency DNAPL Consortium (IDC) was formally established in 1999 by the U.S. Department of Energy, U.S. Environmental Protection Agency, the U.S. Department of Defense, and the National Aeronautics and Space Administration. The IDC performed five remediation techniques: ...

  12. Demonstration of Steam Injection/Extraction Treatment of a DNAPL Source Zone at Launch Complex 34 in Cape Canaveral Air Force Station, Final Innovative Technology Evaluation Report

    EPA Science Inventory

    The Interagency DNAPL Consortium (IDC) was formally established in 1999 by the U.S. Department of Energy, U.S. Environmental Protection Agency, the U.S. Department of Defense, and the National Aeronautics and Space Administration. The IDC performed five remediation techniques: ...

  13. THE VELOCITY OF DNAPL FINGERING IN WATER-SATURATED POROUS MEDIA LABORATORY EXPERIMENTS AND A MOBILE-IMMOBILE-ZONE MODEL. (R826157)

    EPA Science Inventory

    Dense nonaqueous phase liquids (DNAPLs) are immiscible with water and can give rise to highly fingered fluid distributions when infiltrating through water-saturated porous media. In this paper, a conceptual mobile¯immobile¯zone (MIZ) model is pr...

  14. Ensemble Kalman Filter (EnKF) Used to Estimate the Multiphase Model Parameters for DNAPL Infiltration Experiments in Heterogeneous Porous Media

    NASA Astrophysics Data System (ADS)

    Shi, X.; Zheng, F.; Xu, H.; Sun, Y.; Wu, J.

    2014-12-01

    A series of 2-D sandbox experiments were conducted to investigate the infiltration behavior of dense non-aqueous phase liquids (DNAPL) in saturated heterogeneous porous media. The modified light transmission (LT) method based on Bob et al. (2008) was used to quantify the DNAPL saturation during the infiltration process. A multiphase numerical simulator T2VOC was then used to simulate the experiments. With the EnKF method, static parameters such as permeability, porosity, residual NAPL saturation, and van Genutchen parameters (such as αnw and n), and dynamic variables like DNAPL saturation were continuously updated to match with the realtime observation data from LT method for history matching purposes. It is shown that the EnKF sometimes fails badly in the analysis (or updating) of saturations due to the nonlinearity between model variables and observable variables. Common sequential data assimilation algorithms based on the Kalman filter were also compared and discussed about the multiphase flow problem in porous media. Acknowledgements This research was financially supported by the National Nature Science Foundation of China grants No. 41030746 and 41172206. Reference [1] Bob, M.M., Brooks, M.C., Mravik, S.C., Wood, A.L., 2008. A modified light transmission visualization method for DNAPL saturation measurements in 2-D models. Adv. Water Resour., 31, 727-742.

  15. DEMONSTRATION OF IN SITU DEHALOGENATION OF DNAPL THROUGH INJECTION OF EMULSIFIED ZERO-VALIENT IRON AT LAUNCH COMPLEX 34 IN CAPE CANAVERAL AIR FORCE STATION, FLORIDA

    EPA Science Inventory

    The purpose of this project was to evaluate the technical and cost performance of emulsified zero-valent iron (EZVI) technology when applied to DNAPL contaminants in the saturated zone. This demonstration was conducted at Launch Complex 34, Cape Canaveral Air Force Station, FL, w...

  16. Demonstration of Resistive Heating Treatment of DNAPL Source Zone at Launch Complex 34 in Cape Canaveral Air Force Station, Florida, Final Innovative Technology Evaluation Report

    EPA Science Inventory

    The Interagency DNAPL Consortium (IDC) was formally established in 1999 by the U.S. Department of Energy, U.S. Environmental Protection Agency, the U.S. Department of Defense, and the National Aeronautics and Space Administration. The IDC performed five remediation techniques: ...

  17. THE VELOCITY OF DNAPL FINGERING IN WATER-SATURATED POROUS MEDIA LABORATORY EXPERIMENTS AND A MOBILE-IMMOBILE-ZONE MODEL. (R826157)

    EPA Science Inventory

    Dense nonaqueous phase liquids (DNAPLs) are immiscible with water and can give rise to highly fingered fluid distributions when infiltrating through water-saturated porous media. In this paper, a conceptual mobile¯immobile¯zone (MIZ) model is pr...

  18. Study of penetration behavior of PCB-DNAPL in a sand layer by a column experiment.

    PubMed

    Okuda, Nobuyasu; Shimizu, Takaaki; Muratani, Masaru; Terada, Akihiko; Hosomi, Masaaki

    2014-11-01

    To better understand the infiltration performances of high concentration PCB oils (KC-300 and KC-1000 polychlorinated biphenyl (PCB) mixtures), representative dense non-aqueous phase liquid (DNAPL), under both saturated and unsaturated conditions, we conducted experiments on a sand column filled with Toyoura Standard Sand. When PCB oil with the volume comparable to the total porosity in the column was supplied, the residual PCB concentrations under PCB-water conditions were 4.9×10(4)mgkg(-1) in KC-300 and 3.9×10(4)mgkg(-1) in KC-1000. Under PCB-air conditions, residual PCB concentrations were 6.0×10(4)mgkg(-1) and 2.4×10(5)mgkg(-1) in the upper and lower parts for KC-300 and 3.6×10(4)mgkg(-1) and 1.5×10(5)mgkg(-1) in those for KC-1000, respectively, while the rest of the PCBs were infiltrated. On the other hand, when a small amount of PCB oil with the volume far smaller than the total porosity in the column was supplied, the original PCBs were not transported via water permeation. However, lower-chlorinated PCB congeners-e.g., di- or tri-chlorinated biphenyls-preferentially dissolved and were infiltrated from the bottom of the column. These propensities on PCB oil infiltration can be explained in conjunction with the degree of PCB saturation in the sand column. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Behavior of DNAPL mixture of organometallic and chlorinated solvent in the presence of surfactants and alcohols as density modifying agents.

    PubMed

    Talawat, Jaruwan; Sabatini, David A; Tongcumpou, Chantra

    2013-01-01

    This work evaluates the behavior of surfactant and alcohols in combination with a mixture of tributyltinchloride (TBT) and tetrachloroethylene (PCE) with the goal of modifying the mixed oil from being a dense non-aqueous phase liquid (DNAPL) to a light non-aqueous phase liquid (LNAPL). Phase behavior of the mixed oil was studied under various combinations of surfactant, alcohol, and salinity. Phase density conversion was examined using pseudo-ternary phase diagrams constructed between the mixed oil, surfactant solution (4 wt%), and two types of alcohols (n-butyl alcohol (BuOH) and tert-butyl alcohol (TBA)). Aqueous phase solubilization and oil phase density modification were studied at varying alcohol to surfactant (A/S) ratios. The results showed that the optimum surfactant system was sodium dihexylsulfosuccinate (SDHS) and hexadecyl diphenyloxidedisulfonate (C16DPDS) (3.6 wt% and 0.4 wt%, respectively) with salt (NaCl) of 3 wt%. From pseudo-ternary phase diagrams, BuOH was found to produce a larger LNAPL region than TBA. From solubilization studies, the surfactant system plus either TBA or BuOH caused PCE preferential solubilization and this preference was more pronounced at higher total surfactant concentration in the system with TBA addition. In terms of density modification, BuOH produced lower oil density than TBA at high A/S ratio. This phase behavior knowledge can be used to optimize site remediation of organometallic DNAPLs.

  20. In-situ biochemical remediation of chlorinated organic compounds present as DNAPL using vitamin B12 and reduced titanium

    SciTech Connect

    Lesage, S.; Sorel, D.; Cherry, J.A.

    1995-12-31

    The feasibility of using a biochemical treatment for the cleanup of DNAPL solvents in the saturated zone was tested using an in-situ large vertical column. Laboratory column studies have shown that a mixture of vitamin B12 and titanium citrate pumped through a column containing 100 {mu}L of tetrachloroethene can completely dissolve and degrade the residual to ethene in a few days. A vertical test column, 80 cm in diameter was installed within a sheet-pile cell isolating a portion of aquifer at CFB Borden. An equimolar mixture of tetrachloroethene and 1,1,1-trichloroethane was injected below the water table to form a residual DNAPL. The injection withdrawal system was operated in an upward flow mode over a 2 m height. In order for the reaction to be proceed, the in-situ pH must be greater than 7 and the Eh lower than -480 mV. The redox of the aquifer and the formation of reaction products was monitored on site, through 8 side pods equipped with stainless steel tubing terminated with 40 {mu}m porous cups, installed at different heights in the test column. The volatile products at the withdrawal well were monitored on-line by dynamic headspace analysis/gas chromatography.

  1. Numerical Modeling Analysis of Hydrodynamic and Microbial Controls on DNAPL Pool Dissolution and Detoxification: Dehalorespirers in Co-culture

    SciTech Connect

    Wesseldyke, Eric S.; Becker, Jennifer G.; Seagren, Eric A.; Mayer, Alex S.; Zhang, Changyong

    2015-04-01

    Dissolution of dense non-aqueous phase liquid (DNAPL) contaminants like tetrachloroethene (PCE) can be “bioenhanced” via biodegradation, which increases the concentration gradient at the DNAPL–water interface. Model simulations were used to evaluate the impact of ecological interactions between different dehalorespiring strains and hydrodynamics on the bioenhancement effect and the extent of PCE dechlorination. Simulations were performed using a two-dimensional coupled flow-transport model, with a DNAPL pool source and two microbial species, Dehalococcoides mccartyi 195 and Desulfuromonas michiganensis, which compete for electron acceptors (e.g., PCE), but not for their electron donors. Under biostimulation, low vx conditions, D. michiganensis alone significantly enhanced dissolution by rapidly utilizing aqueous-phase PCE. In co-culture under these conditions, D. mccartyi 195 increased this bioenhancement modestly and greatly increased the extent of PCE transformation. Although D. michiganensis was the dominant population under low velocity conditions, D. mccartyi 195 dominated under high velocity conditions due to bioclogging effects.

  2. Liquid-liquid mass transfer of partitioning electron donors in chlorinated solvent source zones.

    PubMed

    Cápiro, Natalie L; Granbery, Emmie K; Lebrón, Carmen A; Major, David W; McMaster, Michaye L; Pound, Michael J; Löffler, Frank E; Pennell, Kurt D

    2011-02-15

    A combination of batch and column experiments evaluated the mass transfer of two candidate partitioning electron donors (PEDs), n-hexanol (nHex) and n-butyl acetate (nBA), for enhanced bioremediation of trichloroethene (TCE)-dense nonaqueous phase liquid (DNAPL). Completely mixed batch reactor experiments yielded equilibrium TCE-DNAPL and water partition coefficients (KNW) for nHex and nBA of 21.7 ± 0.27 and 330.43 ± 6.7, respectively, over a range of initial PED concentrations up to the aqueous solubility limit of ca. 5000 mg/L. First-order liquid-liquid mass transfer rates determined in batch reactors with nBA or nHex concentrations near the aqueous solubility were 0.22 min(-1) and 0.11 min(-1), respectively. Liquid-liquid mass transfer under dynamic flow conditions was assessed in one-dimensional (1-D) abiotic columns packed with Federal Fine Ottawa sand containing a uniform distribution of residual TCE-DNAPL. Following pulse injection of PED solutions at pore-water velocities (vp) ranging from 1.2 to 6.0 m/day, effluent concentration measurements demonstrated that both nHex and nBA partitioned strongly into residual TCE-DNAPL with maximum effluent levels not exceeding 35% and 7%, respectively, of the applied concentrations of 4000 to 5000 mg/L. PEDs persisted at effluent concentrations above 5 mg/L for up to 16 and 80 pore volumes for nHex and nBA, respectively. Mathematical simulations yielded KNW values ranging from 44.7 to 48.2 and 247 to 291 and liquid-liquid mass transfer rates of 0.01 to 0.03 min(-1) and 0.001 to 0.006 min(-1) for nHex and nBA, respectively. The observed TCE-DNAPL and water mass transfer behavior suggests that a single PED injection can persist in a treated source zone for prolonged time periods, thereby reducing the need for, or frequency of, repeated electron donor injections to support bacteria that derive reducing equivalents for TCE reductive dechlorination from PED fermentation.

  3. The application of phospholipid removal columns and ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry for quantification of multi-class antibiotics in aquaculture samples.

    PubMed

    Reinholds, Ingars; Pugajeva, Iveta; Perkons, Ingus; Bartkevics, Vadims

    2016-09-05

    In this study a robust and sensitive method based on a proposed sample purification procedure, using zirconia-coated Phree™ columns and analysis by ultra-high performance liquid chromatography with triple quadrupole tandem mass spectrometry are presented for the assessment of multi-class antibiotics in farmed fish species. The sample preparation procedure benefited from combined precipitation of proteins and selective removal of phospholipids by Phree™ columns, resulting in a high sensitivity of the method (LOQ 0.3-9mgkg(-1)). The in-house validation results (precision, repeatability, decision limit CCα, detection capability CCβ, etc.) indicate that the elaborated method is fully suitable for the analysis of the main classes of antibiotics in accordance with the European Union (EU) Commission Decision 2002/657/EC. The method was applied to the analysis of antibiotics in trout and sturgeon samples obtained from the local inland aquacultures in Latvia. The results revealed the presence of two antibiotics (enrofloxacin and trimethoprim) in 12 out of the 20 analysed fish samples at concentrations (0.33-12.2μgkg(-1)) below the MRLs, thus causing no acute risks to consumers. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. In-Situ Anaerobic Biosurfactant Production Process For Remediation Of DNAPL Contamination In Subsurface Aquifers

    NASA Astrophysics Data System (ADS)

    Albino, J. D.; Nambi, I. M.

    2009-12-01

    microbial cultures. The microorganisms responsible for biosurfactant production was isolated and identified as Pseudomonas Sp (designated as Pseudomonas Sp ANBIOSURF-1, Gene bank no: FJ930079), Pseudomonas stutzeri (MTCC 10033), Pseudomonas Sp (MTCC 10032) from groundwater, soil and municipal sewage sludge enrichments respectively. This study confirms that biosurfactants can be produced under anaerobic conditions and also in sufficient quantities. The cultures were also able to cometabolically degrade PCE to Ethylene. The isolated microorganisms can be used for remediation of DNAPL contaminated sites by in-situ biosurfactant production.

  5. Restricted access supramolecular solvents for removal of matrix-induced ionization effects in mass spectrometry: Application to the determination of Fusarium toxins in cereals.

    PubMed

    García-Fonseca, Sergio; Rubio, Soledad

    2016-02-01

    Ion suppression/enhancement caused by matrix effects continues being a major concern in liquid chromatography-mass spectrometry (LC-MS). This research explores the ability of a supramolecular solvent (SUPRAS) made up of inverted hexagonal aggregates of oleic acid to behave as a liquid with restricted access properties (SUPRAS-RAM). Fusarium toxins in cereals were extracted with the oleic acid-based SUPRAS-RAM prior to their quantification by LC-electrospray ionization (ESI)-ion trap-MS (LC-ESI-IT-MS) in order to investigate the capability of this solvent to remove or reduce ionization suppression and/or enhancement in the analysis of complex samples by MS. The method involved the vortex-shaking of 300 mg of cereal with 600 μL of the SUPRAS-RAM for 15 min, centrifugation for separation of the supernatant and quantitation by LC-ESI-IT-MS. Macromolecules such as proteins and carbohydrates were excluded from extraction by chemical and physical mechanisms. Extraction of analytes and sample clean-up were thus carried out in a single step. No evaporation of the extracts was needed. Method detection limits for the legislated Fusarium toxins [i.e. deoxynivalenol (DON), zearalenone (ZEA) and fumonisins B1 (FB1) and B2 (FB2)] were 15 μg kg(-1) for DON and ZEA and 8 μg kg(-1) for fumonisins. These values were far below the maximum levels set by the European Commission for these toxins in foodstuffs. The method was successfully applied to the determination of these toxins in wheat and maize harvested in the South of Spain. No contamination of Fusarium toxins was found in samples at detectable levels. Recoveries in spiked samples were in the range 87-105%, with relative standard deviations between 1 and 7%. The use of the oleic acid-based SUPRAS-RAM effectively removed matrix interferences and allowed reliable quantitation of Fusarium toxins in cereals using solvent-based calibration.

  6. Adenoid removal

    MedlinePlus

    ... taken out at the same time as the tonsils ( tonsillectomy ). Adenoid removal is also called adenoidectomy. The procedure is most often done in children. ... can be removed again if necessary. Alternative Names Adenoidectomy; Removal of ... Instructions Tonsil and adenoid removal - discharge Tonsil removal - what to ...

  7. Determining estrogenic steroids in Taipei waters and removal in drinking water treatment using high-flow solid-phase extraction and liquid chromatography/tandem mass spectrometry.

    PubMed

    Chen, Chia-Yang; Wen, Tzu-Yao; Wang, Gen-Shuh; Cheng, Hui-Wen; Lin, Ying-Hsuan; Lien, Guang-Wen

    2007-06-01

    River water and wastewater treatment plant (WWTP) effluents from metropolitan Taipei, Taiwan were tested for the presence of the pollutants estrone (E1), estriol (E3), 17beta-estradiol (E2), and 17alpha-ethinylestradiol (EE2) using a new methodology that involves high-flow solid-phase extraction and liquid chromatography/tandem mass spectrometry. The method was also used to investigate the removal of the analytes by conventional drinking water treatment processes. Without adjusting the pH, we extracted 1-L samples with PolarPlus C18 Speedisks under a flow rate exceeding 100 mL/min, in which six samples could be done simultaneously using an extraction station. The adsorbent was washed with 40% methanol/60% water and then eluted by 50% methanol/50% dichloromethane. The eluate was concentrated until almost dry and was reconstituted by 20 microL of methanol. Quantitation was done by LC-MS/MS-negative electrospray ionization in the selected reaction monitoring mode with isotope-dilution techniques. The mobile phase was 10 mM N-methylmorpholine aqueous solution/acetonitrile with gradient elution. Mean recoveries of spiked Milli-Q water were 65-79% and precisions were within 2-20% of the tested concentrations (5.0-200 ng/L). The method was validated with spiked upstream river water; precisions were most within 10% of the tested concentrations (10-100 ng/L) with most RSDs<10%. LODs of the environmental matrixes were 0.78-7.65 ng/L. A pre-filtration step before solid-phase extraction may significantly influence the measurement of E1 and EE2 concentrations; disk overloading by water matrix may also impact analyte recoveries along with ion suppression. In the Taipei water study, the four steroid estrogens were detected in river samples (ca. 15 ng/L for E2 and EE2 and 35-45 ng/L for E1 and E3). Average levels of 19-26 ng/L for E1, E2, and EE2 were detected in most wastewater effluents, while only a single effluent sample contained E3. The higher level in the river was likely

  8. Liquid chromatography mass spectrometry determination of perfluoroalkyl acids in environmental solid extracts after phospholipid removal and on-line turbulent flow chromatography purification.

    PubMed

    Mazzoni, M; Polesello, S; Rusconi, M; Valsecchi, S

    2016-07-01

    An on-line TFC (Turbulent Flow Chromatography) clean up procedures coupled with UHPLC-MS/MS (Ultra High Performance Liquid Chromatography Mass Spectrometry) multi-residue method was developed for the simultaneous determination of 8 perfluroalkyl carboxylic acids (PFCA, from 5 to 12 carbon atoms) and 3 perfluoroalkyl sulfonic acids (PFSA, from 4 to 8 carbon atoms) in environmental solid matrices. Fast sample preparation procedure was based on a sonication-assisted extraction with acetonitrile. Phospholipids in biological samples were fully removed by an off-line SPE purification before injection, using HybridSPE(®) Phospholipid Ultra cartridges. The development of the on-line TFC clean-up procedure regarded the choice of the stationary phase, the optimization of the mobile phase composition, flow rate and injected volume. The validation of the optimized method included the evaluation of matrix effects, accuracy and reproducibility. Signal suppression in the analysis of fortified extracts ranged from 1 to 60%, and this problem was overcome by using isotopic dilution. Since no certified reference materials were available for PFAS in these matrices, accuracy was evaluated by recoveries on spiked clam samples which were 98-133% for PFCAs and 40-60% for PFSAs. MLDs and MLQs ranged from 0.03 to 0.3ngg(-1) wet weight and from 0.1 to 0.9ngg(-1) wet weight respectively. Repeatability (intra-day precision) and reproducibility (inter-day precision) showed RSD from 3 to 13% and from 4 to 27% respectively. Validated on-line TFC/UHPLC-MS/MS method has been applied for the determination of perfluoroalkyl acids in different solid matrices (sediment, fish, bivalves and bird yolk). Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Application of a NAPL partitioning interwell tracer test (PITT) to support DNAPL remediation at the Sandia National Laboratories/New Mexico chemical waste landfill

    SciTech Connect

    Studer, J.E.; Mariner, P.; Jin, M.

    1996-05-01

    Chlorinated solvents as dense non-aqueous phase liquid (DNAPL) are present at a large number of hazardous waste sites across the U.S. and world. DNAPL is difficult to detect in the subsurface, much less characterize to any degree of accuracy. Without proper site characterization, remedial decisions are often difficult to make and technically effective, cost-efficient remediations are even more difficult to obtain. A new non-aqueous phase liquid (NAPL) characterization technology that is superior to conventional technologies has been developed and applied at full-scale. This technology, referred to as the Partitioning Interwell Tracer Test (PITT), has been adopted from oil-field practices and tailored to environmental application in the vadose and saturated zones. A PITT has been applied for the first time at full-scale to characterize DNAPL in the vadose zone. The PITT was applied in December 1995 beneath two side-by-side organic disposal pits at Sandia National Laboratories/New Mexico (SNL/NM) RCRA Interim Status Chemical Waste Landfill (CWL), located in Albuquerque, New Mexico. DNAPL, consisting of a mixture of chlorinated solvents, aromatic hydrocarbons, and PCE oils, is known to exist in at least one of the two buried pits. The vadose zone PITT was conducted by injecting a slug of non-partitioning and NAPL-partitioning tracers into and through a zone of interest under a controlled forced gradient. The forced gradient was created by a balanced extraction of soil gas at a location 55 feet from the injector. The extracted gas stream was sampled over time to define tracer break-through curves. Soil gas sampling ports from multilevel monitoring installations were sampled to define break-through curves at specific locations and depths. Analytical instrumentation such as gas chromatographs and a photoacoustical analyzers operated autonomously, were used for tracer detection.

  10. Comparison of two-dimensional and three-dimensional simulations of dense nonaqueous phase liquids (DNAPLs): Migration and entrapment in a nonuniform permeability field

    NASA Astrophysics Data System (ADS)

    Christ, John A.; Lemke, Lawrence D.; Abriola, Linda M.

    2005-01-01

    The influence of reduced dimensionality (two-dimensional (2-D) versus 3-D) on predictions of dense nonaqueous phase liquid (DNAPL) infiltration and entrapment in statistically homogeneous, nonuniform permeability fields was investigated using the University of Texas Chemical Compositional Simulator (UTCHEM), a 3-D numerical multiphase simulator. Hysteretic capillary pressure-saturation and relative permeability relationships implemented in UTCHEM were benchmarked against those of another lab-tested simulator, the Michigan-Vertical and Lateral Organic Redistribution (M-VALOR). Simulation of a tetrachloroethene spill in 16 field-scale aquifer realizations generated DNAPL saturation distributions with approximately equivalent distribution metrics in two and three dimensions, with 2-D simulations generally resulting in slightly higher maximum saturations and increased vertical spreading. Variability in 2-D and 3-D distribution metrics across the set of realizations was shown to be correlated at a significance level of 95-99%. Neither spill volume nor release rate appeared to affect these conclusions. Variability in the permeability field did affect spreading metrics by increasing the horizontal spreading in 3-D more than in 2-D in more heterogeneous media simulations. The assumption of isotropic horizontal spatial statistics resulted, on average, in symmetric 3-D saturation distribution metrics in the horizontal directions. The practical implication of this study is that for statistically homogeneous, nonuniform aquifers, 2-D simulations of saturation distributions are good approximations to those obtained in 3-D. However, additional work will be needed to explore the influence of dimensionality on simulated DNAPL dissolution.

  11. In situ, field-scale evaluation of surfactant-enhanced DNAPL recovery using a single-well, ``push-pull'' test

    SciTech Connect

    Istok, J.D.; Field, J.A.

    1999-10-01

    The overall goal of this project was to further develop the single-well, ``push-pull'' test method as a feasibility assessment and site-characterization tool for studying the fundamental fate and transport behavior of injected surfactants and their ability to solubilize and mobilize dense nonaqueous phase liquids (DNAPLs) in the subsurface. The specific objectives were to develop a modified push-pull test for use in identifying and quantifying the effects of sorption, precipitation, and biodegradation on the fate and transport of injected surfactants, use the developed test method to quantify the effects of these processes on the ability of injected surfactants to solubilize and mobilize residual phase trichloroethane (TCE), and demonstrate the utility of the developed test method for performing site characterization and feasibility studies for surfactant-enhanced DNAPL recovery systems in the field. The results from the intermediate-scale laboratory experiments conducted for this project indicate that the single-well, push-pull test method can provide quantitative information on the effectiveness of injected surfactants in enhancing DNAPL solubilization in natural aquifer sediments. Specifically, the results of this research demonstrate the ability of the single-well, push-pull test to characterize the behavior of multi-component surfactants in the presence of natural aquifer sediment under laboratory and in-situ field conditions.

  12. The Migration and Entrapment of DNAPLs in Physically and Chemically Heterogeneous Porous Media - Final Report - 09/15/1996 - 09/15/2000

    SciTech Connect

    Abriola, L. M.; Demond, A. H.

    2000-09-15

    Hazardous dense nonaqueous phase liquids (DNAPLs), such as chlorinated solvents, are slightly water soluble and pose a serious threat to soil and groundwater supplies in many portions of the United States. The migration and entrapment of DNAPLs in the subsurface environment is typically believed to be controlled by physical heterogeneities; i.e, layers and lenses of contrasting soil texture. The rationale for this assumption is that capillarity, as determined by the soil texture, is the dominant transport mechanism. Capillarity also depends on interfacial tension and medium wettability. Interfacial tension and medium wettability may be spatially and temporally dependent due to variations in aqueous phase chemistry, contaminant aging, and/or variations in mineralogy and organic matter distributions. Such chemical heterogeneities have largely been ignored to date, even though they are known to have dramatic effects on the hydraulic property relations. Numerical multiphase flow and transport models typically assume that solids are water-wet and that interfacial tension is constant. The primary objective of this research is to investigate the influence of coupled physical and chemical heterogeneities on the migration and entrapment of DNAPLs. This objective will be accomplished through a combination of laboratory and numerical experiments. Laboratory experiments will be conducted to examine: (i) aqueous phase chemistry effects on medium wettability and interfacial tension; and (ii) relative permeability-saturation-capillary pressure relations for chemically heterogeneous systems. An important objective of this research is to modify a two-dimensional multiphase flow and transport model to account for chemically and physically heterogeneous systems. This numerical simulator will be used in conjunction with independently measured parameters to simulate two-dimensional DNAPL infiltration experiments. Comparisons of simulated and laboratory data will provide a means to

  13. CONCURRENT INJECTION OF COSOLVENT AND AIR FOR ENHANCED PCE REMOVAL

    EPA Science Inventory

    The goal of this study was to use preferential flow of air to improve the dynamics of cosolvent displacement in order to enhance DNAPL displacement and dissolution. The concurrent injection of cosolvent and air was evaluated in a glass micromodel for a DNAPL remediation technolog...

  14. CONCURRENT INJECTION OF COSOLVENT AND AIR FOR ENHANCED PCE REMOVAL

    EPA Science Inventory

    The goal of this study was to use preferential flow of air to improve the dynamics of cosolvent displacement in order to enhance DNAPL displacement and dissolution. The concurrent injection of cosolvent and air was evaluated in a glass micromodel for a DNAPL remediation technolog...

  15. Determining effective interfacial tension and predicting finger spacing for DNAPL penetration into water-saturated porous media.

    PubMed

    Smith, J E; Zhang, Z F

    2001-03-01

    The difficulty in determining the effective interfacial tension limits the prediction of the wavelength of fingering of immiscible fluids in porous media. A method to estimate the effective interfacial tension using fractal concepts was presented by Chang et al. [Water Resour. Res. 30 (1994) 125]. We modified the method in that the macroscopic interface length was used instead of the system width. Methods to determine the macroscopic and the microscopic interface length are given. Lab experiments of dense nonaqueous phase liquid (DNAPL) penetrating into water-saturated glass beads were carried out in a two-dimensional (2-D) transparent chamber. The displacement processes were recorded using a 35-mm camera or a video camera, which was directly connected to and controlled by a computer. Unlike the method of Chang et al. (1994), the modified method used here gives a constant value of the effective interfacial tension over time. The predicted wavelengths of fingering are relatively close to those observed except for the fine beads.

  16. Improved time-lapse electrical resistivity tomography monitoring of dense non-aqueous phase liquids with surface-to-horizontal borehole arrays

    NASA Astrophysics Data System (ADS)

    Power, Christopher; Gerhard, Jason I.; Tsourlos, Panagiotis; Soupios, Pantelis; Simyrdanis, Kleanthis; Karaoulis, Marios

    2015-01-01

    Electrical resistivity tomography (ERT) has long-standing potential to improve characterization of sites contaminated with dense non-aqueous phase liquids (DNAPLs). However, ERT is rarely used at DNAPL sites due to the complexity of the DNAPL target coupled with the inherent limitations of traditional (surface and cross-hole) ERT configurations. Horizontal boreholes are being increasingly used in remedial strategies at contaminated field sites. This paper presents a novel surface-to-horizontal borehole (S2HB) ERT configuration for DNAPL site investigations. This array configuration is combined with four-dimensional (4D) inversion methods (applied on two-dimensional (2D) time-lapse monitoring datasets) to explore the potential benefit of S2HB ERT for mapping the spatial and temporal evolution of DNAPL mass during remediation. A field scale DNAPL remediation scenario was first simulated by a coupled DNAPL-ERT model. This demonstrated that S2HB ERT may provide significant improvements over surface ERT, particularly for delineating DNAPL mass removal at depth. A laboratory experiment was then performed to validate the S2HB ERT approach in a physical system. The experiment confirmed that 4D S2HB ERT provides improved time-lapse monitoring of NAPL changes. Confidence in the ERT responses obtained from the experiment was increased by direct comparison to the actual distribution of NAPL mapped by excavation. Independent simulation of the experiment with the DNAPL-ERT model demonstrated that the model is reliable for simulating real systems. This initial study demonstrates significantly improved resistivity imaging with surface-to-horizontal borehole ERT and its potential as a non-destructive site characterization tool for mapping DNAPL mass changes during remediation.

  17. Environmental behavior of explosives in groundwater from the Milan Army Ammunition Plant in aquatic and wetland plant treatments. Removal, mass balances and fate in groundwater of TNT and RDX.

    PubMed

    Best, E P; Sprecher, S L; Larson, S L; Fredrickson, H L; Bader, D F

    1999-06-01

    Phytoremediation of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in groundwater using constructed wetlands is a potentially economical remediation alternative. To evaluate Explosives removal and fate was evaluated using hydroponic batch incubations of plant and substrate treatments with explosives-contaminated groundwater amended with [U-14C]-TNT or [U-14C]-RDX. Plants and substrates were collected from a small-scale wetland constructed for explosives removal, and groundwater originated from a local aquifer at the Milan Army Ammunition Plant. The study surveyed three aquatic, four wetland plant species and two substrates in independent incubations of 7 days with TNT and 13 days with RDX. Parent compounds and transformation products were followed using 14C and chemical (HPLC) analyses. Mass balance of water, plants, substrates and air was determined. It was demonstrated that TNT disappeared completely from groundwater incubated with plants, although growth of most plants except parrot-feather was low in groundwater amended to contain 1.6 to 3.4 mg TNT L-1. Highest specific removal rates were found in submersed plants in water star-grass and in all emergent plants except wool-grass. TNT declined less with substrates, and least in controls without plants. Radiolabel was present in all plants after incubation. Mineralization to 14CO2 was very low, and evolution into 14C-volatile organics negligible. RDX disappeared less rapidly than TNT from groundwater. Growth of submersed plants was normal, but that of emergent plants reduced in groundwater amended to contain 1.5 mg RDX L-1. Highest specific RDX removal rates were found in submersed plants in elodea, and in emergent plants in reed canary grass. RDX failed to disappear with substrates. Mineralization to 14CO2 was low, but relatively higher than in the TNT experiment. Evolution into 14C-volatile organics was negligible. Important considerations for using certain aquatic and wetland

  18. Monitoring Genetic & Metabolic Potential for In Situ Bioremediation: Mass Spectrometry

    SciTech Connect

    Buchanan, Michelle V.; Hurst, Gregory B.; Lidstrom, Mary E.; Auman, Anne; Britt, Phillip F.; Costello, Andria; Doktycz, Mitchel; Kim, Yongseong

    1999-06-01

    A number of DOE sites are contaminated with dense non-aqueous phase liquids (DNAPLs) such as carbon tetrachloride and trichloroethylene. At many of these sites, microbial bioremediation is an attractive strategy for cleanup, since it has the potential to degrade DNAPLs in situ. A rapid screening method to determine the broad range potential of a site's microbial population for contaminant degradation would greatly facilitate assessment for in situ bioremediation, as well as for monitoring ongoing bioremediation treatment. Current laboratory based treatability methods are cumbersome and expensive. In this project, we are developing methods based on matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for rapid and accurate detection of polymerase chain reaction (PCR) products from microbial genes involved in biodegradation of pollutants. PCR primers are being developed to amplify DNA sequences that are amenable to MALDI-MS detection. This work will lay the foundation for development of a field-portable MS-based technique for rapid on site assessment and monitoring of bioremediation processes.

  19. Tick Removal

    MedlinePlus

    ... diseases Tickborne diseases abroad Borrelia miyamotoi Borrelia mayonii Mobile Application Tick Removal Recommend on Facebook Tweet Share Compartir If you find a tick attached to your skin, there's no need to panic. There are several tick removal devices on the market, but a plain set of ...

  20. Improved Monitoring Methods for Performance Assessment During Remediation of DNAPL Source Zones

    DTIC Science & Technology

    2010-04-01

    anionic surfactant has the potential to interact with porous media. Lee et al. (2002) found that an increase in clay content will increase DowFax...adsorption to clay , thereby removing the surfactant from the aqueous phase such that contaminant solubility is reduced. Cho et al. (2004) observed the...Media type Sand Loamy sand w/ high NOM Sand Loamy sand w/ low NOM Clay Media source Commercial Sand 2 NTC site 3 Media #4 10 - 15 ft. bgs NTC

  1. The influence of cosolvent and heat on the solubility and reactivity of organophosphorous pesticide DNAPL alkaline hydrolysis.

    PubMed

    Muff, Jens; MacKinnon, Leah; Durant, Neal D; Bennedsen, Lars Frausing; Rügge, Kirsten; Bondgaard, Morten; Pennell, Kurt

    2016-11-01

    The presented research concerned the compatibility of cosolvents with in situ alkaline hydrolysis (ISAH) for treatment of organophosphorous (OPP) pesticide contaminated sites. In addition, the influence of moderate temperature heat increments was studied as a possible enhancement method. A complex dense non-aqueous phase liquid (DNAPL) of primarily parathion (~50 %) and methyl parathion (~15 %) obtained from the Danish Groyne 42 site was used as a contaminant source, and ethanol and propan-2-ol (0, 25, and 50 v/v%) was used as cosolvents in tap water and 0.34 M NaOH. Both cosolvents showed OPP solubility enhancement at 50 v/v% cosolvent content, with slightly higher OPP concentrations reached with propan-2-ol. Data on hydrolysis products did not show a clear trend with respect to alkaline hydrolysis reactivity in the presence of cosolvents. Results indicated that the hydrolysis rate of methyl-parathion (MP3) decreased with addition of cosolvent, whereas the hydrolysis rate of ethyl-parathion (EP3) remained constant, and overall indications were that the hydrolysis reactions were limited by the rate of hydrolysis rather than NAPL dissolution. In addition to cosolvents, the influence of low-temperature heating on ISAH was studied. Increasing reaction temperature from 10 to 30 °C provided an average rate of hydrolysis enhancement by a factor of 1.4-4.8 dependent on the base of calculation. When combining 50 v/v% cosolvent addition and heating to 30 °C, EP3 solubility was significantly enhanced and results for O,O-diethyl-thiophosphoric acid (EP2 acid) showed a significant enhancement of hydrolysis as well. However, this could not be supported by para-nitrophenol (PNP) data indicating the instability of this product in the presence of cosolvent.

  2. Characterisation of a DNAPL source zone in a porous aquifer using the Partitioning Interwell Tracer Test and an inverse modelling approach.

    PubMed

    Dridi, Lotfi; Pollet, Ingrid; Razakarisoa, Olivier; Schäfer, Gerhard

    2009-06-26

    In this paper, we discuss the results of a Partitioning Interwell Tracer Test (PITT) performed in a large scale experiment with a well-defined TCE spill, and present a novel combined analytical-numerical inverse modelling approach using measured concentration profiles within a TCE plume to predict the distribution of the DNAPL in a virtual vertical plane of the source. The proposed inverse modelling approach assumes local thermodynamic equilibrium of the distribution of TCE between the NAPL phase and the aqueous phase and no decay or sorption of the dissolved TCE concentrations downstream of the spill area. The analytical part of the inverse modelling approach contains two steps. As a first step, the location of the contaminant in a virtual vertical plane of a porous medium is fixed by using measured concentration profiles and considering the dissolution of the organic phase under equilibrium conditions. In the second step, the volume of contaminant entrapped in the source cells is estimated. A multiphase advective-dispersive transport model is used in the final step to adjust the volumes quantified in the second step. The predictions are highly dependent on the quantity and quality of the data in space and time. From the PITT-breakthrough curves measured at the pumping well, a mean TCE saturation in the sweep zone of 0.0004 was derived, which is very low compared to that determined at the local scale. In a second analysis, tracer breakthrough curves available at measuring points placed closely downstream and upstream of the presumed source zone, were used to explain why the globally obtained DNAPL saturation was very low compared to the "real", locally evaluated TCE saturations in the source zone. This was principally caused by the overall travel time compared to the short travel time of the tracers in the source zone. Another reason is that due to bypassing, only part of the volume of tracer injected had been in contact and had eventually interacted with the

  3. NON-INVASIVE DETERMINATION OF THE LOCATION AND DISTRBUTION OF FREE-PHASE DENSE NONAQUEOUS PHASE LIQUIDS (DNAPL) BY SEISMIC REFLECTION TECHNIQUES

    SciTech Connect

    Michael G. Waddell; William J. Domoracki; Jerome Eyer

    2003-01-01

    The Earth Sciences and Resources Institute, University of South Carolina is conducting a proof of concept study to determine the location and distribution of subsurface DNAPL carbon tetrachloride (CCl{sub 4}) contamination at the 216-Z-9 crib, 200 West area, DOE Hanford Site, Washington by use of two-dimensional high-resolution seismic reflection surveys and borehole geophysical data. The study makes use of recent advances in seismic reflection amplitude versus offset (AVO) technology to directly detect the presence of subsurface DNAPL. The techniques proposed are noninvasive means of site characterization and direct free-phase DNAPL detection. This final report covers the results of Tasks 1, 2, and 3. Task (1) contains site evaluation and seismic modeling studies. The site evaluation consists of identifying and collecting preexisting geological and geophysical information regarding subsurface structure and the presence and quantity of DNAPL. The seismic modeling studies were undertaken to determine the likelihood that an AVO response exists and its probable manifestation. Task (2) is the design and acquisition of 2-D seismic reflection data to image areas of probable high concentration of DNAPL. Task (3) is the processing and interpretation of the 2-D data. During the commission of these tasks four seismic reflection profiles were collected. Subsurface velocity information was obtained by vertical seismic profile surveys in three wells. The interpretation of these data is in two parts. Part one is the construction and interpretation of structural contour maps of the contact between the Hanford Fine unit and the underlying Plio/Pleistocene unit and of the contact between the Plio/Pleistocene unit and the underlying caliche layer. These two contacts were determined to be the most likely surfaces to contain the highest concentration CCl{sub 4}. Part two of the interpretation uses the results of the AVO modeling to locate any seismic amplitude anomalies that might be

  4. Spleen removal

    MedlinePlus

    ... and infections. It also helps filter the blood. Description The spleen is removed while you are under ... cuts in the belly. The surgeon inserts an instrument called a laparoscope through one of the cuts. ...

  5. Tattoo removal.

    PubMed

    Burris, Katy; Kim, Karen

    2007-01-01

    Tattoos have been a part of costume, expression, and identification in various cultures for centuries. Although tattoos have become more popular in western culture, many people regret their tattoos in later years. In this situation, it is important to be aware of the mechanisms of tattoo removal methods available, as well as their potential short- and long-term effects. Among the myriad of options available, laser tattoo removal is the current treatment of choice, given its safety and efficacy.

  6. DNAPL MAPPING AND WATER SATURATION MEASUREMENTS IN 2-D MODELS USING LIGHT TRANSMISSION VISUALIZATION (LTV) TECHNIQUE

    EPA Science Inventory

    • LTV can be used to characterize free phase PCE architecture in 2-D flow chambers without using a dye. • Results to date suggest that error in PCE detection using LTV can be less than 10% if the imaging system is optimized. • Mass balance calculations show a maximum error of 9...

  7. Tattoo removal.

    PubMed

    Adatto, Maurice A; Halachmi, Shlomit; Lapidoth, Moshe

    2011-01-01

    Over 50,000 new tattoos are placed each year in the United States. Studies estimate that 24% of American college students have tattoos and 10% of male American adults have a tattoo. The rising popularity of tattoos has spurred a corresponding increase in tattoo removal. Not all tattoos are placed intentionally or for aesthetic reasons though. Traumatic tattoos due to unintentional penetration of exogenous pigments can also occur, as well as the placement of medical tattoos to mark treatment boundaries, for example in radiation therapy. Protocols for tattoo removal have evolved over history. The first evidence of tattoo removal attempts was found in Egyptian mummies, dated to have lived 4,000 years BC. Ancient Greek writings describe tattoo removal with salt abrasion or with a paste containing cloves of white garlic mixed with Alexandrian cantharidin. With the advent of Q-switched lasers in the late 1960s, the outcomes of tattoo removal changed radically. In addition to their selective absorption by the pigment, the extremely short pulse duration of Q-switched lasers has made them the gold standard for tattoo removal. Copyright © 2011 S. Karger AG, Basel.

  8. Enhanced aqueous dissolution of a DNAPL source to characterize the source strength function

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Annable, Michael D.; Schaefer, Charles E.; Ault, Timothy D.; Cho, Jaehyun; Jawitz, James W.

    2014-11-01

    Simplified analytical solutions, developed as source strength functions (SSFs), are capable of describing the temporal dissolution of nonaqueous phase liquids in groundwater, which is useful for predicting source longevity and can serve as a guide for remedial activities. Here, SSF parameters were estimated by fitting enhanced aqueous dissolution data from a flow cell consisting of three injection and four extraction wells to analytical dissolution models (power law model (PLM) and equilibrium streamtube model (EST)) at a trichloroethene (TCE) contaminated site, Alameda Point, California. Both the PLM and the EST model were able to characterize the observed aqueous TCE dissolution during enhanced water flooding. Additional field activities conducted at the site included soil core collection, a recirculated partitioning tracer test, passive flux meter transects, and push-pull tracer tests. The additional site characterization data were used to independently estimate the observed SSF parameters using information such as the TCE mass, distribution and porous media heterogeneity. The exponential decay model (a subset of the PLM) accurately predicted the enhanced dissolution, likely because the site was significantly aged (most of the mass in the plume rather than in the source zone) or middle stage, and the mass in the source zone could be approximately estimated. The EST tracer-based model, when combined with data from the recirculated partitioning tracer test, soil cores, and the push-pull tracer test, was capable of accurately predicting the observed aqueous dissolution. The mass in the source zone and the fraction of contaminated flowpaths were the most important site characteristics, requiring the greatest accuracy to predict aqueous dissolution. Establishing steady state dissolution was essential to provide a more accurate estimate of the fraction contaminated and high resolution data from soil cores in the source zone were needed to estimate the mass present.

  9. Modeling the Impact of Cracking in Low Permeability Layers in a Groundwater Contamination Source Zone on Dissolved Contaminant Fate and Transport

    NASA Astrophysics Data System (ADS)

    Sievers, K. W.; Goltz, M. N.; Huang, J.; Demond, A. H.

    2011-12-01

    Dense Non-Aqueous Phase Liquids (DNAPLs), which are chemicals and chemical mixtures that are heavier than and only slightly soluble in water, are a significant source of groundwater contamination. Even with the removal or destruction of most DNAPL mass, small amounts of remaining DNAPL can dissolve into flowing groundwater and continue as a contamination source for decades. One category of DNAPLs is the chlorinated aliphatic hydrocarbons (CAHs). CAHs, such as trichloroethylene and carbon tetrachloride, are found to contaminate groundwater at numerous DoD and industrial sites. DNAPLs move through soils and groundwater leaving behind residual separate phase contamination as well as pools sitting atop low permeability layers. Recently developed models are based on the assumption that dissolved CAHs diffuse slowly from pooled DNAPL into the low permeability layers. Subsequently, when the DNAPL pools and residual DNAPL are depleted, perhaps as a result of a remediation effort, the dissolved CAHs in these low permeability layers still remain to serve as long-term sources of contamination, due to so-called "back diffusion." These recently developed models assume that transport in the low permeability zones is strictly diffusive; however field observations suggest that more DNAPL and/or dissolved CAH is stored in the low permeability zones than can be explained on the basis of diffusion alone. One explanation for these field observations is that there is enhanced transport of dissolved CAHs and/or DNAPL into the low permeability layers due to cracking. Cracks may allow for advective flow of water contaminated with dissolved CAHs into the layer as well as possible movement of pure phase DNAPL into the layer. In this study, a multiphase numerical flow and transport model is employed in a dual domain (high and low permeability layers) to investigate the impact of cracking on DNAPL and CAH movement. Using literature values, the crack geometry and spacing was varied to model

  10. Laboratory-Scale Column Testing Using IONSIV IE-911 for Removing Cesium from Acidic Tank Waste Simulant. 2: Determination of Cesium Exchange Capacity and Effective Mass Transfer Coefficient from a 500-cm3 Column Experiement

    SciTech Connect

    T.J. Tranter; R.D. Tillotson; T.A. Todd

    2005-04-01

    A semi-scale column test was performed using a commercial form of crystalline silicotitanate (CST) for removing radio-cesium from a surrogate acidic tank solution, which represents liquid waste stored at the Idaho National Engineering and Environmental Laboratory (INEEL). The engineered form of CST ion exchanger, known as IONSIVtmIE-911 (UOP, Mt. Laurel,NJ, USA), was tested in a 500-cm3 column to obtain a cesium breakthrough curve. The cesium exchange capacity of this column matched that obtained from previous testing with a 15-mc3 column. A numerical algorithm using implicit finite difference approximations was developed to solve the governing mass transport equations for the CST columns. An effective mass transfer coefficient was derived from solving these equations for previously reported 15 cm3 tests. The effective mass transfer coefficient was then used to predict the cesium breakthrough curve for the 500-cm3 column and compared to the experimental data reported in this paper. The calculated breakthrough curve showed excellent agreement with the data from the 500-cm3 column even though the interstitial velocity was a factor of two greater. Thus, this approach should provide a reasonable method for scale up to larger columns for treating actual tank waste.

  11. Mass spectrometric characterization of the Campylobacter jejuni adherence factor CadF reveals post-translational processing that removes immunogenicity while retaining fibronectin binding.

    PubMed

    Scott, Nichollas E; Marzook, N Bishara; Deutscher, Ania; Falconer, Linda; Crossett, Ben; Djordjevic, Steven P; Cordwell, Stuart J

    2010-01-01

    Campylobacter jejuni is a major gastrointestinal pathogen that colonizes host mucosa via interactions with extracellular matrix proteins, such as fibronectin (Fn). Fn-binding is mediated by a 37 kDa outer membrane protein termed Campylobacter adherence Factor (CadF). The outer membrane protein profile of a recent gastrointestinal C. jejuni clinical isolate (JHH1) was analysed using 2-DE and MS. Several spots were identified as products of the cadF gene. These included mass and pI variants of 34 and 30 kDa, as well as 24 kDa (CadF(24)) and 22 kDa (CadF(22)) mass variants. CadF variants were fully characterized by MALDI-TOF MS and MALDI-MS/MS. These data confirmed that CadF forms re-folding variants resulting in spots with lower mass and varying pI that are identical at the amino acid sequence level and are not modified post-translationally. CadF(22) and CadF(24), however, were characterized as N-terminal, membrane-associated polypeptides resulting from cleavage between serine(195) and leucine(196), and glycine(201) and phenylalanine(202), respectively. These variants were more abundant in the virulent (O) isolate of C. jejuni NCTC11168 when compared with the avirulent (genome sequenced) isolate. Hexahistidine fusion constructs of full-length CadF (34 kDa), CadF(24), and the deleted C-terminal OmpA domain (14 kDa; CadF(14)) were created in Escherichia coli. Recombinant CadF variants were probed against patient sera and revealed that only full-length CadF retained reactivity. Binding assays showed that CadF(24) retained Fn-binding capability, while CadF(14) did not bind Fn. These data suggest that the immunogenic epitope of CadF is cleaved to generate smaller Fn-binding polypeptides, which are not recognized by the host humoral response. CadF cleavage therefore may be associated with virulence in C. jejuni.

  12. Investigation on the removal of natural and synthetic estrogens using biofilms in continuous flow biofilm reactors and batch experiments analysed by gas chromatography/mass spectrometry.

    PubMed

    Pieper, Christina; Rotard, Wolfgang

    2011-01-01

    The degradation of the natural estrogen 17β-estradiol and the synthetic steroid hormone 17α-ethinylestradiol, two estrogens already detected in surface waters at low concentration levels, was investigated using continuous flow biofilm reactors and batch experiments. Biofilms in continuous flow experiments were created by natural organisms from river systems of the national park Unteres Odertal, Germany, whereas batch experiments were performed with isolated bacterial strains derived from biofilms. The analytical method, including solid phase extraction, silylation of analytes and measurement with GC/MS, was optimised for the target compounds 17β-estradiol, 17α-ethinylestradiol and the possible metabolites estrone and estriol. The performance characteristics of the analytical method, namely recovery, standard deviations, method detection limits (MDL) and method quantification limits (MQL), were evaluated for accurate interpretation of degradation experiments. Continuous flow biofilm reactors were operated with two different nutrient media under dosage of estradiol and ethinylestradiol. Both estrogens were rapidly degraded within several hours; the metabolite estrone (from estradiol as well as from ethinylestradiol) was detected in significant amounts and was further decomposed. In additional batch experiments using isolated bacterial strains from the natural biofilms to decompose estradiol and ethinylestradiol, different metabolisms of isolates were explored. Five of the 15 isolated bacterial strains tested degraded estradiol and ethinylestradiol with different degradation rates. The results suggest that biofilms from national park Unteres Odertal possess a high capability to aerobically decompose natural and also synthetic estrogens so that these microorganisms could provide enhanced removal of pollutants in municipal water treatment plants. Copyright © 2010 Elsevier Ltd. All rights reserved.

  13. Emulsified Zero-Valent Nano-Scale Iron Treatment of Chlorinated Solvent DNAPL Source Areas

    DTIC Science & Technology

    2010-04-01

    Integral Mass Flux Estimation and Reactive Transport Modelling in Heterogeneous Porous Media. Ph.D. Thesis . The University of Tübingen, Tübingen, Germany...1318. Schwarz, R. 2001. Grundwasser-Gefährdungs-abschätzung durch Emmissions- und Immissions-messungen an Deponien und Altlasten. Ph.D. Thesis ...34 ~· \\!L \\ •’ H )? (\\ " lit •• (<I •·’ ··’ (I I’ 11ə\\, ,, ,, ,, •• ,, ’>’·l •’ ,, •’ •• (I •’ Efl ~cts ot\\ Oroundwat~r Srunrles" by MJ Biu<:duna ct nl

  14. Field Testing of Bimetallic Nanoscale Particle Technology for In-Situ Groundwater Treatment of a Fractured Rock DNAPL Zone

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Walata, L.; Nash, R.; Gheorghiu, F.; Glazier, R.; Venkatakrishnan, R.

    2003-04-01

    This study has been carried out as part of the Corrective Measure Study (CMS) at a property owned by GlaxoSmithKline in Research Triangle Park, North Carolina, USA. The study area is located in the Durham subbasin of the Deep River Triassic Basin and is underlain by interbedded siltstone and sandstone sequences. Groundwater underlying portions of the site has been impacted by historical industrial activities conducted by previous owners; groundwater contaminants consist mainly of chlorinated volatile organic compounds. Golder conducted an initial review of potentially applicable remediation technologies and retained the Bimetallic Nanoscale Particle (BNP) technology for further evaluation. BNP consists of nanoscale particles (~ 60 nm) of zero valent iron (Fe0) with a trace coating of noble metal catalyst (palladium). The rapid destruction of a wide range of recalcitrant contaminants is based on a surface-catalyzed redox process where the contaminant serves as an electron acceptor and BNP as the electron donor and can be accomplished either in situ or ex situ (Wei-xian Zhang, 1997, 1999, 2000). This study presents the field demonstration of the BNP effectiveness to treat in-situ chlorinated VOCs in a complex fractured bedrock aquifer setting. During the field pilot test 11 kilograms of BNP mixed in water-based slurry were injected into the shallow bedrock groundwater suspected to contain dense non-aqueous phase liquids (DNAPLs). The results of the test indicated rapid treatment of chlorinated VOCs 7 m to 14 m around the injection well. In addition, the oxidation-reduction potential (ORP) and dissolved oxygen (DO) values have decreased and persisted at very low levels of -450 millivolts and less than 0.001 milligrams per liter, respectively, indicating favorable conditions for reductive dechlorination. Interpretation of pre- and post-test data on the in-situ microbiological community in the test area indicate that the changes in ORP and DO have resulted in inhibition

  15. ARSENIC REMOVAL

    EPA Science Inventory

    Presentation covered five topics; arsenic chemistry, best available technology (BAT), surface water technology, ground water technology and case studies of arsenic removal. The discussion on arsenic chemistry focused on the need and method of speciation for AsIII and AsV. BAT me...

  16. Characterization of TCE DNAPL and Dissolved Phase Transport in Karst Media

    NASA Astrophysics Data System (ADS)

    Carmona, M.; Padilla, I. Y.

    2015-12-01

    Trichloroethylene (TCE) contaminated sites are a threat to the environment and human health. Of particular concerns is the contamination of karst groundwater systems (KGWSs). Their heterogeneous character, rapid flow through conduits, high permeability zones, and strong storage capacity in the rock porous-matrix pose a high risk of exposure over large areas and temporal scales. To achieve effective remedial actions for TCE removal, it is important to understand and quantify the fate and transport process of trichloroethylene in these systems. This research studies the fate, transport, and distribution of TCE Non-Aqueous Phase Liquids (NAPLs) and associated dissolved species in KGWSs. Experiments are conducted in a karstified limestone physical model, a limestone rock mimicking a saturated confined karst aquifer. After injecting TCE solvent into a steady groundwater flow field, samples are taken spatially and temporally and analyzed for TCE NAPL and dissolved phases. Data analysis shows the rapid detection of TCE NAPL and high aqueous concentrations along preferential pathway, even at distances far away from the injection point. Temporal distribution curves exhibit spatial variations related to the limestone rock heterogeneity. Rapid response to TCE concentrations is associated with preferential flow paths. Slow response with long tailing indicates rate-limited diffusive transport in the rock matrix. Overall, results indicate that karstified limestone has a high capacity to rapidly transport pure and dissolved TCE along preferential flow paths, and to store and slowly release TCE over long periods of time.

  17. Hair removal.

    PubMed

    Haedersdal, Merete; Haak, Christina S

    2011-01-01

    Hair removal with optical devices has become a popular mainstream treatment that today is considered the most efficient method for the reduction of unwanted hair. Photothermal destruction of hair follicles constitutes the fundamental concept of hair removal with red and near-infrared wavelengths suitable for targeting follicular and hair shaft melanin: normal mode ruby laser (694 nm), normal mode alexandrite laser (755 nm), pulsed diode lasers (800, 810 nm), long-pulse Nd:YAG laser (1,064 nm), and intense pulsed light (IPL) sources (590-1,200 nm). The ideal patient has thick dark terminal hair, white skin, and a normal hormonal status. Currently, no method of lifelong permanent hair eradication is available, and it is important that patients have realistic expectations. Substantial evidence has been found for short-term hair removal efficacy of up to 6 months after treatment with the available systems. Evidence has been found for long-term hair removal efficacy beyond 6 months after repetitive treatments with alexandrite, diode, and long-pulse Nd:YAG lasers, whereas the current long-term evidence is sparse for IPL devices. Treatment parameters must be adjusted to patient skin type and chromophore. Longer wavelengths and cooling are safer for patients with darker skin types. Hair removal with lasers and IPL sources are generally safe treatment procedures when performed by properly educated operators. However, safety issues must be addressed since burns and adverse events do occur. New treatment procedures are evolving. Consumer-based treatments with portable home devices are rapidly evolving, and presently include low-level diode lasers and IPL devices.

  18. Equilibrium, kinetic and mass transfer studies and column operations for the removal of arsenic(III) from aqueous solutions using acid treated spent bleaching earth.

    PubMed

    Mahramanlioglu, M; Güçlü, K

    2004-09-01

    In the present study, a new adsorbent was produced from spent bleaching earth by H2SO4 impregnation method. The sorption of arsenic(III) by acid treated spent bleaching earth was studied to examine the possibility of utilizing this material in water treatment systems. The effect of time, pH, initial concentration, temperature on the adsorption of arsenic(III) was studied. Maximum adsorption was found to occur at pH 9.0. The adsorption process followed the first order Lagergren equation. Mass transfer coefficients and rate constants of in