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Artykuły w czasopismach na temat "Liquides denses en phase non aqueuse (DNAPL)"
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Valletti, Nadia, Marcello A. Budroni, Istvan Lagzi, Nadia Marchettini, Margarita Sanchez-Dominguez i Federico Rossi. "Interfacial Mass Transfer in Trichloroethylene/Surfactants/ Water Systems: Implications for Remediation Strategies". Reactions 2, nr 3 (3.09.2021): 312–22. http://dx.doi.org/10.3390/reactions2030020.
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The fate of dense non-aqueous phase liquids (DNAPLs) in the environment and the consequential remediation problems have been intensively studied over the last 50 years. However, a scarce literature is present about the mass transfer at the DNAPL/water interface. In this paper, we present a fast method for the evaluation of the mass transfer performance of a surfactant that can easily be employed to support an effective choice for the so-called enhanced remediation strategies. We developed a lab-scale experimental system modelled by means of simple ordinary differential equations to calculate the mass transfer coefficient (K) of trichloroethylene, chosen as representative DNAPL, in the presence and in the absence of two ethoxylated alcohols belonging to the general class of Synperonic surfactants. Our findings revealed that it exists an optimal surfactant concentration range, where K increases up to 40% with respect to pure water.
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Feo, Alessandra, Riccardo Pinardi, Andrea Artoni i Fulvio Celico. "Three-Dimensional High-Precision Numerical Simulations of Free-Product DNAPL Extraction in Potential Emergency Scenarios: A Test Study in a PCE-Contaminated Alluvial Aquifer (Parma, Northern Italy)". Sustainability 15, nr 12 (6.06.2023): 9166. http://dx.doi.org/10.3390/su15129166.
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Chlorinated organic compounds are widespread aquifer contaminants. They are known to be dense non-aqueous phase liquids (DNAPLs). Therefore, they are denser than water and immiscible with other fluids. Their migration into the environment in variably saturated zones can cause severe damage. For this reason, optimizing those actions that minimize the negative impact of these compounds in the subsurface is essential. This paper presented a numerical model simulating the free-product DNAPL migration and extraction through a purpose-designed pumping well in a potential emergency scenario. The numerical simulations were performed using CactusHydro, a numerical code that uses a high-resolution shock-capturing flux conservative method to resolve the non-linear coupled partial differential equations of a three-phase immiscible fluid flow recently proposed in the literature, including the contaminant extraction at the base of the aquifer. We investigated the temporal (and spatial) evolution of its migration in the Parma (Northern Italy) porous alluvial aquifer following the saturation contour profiles of the three-phase fluid flow in variably saturated zones. The results indicated that this numerical approach can simulate the contaminant migration in the subsurface and the pumping of the free-product from a well screened at the base of the aquifer system. Moreover, the simulation showed the possibility of recovering about two-thirds of the free-product, in agreement with the scientific literature.
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Jha, Shibani, i M. S. Mohan Kumar. "Multiphase models for simulating hot and slightly miscible DNAPL (dense non-aqueous phase fluids) in a saturated rock fracture under deformation". Water Science and Technology 59, nr 4 (1.02.2009): 755–62. http://dx.doi.org/10.2166/wst.2009.023.
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In the present study a two dimensional model is first developed to show the behaviour of dense non-aqueous phase liquids (DNAPL) within a rough fracture. To consider the rough fracture, the fracture is imposed with variable apertures along its plane. It is found that DNAPL follows preferential pathways. In next part of the study the above model is further extended for non-isothermal DNAPL flow and DNAPL-water interphase mass transfer phenomenon. These two models are then coupled with joint deformation due to normal stresses. The primary focus of these models is specifically to elucidate the influence of joint alteration due to external stress and fluid pressures on flow driven energy transport and interphase mass transfer. For this, it is assumed that the critical value for joint alteration is associated with external stress and average of water and DNAPL pressures in multiphase system and the temporal and spatial evolution of joint alteration are determined for its further influence on energy transport and miscible phase transfer. The developed model has been studied to show the influence of deformation on DNAPL flow. Further this preliminary study demonstrates the influence of joint deformation on heat transport and phase miscibility via multiphase flow velocities. It is seen that the temperature profile changes and shows higher diffusivity due to deformation and although the interphase miscibility value decreases but the lateral dispersion increases to a considerably higher extent.
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Cheng, Zhou, Guoping Lu, Ming Wu, Yanru Hao, Cehui Mo, Qusheng Li, Jianfeng Wu, Jichun Wu i Bill X. Hu. "The Effects of Spill Pressure on the Migration and Remediation of Dense Non-Aqueous Phase Liquids in Homogeneous and Heterogeneous Aquifers". Sustainability 15, nr 17 (30.08.2023): 13072. http://dx.doi.org/10.3390/su151713072.
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The spill pressure of the contaminant source is an important factor affecting the amount, location, form, and behavior of the dense non-aqueous phase liquids (DNAPLs) that plume in a contaminated subsurface environment. In this study, perchloroethylene (PCE) infiltration, distribution and, remediation via a surfactant-enhanced aquifer remediation (SEAR) technique for a PCE spill event are simulated to evaluate the effects of the spill pressure of the contaminant source on the DNAPLs’ behavior in two-dimensional homogeneous and heterogeneous aquifers. Five scenarios with different spill pressures of contamination sources are considered to perform the simulations. The results indicate that the spill pressure of the contaminant source has an obvious influence on the distribution of DNAPLs and the associated efficiency of remediation in homogeneous and heterogeneous aquifers. As the spill pressure increases, more and more contaminants come into the aquifer and the spread range of contamination becomes wider and wider. Simultaneously, the remediation efficiency of contamination also decreases from 93.49% to 65.90% as the spill pressure increases from 33.0 kPa to 41.0 kPa for a heterogeneous aquifer with 200 realizations. The simulation results in both homogeneous and heterogeneous aquifers show the same influence of the spill pressure of the contaminant source on PCE behaviors in the two-dimensional model. This study indicates that the consideration of the spill pressure of the contaminant sources (such as underground petrol tanks, underground oil storage, underground pipeline, and landfill leakage) is essential for the disposal of contaminant leakage in the subsurface environment. Otherwise, it is impossible to accurately predict the migration and distribution of DNAPLs and determine the efficient scheme for the removal of contaminant spills in groundwater systems.
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Iravani, Mohammad Ali, Jacques Deparis, Hossein Davarzani, Stéfan Colombano, Roger Guérin i Alexis Maineult. "Complex Electrical Resistivity and Dielectric Permittivity Responses to Dense Non-aqueous Phase Liquids' Imbibition and Drainage in Porous Media: A Laboratory Study". Journal of Environmental and Engineering Geophysics 25, nr 4 (grudzień 2020): 557–67. http://dx.doi.org/10.32389/jeeg20-050.
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The effective techniques for remediation of sites polluted by dense non-aqueous phase liquids (DNAPLs) remains a challenge. Among the various technical monitoring methods, there is an increasing interest in studying the geophysical characteristics of contaminated soils, as indicators of the progress in clean-up programs. This work sought to investigate the variation of the electrical complex resistivity and the relative permittivity by analyzing the results obtained from spectral induced polarization (SIP) and time domain reflectometry (TDR). Different series of measurements during drainage and imbibition of DNAPLs in porous media were done to validate the clean-up process on sites polluted by DNAPLs. Therefore, a methodology based on laboratory work was designed and carried out to study the electrical complex resistivity (both in magnitude and phase) in the frequency range 0.183 Hz to 20 kHz, and the relative dielectric permittivity at 70 MHz. The experiments were done on small 1D cells. In these cells, glass beads were used as a porous medium. Two different fluid couples, i.e., coal tar (CT)/water and canola oil (CO)/salty ethanol (SE), were used to produce two-phase flow. Our findings highlight that due to the high resistivity of CO and CT, an increase in water saturation led to decrease in amplitude and phase. Saturation change of SE had the same effect on resistivity but no relationship was found for phase and saturation for the mixture CO and SE. It is also showed that the complex resistivity and relative permittivity measurements were compatible with generalized Archie's law and complete complex refractive index method (CRIM) model as two empirical models for defining the correlation between the electrical resistivity, relative permittivity, and saturation of each phase in the multiphase porous medium.
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ROSSABI, J. "Recent Advances in Characterization of Vadose Zone Dense Non-Aqueous Phase Liquids (DNAPL) in Heterogeneous Media". Environmental and Engineering Geoscience 9, nr 1 (1.02.2003): 25–36. http://dx.doi.org/10.2113/9.1.25.
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Chu, Haibo, i Wenxi Lu. "Adaptive Kriging surrogate model for the optimization design of a dense non-aqueous phase liquid-contaminated groundwater remediation process". Water Supply 15, nr 2 (25.10.2014): 263–70. http://dx.doi.org/10.2166/ws.2014.108.
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The optimization model needs to call the simulation model to calculate the response under different conditions for many times, and this is computationally expensive and time-consuming. To solve this problem, surrogate models can be used to yield insight into the functional relationship between the design variables and the responses, instead of simulation models in the optimization. In this paper, an integrated optimization method based on adaptive Kriging surrogate models was proposed and applied to the cost optimization of a surfactant enhanced aquifer remediation process for dense non-aqueous phase liquids (DNAPLs). First, the initial samples were created by Latin hypercube sampling, and then the responses corresponding to the initial samples were computed by a simulation model. The initial Kriging model was derived through these samples. Secondly, the adaptive Kriging surrogate model was proposed based on updating initial Kriging with new samples via infill sampling criteria. The results showed that it had improved the accuracy of the surrogate model, and the added samples had provided more information about the simulation model than the common samples. Even with the same number of samples, the adaptive Kriging surrogate model performed better than the common Kriging surrogate model, which was built only once. What's more, the integrated approach not only greatly reduced the computational burden, but also determined the actual optimal DNAPLs remediation strategy.
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Huang, Wei Hsiang, Yih Terng Sheu, Po Jen Lien, Yu Sung Hsiao i Chih Ming Kao. "Investigation and Remedial Approach Development for a TCE Spill Site: A Case Study". Advanced Materials Research 912-914 (kwiecień 2014): 1884–87. http://dx.doi.org/10.4028/www.scientific.net/amr.912-914.1884.
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A trichloroethene (TCE) plume has been discovered inside an industrial park located in Taiwan. The objectives of this study were to characterize the solvent spill site and prepare a corrective action plan (CAP) for site remediation. The following tasks have been performed under Taiwan Soil and Groundwater Remediation Act corrective action: (1) geophysical survey to verify the existence and fate of all potential contaminant sources in the vicinity of the avionics repair shop; (2) soil-gas survey and soil/groundwater analyses to delineate the lateral and vertical extent of contaminants in the subsurface; (3) application of field screening techniques to determine the presence of dense, non-aqueous-phase liquids (DNAPLs); (4) contaminant transport modeling; (5) evaluation of the remedial options, conduction of cost analysis, and selection of the optimal treatment system. Results from the site characterization indicate that an extended TCE plume existed in site groundwater, which needs to be contained and remediated. A two-phase remedial approach has been developed. Phase I was to contain the existing dissolved groundwater plume in the surficial aquifer and initiate mass removal of DNAPLs. Phase II was to conduct feasibility studies and possibly test surfactant washing and biobarrier techniques.
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Dubé, Jean-Sébastien, Rosa Galvez-Cloutier i Thierry Winiarski. "Heavy metal transport in soil contaminated by residual light non-aqueous phase liquids (LNAPLs)". Canadian Geotechnical Journal 39, nr 2 (1.04.2002): 279–92. http://dx.doi.org/10.1139/t01-113.
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This paper presents an experimental study on mixed soil contamination, more specifically on heavy metal behaviour in soil contaminated by residual non-aqueous phase liquids (NAPLs). Remediation of mixed contaminated sites is a complex technical goal because of the presence of physically and chemically different contaminants and potential interactions between them. Commonly encountered contaminants in mixed contaminated soils include light and dense organic liquids (LNAPLs, DNAPLs) and heavy metals. This study investigated interactions between three residual LNAPLs and three heavy metals (Cd, Cu, Pb) in a carbonated soil. The objectives of the study were to (i) establish the presence of interactive processes in the behaviour of the contaminants, with a focus on the influence of residual LNAPL on heavy metal transport and retention; and (ii) determine the nature of these interactions. Results showed that the LNAPL having the highest residual saturation enhanced heavy metal mobility and decreased heavy metal retention by the soil. On the other hand, the geochemical distribution of heavy metals was not significantly modified by chemical interactions with the residual LNAPLs. Specific modifications of Pb and Cu geochemical distributions rather appeared to be the result of modifications of soil hydrodynamics by residual LNAPL.Key words: contaminated soil, mixed contamination, heavy metals, LNAPL, preferential flow, contaminant mobility.
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Stewart, Mark, i Loren North. "A borehole geophysical method for detection and quantification of dense, non-aqueous phase liquids (DNAPL) in saturated soils". Journal of Applied Geophysics 60, nr 2 (październik 2006): 87–99. http://dx.doi.org/10.1016/j.jappgeo.2005.12.004.
Pełny tekst źródłaRozprawy doktorskie na temat "Liquides denses en phase non aqueuse (DNAPL)"
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Colombano, Stéfan. "Improvement of the recovery of heavy chlorinated organic compounds in saturated porous media by thermal and chemical enhancements : experimental and two-phase flow modeling approaches". Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC2032.
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La pollution des eaux souterraines par des composés organochlorés constitue un problème majeur. En effet, ces polluants, particulièrement toxiques, dégradent durablement les sols et les eaux souterraines. Leur dispersion (par solubilisation et volatilisation) à partir des sources de pollution peut générer des panaches de contamination importants. La récupération de ces composés sous forme de produit pur (DNAPL) est principalement basée sur les techniques de pompage/traitement. Pour autant, cette technique est lente et ne permet pas de récupérer le DNAPL de manière efficace. Une quantité de DNAPL reste piégée dans le sol sous forme de saturation résiduelle (Srn). L’objectif de cette thèse est d'améliorer le rendement et la vitesse de récupération du DNAPL en utilisant les soutiens chimiques et thermiques au cours du pompage. L’augmentation de la température vise à diminuer la viscosité du DNAPL (et donc à augmenter sa mobilité) alors que l’ajout de surfactant vise à diminuer les forces capillaires qui piègent le DNAPL. Des expérimentations à l’échelle du laboratoire (basées notamment sur des suivis de permittivités, résistivités électriques et densités optiques) et une modélisation multiphasique ont été réalisées afin de pouvoir quantifier les effets de ces soutiens. Le chauffage du DNAPL, réalisé jusqu’à 50 °C (afin d’éviter la volatilisation), diminue la viscosité par un facteur 2. L’ajout d’un surfactant, le Sodium Dodecyl Benzene Sulfonate-SDBS, à sa Concentration Micellaire Critique (afin d’éviter la solubilisation du DNAPL) diminue la tension interfaciale par un facteur 12. Les essais de drainage-imbibition ont été réalisés dans des cellules 1D afin d’obtenir les courbes de rétention du système diphasique (pression capillaire en fonction de la saturation en eau). Les diminutions des Srn obtenues avec le SDBS sont de 28% pour les billes de verre (BV) de 0,5 mm de diamètre et 46% pour les BV de 0,1 mm. Aucune amélioration significative du rendement épuratoire a été obtenue avec le chauffage. Les courbes ont été calées avec le modèle de van Genuchten - Mualem dans le but de fournir les données pour la modélisation. Les expériences de drainage-imbibition ont été réalisées dans des colonnes 1D pour caractériser les écoulements diphasiques (notamment le déplacement de l'interface DNAPL-eau en fonction des pressions appliquées). Le modèle d'écoulement diphasique a été réalisé avec la formulation de pression-pression (à l'aide de COMSOL Multiphysics®). La modélisation des volumes récupérés et du déplacement de l’interface sont en accord avec les résultats expérimentaux. Les rendements épuratoires avec les soutiens chimiques et thermiques étaient du même ordre de grandeur que pour les cellules 1D. Des essais de pompage ont été effectués dans un bac 2D à différents débits avec les BV de 0,5 mm et 0,1 mm. Les expériences ont également été réalisées avec et sans soutien. Les modélisations ont été comparées à l'interprétation d'images (basée sur l'étalonnage de la densité optique). Les valeurs expérimentales sont en adéquation avec les valeurs modélisées. Les rapports VDNAPL,chimique/VDNAPL, référence pour des débits lents et élevés, étaient en moyenne respectivement de 2,90 et 1,40 pour les BV de 0,5 mm et, de 1,37 et 1,18 pour les BV de 0,1 mm. Le chauffage n'a aucun effet bénéfique sur la récupération du DNAPL. Les mesures indirectes des saturations en eau (Sw) pour les expériences 1D ou 2D aboutissent aux résultats suivants: i. les permittivités mesurées sont très proches des valeurs modélisées avec le modèle de CRIM ; ii. les modélisations des résistivités électriques avec la loi d’Archie sont moins probantes ; iii. les densités optiques permettent d’estimer Sw avec précision. A l’échelle terrain, la combinaison des suivis avec la résistivité électrique (qui permet d’avoir une vision intégratice) et la permittivité (qui fournit des données précises mais spatialement limitées), permettrait de mieux quantifier les SrnGroundwater pollution by chlorinated organic compounds is a major problem. Actually, these particularly toxic pollutants, permanently degrade soil and groundwater quality. Their dispersion (by solubilization and volatilization) from the pollution source zone can generate large contaminants plumes.Chlorinated organic compounds are recovered as pure product (Dense Non-Aqueous Phase Liquids-DNAPL) mainly using pump/treat technologies. However, these technologies are time-consuming and do not recover the pure product in an efficient way. A significant amount of DNAPL remains trapped in soil as residual saturation (Srn). The objective of this PhD project was to enhance DNAPL recovery rate and yield using chemical and thermal enhancements during the pumping process. Temperature increases aimed to reduce the viscosity of DNAPL (and therefore to increase its mobility) while the addition of surfactant aimed to reduce the capillary forces that trap the DNAPL. Experiments at the laboratory scale (based on monitoring of permittivities, electrical resistivities and optical densities) and two-phase flow modeling were performed to quantify the effects of these enhancements. Heating the DNAPL up to 50 °C (to avoid volatilization) decreases the viscosity by a factor of two. The addition of surfactant, Sodium Dodecyl Benzene Sulfonate-SDBS, at its Critical Micelle Concentration (to prevent DNAPL solubilization) decreases interfacial tensions by a factor of 12. Drainage-imbibition experiments were carried out in 1D cells to obtain the retention curves of the two-phase system (capillary pressure as a function of water saturation). The decreases of Srn obtained with SDBS were 28% for 0.5 mm glass beads (GB) diameter and 46% for 0.1 mm GB. We reported no significant improvement in the remediation yield with thermal enhancement. The curves were fitted with the van Genuchten – Mualem model to generate data for modeling.Drainage-imbibition experiments were carried out in 1D columns to characterize two-phase flow (and in particular the displacement of the DNAPL-water interface according to the pressures applied). The two-phase flow model used a pressure-pressure formulation (using COMSOL Multiphysics®). The modeling of recovered volumes and the displacement of the interface agreed with the experimental results. The remediation yields with chemical and thermal enhancements were of the same order of magnitude as those reported in 1D cells. For 2D tank experiments, pumping was performed at different flow rates with 0.5 mm and 0.1 mm GB. The experiments were also performed with and without enhancement. Models were compared with image interpretation (based on the optical density calibration). Comparing experimental and modeled values shows that the model fitted well with the experiments. The VDNAPL, chemical/VDNAPL, reference ratios were for low and high flow rates on average respectively 2.90 and 1.40 for 0.5 mm GB and 1.37 and 1.18 for 0.1 mm GB. Thermal enhancement had no beneficial effect on DNAPL recovery rate or yield.Indirect measurements of water saturations (Sw) for 1D or 2D experiments yielded the following results: i. the measured permittivities were very similar to the values modeled with the CRIM model; ii. modeling of electrical resistivities with Archie's Law was less accurate; iii. optical densities allow accurate Sw estimation. At field scale, the combination of monitoring both electrical resistivities (which provide a global picture) and permittivities (which provide precise but spatially limited data), is expected to provide Srn data
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Steele, Adrian. "DNAPL migration in variable aperture fractures : the development of a site investigation tool to measure fracture apertures applicable to DNAPL migration in situ in the Dumfries Aquifer, southwest Scotland". Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370003.
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Iravani, Mohammad Ali. "Monitoring the remediation of coal tar in contaminated soil using electro-geophysical methods". Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS330.
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Au cours des deux dernières décennies, la dépollution et la surveillance des sites pollués sont devenus une question sociétale importante. Les techniques classiques de surveillance par piézomètres et piézairs ne suffisent pas pour suivre les changements caractéristiques dans le sous-sol de ces sites en raison de leur caractère ponctuel. Ainsi l’interprétation de données géophysiques acquises lors de la surveillance de tels sites est un outil pour la dépollution de leurs sols. Les propriétés géophysiques sont des paramètres clés dans la validation des méthodes de dépollution des sols contaminés par des produits chimiques organiques et industriels, comme les hydrocarbures lourds, DNAPL (‘Dense Non-Aqueous Phase Liquids’ en anglais). Parmi les techniques géophysiques pouvant être utilisées pour suivre les propriétés physiques des sites contaminés, les méthodes électriques et électromagnétiques se sont révélées être des techniques de surveillance fiables fournissant des informations sur la résistivité électrique et la permittivité diélectrique reliées aux propriétés physiques et hydrodynamiques du milieu. L’objectif principal de cette thèse est d’évaluer la capacité des méthodes électromagnétiques afin de suivre le processus de dépollution dans des sols contaminés par des DNAPL, via l’utilisation en laboratoire des méthodes de SIP (‘Spectral Induced Polarization’ en anglais, polarisation provoquée spectrale ou dans le domaine fréquentiel en français) et TDR (‘Time Domain Reflectometry’ en anglais) dans des milieux poreux contaminés, ces méthodes mesurant ces propriétés électromagnétiquesDuring the past two decades, the remediating and monitoring of polluted sites have become an important issue. Among all geophysical techniques, electrical methods showed their ability to monitor clean-up programs in these sites. Spectral induced polarization (SIP) technique is a method in near surface geophysics to measure complex electrical resistivity of a medium in the frequency domain. The other geophysical method was used is time domain reflectometry (TDR) that has been developed to measure relative dielectric permittivity, water content and temperature in homogeneous or heterogeneous porous media. This thesis is a challenge to evaluate efficiency and potential of SIP and TDR for a long-term monitoring of dense non-aqueous phase liquids (DNAPLs) recovery in contaminated porous media in the laboratory. Different sets of experiments designed to study the impacts of temperature and saturation changes on electrical complex resistivity and relative permittivity of saturated porous media on isothermal and non-isothermal conditions were examined in different 1D columns. The measurements were made with different couples of pollutants and fluids (i.e. coal tar/water, chlorinated solvent/water and canola oil/salty ethanol) in porous media simulated with glass beads of 1 mm diameter.Our findings concerning to temperature and saturation change show that experimental data of relative permittivity and complex resistivity obey empirical models validating our experimental setup and protocol. The results from the laboratory measurements will be used in the real conditions in field measurements in a remediation program
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Adams, Kortney A. (Kortney Ada) 1975. "Investigation into dense non-aqueous phase liquid (DNAPL) transport and remediation in vertical fractures". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/80645.
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Pang, Ti Wee. "DNAPL remediation of fractured rock evaluated via numerical simulation". Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4151.
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Fractured rock formations represent a valuable source of groundwater and can be highly susceptible to contamination by dense, non-aqueous phase liquids (DNAPLs). The goal of this research is to evaluate the effectiveness of three accepted remediation technologies for addressing DNAPL contamination in fractured rock environments. The technologies under investigation in this study are chemical oxidation, bioremediation, and surfactant flushing. Numerical simulations were employed to examine the performance of each of these technologies at the field scale. The numerical model DNAPL3D-RX, a finite difference multiphase flow-dissolution-aqueous transport code that incorporates RT3D for multiple species reactions, was modified to simulate fractured rock environments. A gridding routine was developed to allow the model to accurately capture DNAPL migration in fractures and aqueous phase diffusion gradients in the matrix while retaining overall model efficiency. Reaction kinetics code subroutines were developed for each technology so as to ensure the key processes were accounted for in the simulations. The three remedial approaches were systematically evaluated via simulations in two-dimensional domains characterized by heterogeneous orthogonal fracture networks parameterized to be representative of sandstone, granite, and shale. Each simulation included a DNAPL release at the water table, redistribution to pools and residual, followed by 20 years of ‘ageing’ under ambient gradient conditions. Suites of simulations for each technology examined a variety of operational issues including the influence of DNAPL type and remedial fluid injection protocol. Performance metrics included changes in mass flux exiting, mass destruction in the matrix versus the fractures, and percentage of injected remedial fluid interacting with the target contaminant. The effectiveness of the three remediation technologies covered a wide range; the mass of contaminants destroyed were found to range from 15% to 99.5% of the initial mass present. Effectiveness of each technology was found to depend on a variety of critical factors particular to each approach. For example, in-situ chemical oxidation was found to be limited by the organic material present in the matrix of the rocks, while the efficiency of enhanced bioremediation was found to be related to factors such as the location of indigenous bacteria present in the domain and rate of bioremediation. In the chemical oxidation study, the efficiency of oxidant consumption was observed to be poor across the suite of scenarios, with greater than 90% of the injected permanganate consumed by natural oxidant demand. This study further revealed that the same factors that contributed to forward diffusion of contaminants prior to treatment are critical to this remediation method as they can determine the extent of contaminant destruction during the injection period. Bioremediation in fractured rock was demonstrated to produce relatively good results under robust first-order decay rates and active microorganisms throughout the fractures and matrix. It was demonstrated that under ideal conditions, of the total initial mass present, up to 3/4 could be reduced to ethene, indicating bioremediation may be a promising treatment approach due to the effective penetration of electron donor into the matrix during the treatment period and the ongoing treatment that occurs after injection ceases. However, when indigenous bacteria was assumed to exist only within the fractured walls of sandstone, it was found that under the same conditions, the rate of dechlorination was 200 times less than the Base Case. Since the majority of the mass resided in the matrix, lack of bioremediation in the matrix significantly reduced the effectiveness of treatment. Surfactant treatment with Tween-80 was proven to be a relatively effective technique in enhanced solubilisation of DNAPL from the fractures within the domain. However, by comparing the aqueous and sorbed mass at the start and end of the Treatment stage, it is revealed that surfactant treatment is not efficient in removing these masses that reside within the matrix. Furthermore, DNAPLs identified in dead end vertical fractures were found to remain in the domain by the end of the simulations across all scenarios studied; indicating that the injected surfactant experiences difficulty in accessing DNAPLs entrapped in dead end fractures. Altogether, the results underscore the challenge of restoring fractured rock aquifers due to the field scale limitations on sufficient contact between remedial fluids and in situ contaminants in all but the most ideal circumstances.
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Hill, Katherine I. "DNAPL migration in single fractures : issues of scale, aperture variability and matrix diffusion". University of Western Australia. School of Environmental Systems Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0003.
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[Truncated abstract] To date, many subsurface contaminant modelling studies have focused on increasing model complexity and measurement requirements to improve model accuracy and widen model application. However, due to the highly complex and heterogeneous nature of flow in the subsurface, the greater benefit in model development may lie in decreasing complexity by identifying key processes and parameters, simplifying the relationships that exist between them, and incorporating these relationships into simple models that recognise or quantify the inherent complexity and uncertainty. To address this need, this study aims to identify and isolate the key processes and parameters that control dense nonaqueous phase liquid (DNAPL) and aqueous phase migration through single, onedimensional fractures. This is a theoretical representation which allows the study of processes through conceptual and mathematical models. Fracture systems typically consist of multiple two-dimensional fractures in a three-dimensional network; however, these systems are computationally and conceptually demanding to investigate and were outside of the scope of this study. This work initially focuses on DNAPL migration in single, one-dimensional fractures. The similitude techniques of dimensional and inspectional analysis are performed to simplify the system and to develop breakthrough time scale factors. This approach relies heavily on the limitations of the equation used for the analysis and on the difficulty in representing variable aperture scenarios. The complexity of the conceptual model is then increased by embedding the fracture in a two-dimensional, porous matrix. ... These tools can be readily applied by the field investigator or computer modeller to make order-of-magnitude estimates of breakthrough times, reduce or target measurement requirements, and lessen the need to employ numerical multiphase flow models. To determine the implications of the results found in the one-dimensional studies to applications at the field scale, the complexity of the conceptual model was increased to a single, two-dimensional, planar fracture embedded in a three-dimensional porous matrix. The focus of this study was not DNAPL breakthrough times but the relative importance and interaction of different mass transport processes and parameters on plume migration and evolution. Observations clearly show that estimates of the size, location and concentration of the plume is highly dependent on the geologic media, the temporal and spatial location and resolution of measurements, and on the history, mass and location of the DNAPL source. In addition, the processes controlling mass transport (especially matrix diffusion and back diffusion) act in combination at the field scale in ways not always expected from an analysis of processes acting individually at smaller spatial and temporal scales. Serious concerns over the application of the common '1% Rule of Thumb' to predict DNAPL presence and the use of remediation efforts that rely largely on natural attenuation are raised. These findings have major implications for the field worker and computer modeller, and any characterisation, monitoring or remediation program development needs to be sensitive to these findings.
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Li, Xuan. "In Situ Chemical Oxidation Schemes for the Remediation of Ground Water and Soils Contaminated by Chlorinated Solvents". Connect to this title online, 2002. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1023289254.
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Thesis (Ph. D.)--Ohio State University, 2002.Title from first page of PDF file. Document formatted into pages; contains xv, 179 p.; also contains graphics (some col.). Includes abstract and vita. Advisor: Franklin W. Schwartz, Dept. of Geosciences. Includes bibliographical references (p. 172-179).
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Mwamba, Olivier. "Investigating the toxicity of Dense Non-aqueous Phase Liquids (DNAPL) in contaminated groundwater". Thesis, 2009. http://hdl.handle.net/10210/2698.
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M.Tech. Biomedical TechnologyPrevious studies have reported on the potential health risks associated with direct contact with chemicals (such as DNAPLs) via inhalation or drinking of contaminated groundwater. Dense Non-Aqueous Phase Liquids (DNAPLs) enter into groundwater through incorrect storage or disposal and pose risk to human health. Industrialization contributes considerably to contamination of ground water with waste disposal practices leading to the deposition of hazardous waste at geologically/hydro-geologically unsuitable locations. Many hazardous chemicals found their way into groundwater by this mean and might cause problems if ingested in drinking water. Most of these compounds undergo only limited degradation in the subsurface, and persist for long periods of time while slowly releasing soluble organic constituents that present hazardous health effects (both toxic and non-toxic) to humans.
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Robertson, Natasha. "Measuring total toxicity and genotoxic potential of ground-waterborne Dense Non-aqueous Phase Liquids (DNAPL)". Thesis, 2010. http://hdl.handle.net/10210/3120.
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M. Tech.Background: Groundwater is essential for many human activities, especially as a source of drinking water. Contaminated groundwater threatens many valuable water resources which may have adverse human health consequences. Groundwater contamination often goes unnoticed as it occurs underground and it is often impossible to, and often very expensive to rehabilitate. Groundwater pollution originating from industrial sites is a general problem in many industrialized countries, but also in developing countries such as South Africa. Among the various types of groundwater contamination, DNAPL (Dense Non-Aqueous Phase Liquids) contamination is a common one. A generic test for determining DNAPL contamination in water and their adverse effects on human health that consume this water does not exist. This study was aimed, by using two known immunoassays, to asses the toxicity and DNA damaging potential, using known techniques, of two index DNAPL and untested groundwater from newly drilled boreholes in areas suspected of DNAPL contamination. Objectives: To compile a DNAPL guideline based the use of index chemicals (Tricloroethylene [TCE] and Aroclor® 1254 [ARO]) to determine the high-end values and a series of reference (non-contaminated ground, and other treated waters) samples used to determine low-end values. PBMC were exposed to these samples and the test reactions for cytotoxicity and DNA damage measured. The methodology was then applied to groundwaters taken from an industrial site. This was to establish the health effects of these waters as well as determining whether they had DNAPL contamination.
Książki na temat "Liquides denses en phase non aqueuse (DNAPL)"
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Interstate Technology and Regulatory Cooperation Work Group. DNAPLs/Chemical Oxidation Work Team. Dense non-aqueous phase liquids (DNAPLs): Review of emerging characterization and remediation technologies. United States]: ITRC, 2000.
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Su, Chunming, Robert W. Puls, Thomas A. Krug, Mark T. Watling, Suzanne K. O'Hara, Jacqueline W. Quinn i Nancy E. Ruiz. "Long-Term Performance Evaluation of Groundwater Chlorinated Solvents Remediation Using Nanoscale Emulsified Zerovalent Iron at a Superfund Site". W Waste Management, 1352–71. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-1210-4.ch061.
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This chapter addresses a case study of long-term assessment of a field application of environmental nanotechnology. Dense Non-Aqueous Phase Liquid (DNAPL) contaminants such as Tetrachloroethene (PCE) and Trichloroethene (TCE) are a type of recalcitrant compounds commonly found at contaminated sites. Recent research has focused on their remediation using environmental nanotechnology in which nanomaterials such as nanoscale Emulsified Zerovalent Iron (EZVI) are added to the subsurface environment to enhance contaminant degradation. Such nanoremediation approach may be mostly applicable to the source zone where the contaminant mass is the greatest and source removal is a critical step in controlling the further spreading of the groundwater plume. Compared to micro-scale and granular counterparts, NZVI exhibits greater degradation rates due to its greater surface area and reactivity from its faster corrosion. While NZVI shows promise in both laboratory and field tests, limited information is available about the long-term effectiveness of nanoremediation because previous field tests are mostly less than two years. Here an update is provided for a six-year performance evaluation of EZVI for treating PCE and its daughter products at a Superfund site at Parris Island, South Carolina, USA. The field test consisted of two side-by-side treatment plots to remedy a shallow PCE source zone (less than 6 m below ground surface) using pneumatic injection and direct injection, separately in October 2006. For the pneumatic injections, a two-step injection procedure was used. First, the formation was fluidized by the injection of nitrogen gas alone, followed by injection of the EZVI with nitrogen gas as the carrier. In the pneumatic injection plot, 2,180 liters of EZVI containing 225 kg of iron (Toda RNIP-10DS), 856 kg of corn oil, and 22.5 kg of surfactant were injected to remedy an estimated 38 kg of chlorinated volatile compounds (CVOC)s. Direct injections were performed using a direct push rig. In the direct injection plot, 572 liters of EZVI were injected to treat an estimated 0.155 kg of CVOCs. Visual inspection of collected soil cores before and after EZVI injections shows that the travel distance of EZVI was dependent on the method of delivery with pneumatic injection achieving a greater distance of 2.1 m than did direct injection reaching a distance of 0.89 m. Significant decreases in PCE and TCE concentrations were observed in downgradient wells with corresponding increases in degradation products including significant increases in ethene. In the pneumatic injection plot, there were significant reductions in the downgradient groundwater mass flux values for chlorinated ethenes (>58%) and a significant increase in the mass flux of ethene (628%). There were significant reductions in total CVOCs mass (78%), which was less than an estimated 86% decrease in total CVOCs made at 2.5 years due to variations in soil cores collected for CVOCs extraction and determination; an estimated reduction of 23% (vs.63% at 2.5 years) in the sorbed and dissolved phases and 95% (vs. 93% at 2.5 years) reduction in the PCE DNAPL mass. Significant increases in dissolved sulfide, volatile fatty acids (VFA), and total organic carbon (TOC) were observed and dissolved sulfate and pH decreased in many monitoring wells. The apparent effective destruction of CVOC was accomplished by a combination of abiotic dechlorination by nanoiron and biological reductive dechlorination stimulated by the oil in the emulsion. No adverse effects of EZVI were observed for the microbes. In contrast, populations of dehalococcoides showed an increase up to 10,000 fold after EZVI injection. The dechlorination reactions were sustained for the six-year period from a single EZVI delivery. Repeated EZVI injections four to six years apart may be cost-effective to more completely remove the source zone contaminant mass. Overall, the advantages of the EZVI technology include an effective “one-two punch” of rapid abiotic dechlorination followed by a sustained biodegradation; contaminants are destroyed rather than transferred to another medium; ability to treat both DNAPL source zones and dissolved-phase contaminants to contain plume migration; ability to deliver reactants to targeted zones not readily accessible by conventional permeable reactive barriers; and potential for lower overall costs relative to alternative technologies such as groundwater pump-and-treat with high operation and maintenance costs or thermal technologies with high capital costs. The main limitations of the EZVI technology are difficulty in effectively distributing the viscous EZVI to all areas impacted with DNAPL; potential decrease in hydraulic conductivity due to iron corrosion products buildup or biofouling; potential to adversely impact secondary groundwater quality through mobilization of metals and production of sulfides or methane; injection of EZVI may displace DNAPL away from the injection point; and repeated injections may be required to completely destroy the contaminants.
Streszczenia konferencji na temat "Liquides denses en phase non aqueuse (DNAPL)"
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Power, Christopher, Jason Gerhard i Panos Tsourlos. "Geoelectrical monitoring of dense non-aqueous phase liquid (DNAPL) remediation: Numerical, experimental, and field studies". W First International Meeting for Applied Geoscience & Energy. Society of Exploration Geophysicists, 2021. http://dx.doi.org/10.1190/segam2021-3584111.1.
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Stewart, Mark, i Loren North. "A Geophysical Method for Detection and Quantification of Dense Non‐Aqueous Phase Liquids (DNAPL) in the Subsurface". W Symposium on the Application of Geophysics to Engineering and Environmental Problems 2003. Environment and Engineering Geophysical Society, 2003. http://dx.doi.org/10.4133/1.2923108.
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Stewart, Mark, i Loren North. "A Geophysical Method For Detection And Quantification Of Dense Non-Aqueous Phase Liquids (Dnapl) In The Subsurface". W 16th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems. European Association of Geoscientists & Engineers, 2003. http://dx.doi.org/10.3997/2214-4609-pdb.190.pos05.
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Power, C., P. Tsourlos, J. I. Gerhard i T. Dahlin. "Simulated Time-lapse DC-IP Monitoring of Dense Non-aqueous Phase Liquids (DNAPLs) - An Initial Approach". W 23rd European Meeting of Environmental and Engineering Geophysics. Netherlands: EAGE Publications BV, 2017. http://dx.doi.org/10.3997/2214-4609.201702030.
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Cross, Paul E., i Del Baird. "Phased Implementation of In Situ Chemical Oxidation for a Large TCE DNAPL Source Area at the Portsmouth Gaseous Diffusion Plant, USA". W The 11th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2007. http://dx.doi.org/10.1115/icem2007-7200.
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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.
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Neil John D'Cunha, Debasmita Misra, David L. Barnes i Gang Chen. "Reduction of Residual Dense Non-Aqueous Phase Liquids (DNAPL) in Groundwater Using Natural Freezing of Soils in Cold Regions in Combination with Microbial Polymer Gels". W 2004, Ottawa, Canada August 1 - 4, 2004. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2004. http://dx.doi.org/10.13031/2013.16206.
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Kosko, Nancy, Janet Gilman i Debbie White. "Performance-Based Acquisition: A Tool to Reduce Costs and Improve Performance at US Army Environmental Remediation Sites". W The 11th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2007. http://dx.doi.org/10.1115/icem2007-7050.
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The US Army, like most US federal and state environmental organizations, is faced with limited resources to conduct environmental work, an increasing workload, and challenges in achieving closeout of its environmental cleanup programs. In 2001, in an effort to incorporate proven private sector tools into federal cleanup programs, the Department of Defense (DoD) Business Initiative Council (BIC), initiated the use of Performance-Based Acquisition (PBA) for environmental cleanup. Since fiscal year 2000, the US Army Environmental Command (USAEC) has successfully awarded more than 55 performance-based contracts for environmental remediation. These contracts range in size from $500,000 to $52.4 million, and include closing properties (Base Realignment and Closure (BRAC)) and some of the US Army’s most complex active installations. The contracts address a range of activities including investigation through monitoring and site completion, as well as various technical challenges including dense non-aqueous phase liquids (DNAPL) in ground water, karst systems, munitions and explosives of concern, and biological agents. The contracts are most often firm-fixed price, and 50 percent of the contracts required contractors to purchase environmental insurance in the form of remediation stop loss insurance (also known as cleanup cost cap insurance). The USAEC has conducted continuous process improvement since inception of the initiative. This paper presents results of two studies that were conducted in 2005–2006 to determine what lessons learned can be applied to future activities and to measure performance of contractors currently executing work under the performance based contracts.
Raporty organizacyjne na temat "Liquides denses en phase non aqueuse (DNAPL)"
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Korte, N. E., S. C. Hall i J. L. Baker. Refinement of the Kansas City Plant site conceptual model with respect to dense non-aqueous phase liquids (DNAPL). Office of Scientific and Technical Information (OSTI), październik 1995. http://dx.doi.org/10.2172/117791.
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Jerome, K. M., B. B. Looney, F. Accorsi, M. Dingens i J. T. Wilson. Test plan for Geo-Cleanse{reg_sign} demonstration (in situ destruction of dense non-aqueous phase liquid (DNAPL)). Office of Scientific and Technical Information (OSTI), wrzesień 1996. http://dx.doi.org/10.2172/527482.
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