Download or read book A Numerical Investigation of Metabolic Reductive Dechlorination in DNAPL Source Zones written by John Anthony Christ and published by . This book was released on 2005 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among the most intractable environmental remediation problems are those involving the release of dense non-aqueous phase liquids (DNAPLs), such as chlorinated solvents, to the subsurface. Research efforts have focused on the use of numerical models to investigate reductions in contaminant concentrations due to partial mass removal and improvements in the performance of complementary source zone remediation technologies. Previous numerical investigations, however, have been limited to two-dimensional systems. Furthermore, a lack of models capable of simulating the most promising complementary technology, metabolic reductive dechlorination, has limited its application. This work developed and applied compositional multiphase numerical simulators to examine the influence of dimensionality (two-dimensions versus three-dimensions) on DNAPL source zone simulations and to investigate the benefits of stimulating metabolic reductive dechlorination at a chlorinated ethene-DNAPL contaminated site. Results from the dimensionality investigation showed that the simulation of DNAPL migration, entrapment, and dissolution in two dimensions provided reasonable approximations to the behavior simulated in three dimensions. Commonly employed saturation distribution and mass recovery metrics were approximately equivalent. Flux- averaged concentrations simulated in two dimensions, however, tended to be three to four times higher than those simulated in three dimensions. This difference was attributed to dilution at the down gradient boundary. An alternative metric, mass flux reduction, however, yielded better agreement.
Download or read book Development of Assessment Tools for Evaluation of the Benefits of DNAPL Source Zone Treatment written by and published by . This book was released on 2008 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its commencement in September 2002, SERDP Project ER-1293 has supported 4 doctoral students at three universities and resulted in over 40 conference proceedings/technical abstracts and over 20 peer-reviewed publications. These presentations and publications, as referenced in this final report, describe various aspects of the research investigations and tools that have been developed to enhance design and assessment of DNAPL source zone treatment. In general, research in ER-1293 has led to the development and validation of four important concepts: (i) partial source zone mass removal may result in substantial local concentration and mass flux reductions; (ii) potential remediation efficiency is closely linked to source zone architecture (ganglia to pool ratios); (iii) biostimulation and bioaugmentation approaches are feasible for treatment of DNAPL source zones; and (iv) the uncertainty in mass discharge ([M/T]) estimates can be quantified through application of geostatistical methods to field measurements. Major contributions of this research include (i) establishment that rates of metabolic reductive dechlorination can exceed rates of DNAPL dissolution, resulting in aqueous contaminant concentrations in the presence of DNAPL that are substantially lower than saturation levels and are not toxic to the dechlorinating organisms; (ii) enhancements in dissolution will be transient and a function of physico-chemical and biological conditions adjacent to the DNAPL; (iii) demonstration that mass flux reduction behavior can be directly linked to DNAPL source zone architecture; (iv) development of a series of geostatistical approaches capable of quantifying mass discharge uncertainty and guiding real-time sampling design for uncertainty reduction through hot spot delineation ; and (v) creation of a source zone remediation cost estimation tool.
Download or read book DNAPL Source Control by Reductive Dechlorination with Iron based Degradative Solidification stabilization written by Si Hyun Do and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Iron-based degradative solidification/stabilization (Fe(II)-DS/S) is a treatment method that could be economically applied to smaller DNAPL-contaminated sites and to those sites with impermeable soils. Reductive dechlorination is achieved by compounds that are formed by reaction of ferrous iron with components of Portland cement or with defined chemicals (FeCl3 + Ca(OH)2). These dechlorinating agents can effectively degrade chlorinated hydrocarbons (PCE, TCE, and 1,1,1-TCA) that are dissolved in aqueous solution. This research investigated the application of Fe(II)-DS/S to remove chlorinated hydrocarbons that are present as DNAPLs in source zones and to compared the reactivity of ferrous iron in different mixtures, including the conventional mixture with cement (Fe(II)+C) and an iron-solid mixture (ISM) that was synthesized without the addition of cement. The modified first-order model, which the rate was proportional to the concentration of target in the aqueous phase and it was also nearly constant when DNAPL was present, was developed to describe dechlorination kinetics. The modified second-order model assumed that the rate was proportional to the product of the concentration of target in the aqueous phase and the concentration of reductive capacity of the solid reductant. The modified first-order model was used to describe degradation of target compounds with ISM, and the modified second-order model was used to describe removals for TCE and 1,1,1-TCA with Fe(II)+C. Results of experiments on PCE dechlorination with ISM indicated that the increase of Fe(II) in ISM increased rate constants and decreased the solubility of targets. The half-life was increased with increasing total PCE concentration. The product analysis implied that degradation of PCE with ISM was via a combination of the hydrogenolysis and [beta]-elimination pathways. A comparison of the types of targets and reductants indicated that Fe(II)+C had better reactivity for chlorinated ethenes (PCE and TCE) than ISM. However, ISM could dechlorinate a chlorinated ethane (1,1,1-TCA) as rapidly as Fe(II)+10%C. The ratio of [RC]°/[Fe(II)]° implied that Fe(II) in Fe(II)+C was more involved in reducing chlorinated ethenes than was Fe(II) in ISM. Dechlorination of a DNAPL mixture followed the same order of reactivity as with individual DNAPLs with both reductants.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2007 with total page 924 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chlorinated Solvent Source Zone Remediation written by Bernard H. Kueper and published by Springer Science & Business. This book was released on 2014-04-22 with total page 759 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this book is to help engineers and scientists better understand dense nonaqueous phase liquid (DNAPL) contamination of groundwater and the methods and technology used for characterization and remediation. Remediation of DNAPL source zones is very difficult and controversial and must be based on state-of-the-art knowledge of the behavior (transport and fate) of nonaqueous phase liquids in the subsurface and site specific geology, chemistry and hydrology. This volume is focused on the characterization and remediation of nonaqueous phase chlorinated solvents and it is hoped that mid-level engineers and scientists will find this book helpful in understanding the current state-of-practice of DNAPL source zone management and remediation.
Download or read book Partial Mass Recovery from DNAPL Source Zones Contaminant Mass Flux Reductions and Reductive Dechlorination of Residual DNAPL written by Eric John Suchomel and published by . This book was released on 2006 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of this research was to further the understanding of the consequences of partial mass recovery from DNAPL source zones. Particular attention was paid to impact of surfactant-based remediation strategies on post-treatment effluent contaminant concentrations and mass flux as well as the applicability of microbial reductive dechlorination as an efficient polishing mechanism for residual DNAPL present in source zones following aggressive physicochemical treatment. Two dimensional (2-D) experimental results indicated that, for some DNAPL compounds (e.g., TCE), recovery by surfactant-enhanced solubilization using the surfactant Tween 80 is comparable to that observed with low interfacial tension (IFT) solutions designed to mobilize the DNAPL. Hence, Tween 80 (or similar surfactants) should be considered for remediation of TCE source zones, particularly if combined with bioremediation of residual contamination.
Download or read book Modelling of Dissolution and Bioremediation of Chlorinated Ethene DNAPL Source Zones written by Amalia Kokkinaki and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Permanganate Flushing of DNAPL Source Zones Experimental and Numerical Investigation written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laboratory Investigation of Dense Non aqueous Phase Liquid DNAPL Partial Source Zone Remediation Using Cosolvents written by Andrew Joseph Kaye and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: There are hundreds of thousands of commercial, military, and industrial sites across the country where chemical wastes cause contamination to groundwater. Some of the more challenging sites to clean up contain contaminants as dense non-aqueous phase liquids (DNAPLs). There is currently no consensus in the academic, technical and regulatory communities on the ecological or environmental impacts of DNAPL source zone treatment. While many in-situ technologies have shown the ability to remove a significant portion of the contaminant mass, none are able to remove all of it from the source zone. This study investigates the benefits of partial source zone removal using cosolvent flushing. The benefits were assessed by characterizing the relationship between reductions in DNAPL mass and the corresponding reduction in contaminant mass discharge in several laboratory scale experiments. Also, the effects of fluid override and underride associated with cosolvent flushing on the mass reduction (MR) vs. flux reduction (FR) relationship were investigated. The results indicate a model with beta> 1 may be a good approximation of the MR vs. FR relationship using enhanced dissolution by the cosolvents in systems with similar degrees DNAPL and media heterogeneity. Also, the override and underride associated with cosolvents did not significantly affect their remediation.
Download or read book International Seminar On Nuclear War And Planetary Emergencies 46th Session The Role Of Science In The Third Millennium written by Richard C Ragaini and published by World Scientific. This book was released on 2014-07-07 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the 46th Session of the International Seminars on Nuclear War and Planetary Emergencies held in Erice, Sicily. This Seminar has again gathered, in 2013, over 100 scientists from 43 countries in an interdisciplinary effort that has been going on for the last 32 years, to examine and analyze planetary problems which had been followed up, all year long, by the World Federation of Scientists' Permanent Monitoring Panels.
Download or read book Mathematical Modelling of DNAPL Source Zone Remediation written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mathematical modelling was utilized to evaluate trichloroethylene (TCE) and tetrachloroethylene (PCE) dense non-aqueous phase liquid (DNAPL) source zone remediation in the subsurface environment. Semi-analytical solutions were derived, tested, and employed to evaluate the benefits of source zone concentration reduction and solute degradation mechanisms on the evolution of plumes in porous media and fractured rock domains. Simulations of treatment in complex DNAPL source zones using different remedial technologies were completed with a numerical model that was developed, tested, calibrated, and applied to nine idealized heterogeneous porous media sites. Analytical modelling revealed that, in domains dominated by matrix diffusion, aggressive and moderate source zone concentration reduction may have similar effects on the leading edge of the plume. The tailing (near source) edge of the plume may be more responsive to aggressive concentration reduction, particularly when diffusion processes are negligible. Both the near-field (near-source) and far-field plume responses were strongly influenced by the matrix decay half-life for both transient and steady-state conditions. The degradative capacity of the matrix largely dictated plume extent and life-span for the fractured bedrock site considered here. Numerical simulations of in situ source zone treatment with chemical oxidation (ISCO), enhanced bioremediation (ISEB), and surfactants (SEAR) were compared and contrasted. Treatment efficacy was site specific, with benefits observed at some sites, and detrimental impacts observed at others. Each technology demonstrated some degree of performance enhancement relative to dissolution only (no treatment). The maximum DNAPL mass depletion enhancement factors for ISCO, ISEB and SEAR, were 1.44, 2.91, and 2.70 after 10 years, respectively. Similarly, the maximum boundary mass flux enhancement factors for ISCO, ISEB and SEAR were 9.78, 3.32, and 3.97, respectively. While notable enha.
Download or read book Groundwater and Soil Cleanup written by National Research Council and published by National Academies Press. This book was released on 1999-11-21 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a comprehensive, up-to-date review of technologies for cleaning up contaminants in groundwater and soil. It provides a special focus on three classes of contaminants that have proven very difficult to treat once released to the subsurface: metals, radionuclides, and dense nonaqueous-phase liquids such as chlorinated solvents. Groundwater and Soil Cleanup was commissioned by the Department of Energy (DOE) as part of its program to clean up contamination in the nuclear weapons production complex. In addition to a review of remediation technologies, the book describes new trends in regulation of contaminated sites and assesses DOE's program for developing new subsurface cleanup technologies.
Download or read book Comprehensive Biotechnology written by and published by Elsevier. This book was released on 2019-07-17 with total page 4876 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive Biotechnology, Third Edition, Six Volume Set unifies, in a single source, a huge amount of information in this growing field. The book covers scientific fundamentals, along with engineering considerations and applications in industry, agriculture, medicine, the environment and socio-economics, including the related government regulatory overviews. This new edition builds on the solid basis provided by previous editions, incorporating all recent advances in the field since the second edition was published in 2011. Offers researchers a one-stop shop for information on the subject of biotechnology Provides in-depth treatment of relevant topics from recognized authorities, including the contributions of a Nobel laureate Presents the perspective of researchers in different fields, such as biochemistry, agriculture, engineering, biomedicine and environmental science
Download or read book Natural Attenuation for Groundwater Remediation written by Commission on Geosciences, Environment, and Resources and published by National Academies Press. This book was released on 2000-08-31 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past decade, officials responsible for clean-up of contaminated groundwater have increasingly turned to natural attenuation-essentially allowing naturally occurring processes to reduce the toxic potential of contaminants-versus engineered solutions. This saves both money and headaches. To the people in surrounding communities, though, it can appear that clean-up officials are simply walking away from contaminated sites. When is natural attenuation the appropriate approach to a clean-up? This book presents the consensus of a diverse committee, informed by the views of researchers, regulators, and community activists. The committee reviews the likely effectiveness of natural attenuation with different classes of contaminants-and describes how to evaluate the "footprints" of natural attenuation at a site to determine whether natural processes will provide adequate clean-up. Included are recommendations for regulatory change. The committee emphasizes the importance of the public's belief and attitudes toward remediation and provides guidance on involving community stakeholders throughout the clean-up process. The book explores how contamination occurs, explaining concepts and terms, and includes case studies from the Hanford nuclear site, military bases, as well as other sites. It provides historical background and important data on clean-up processes and goes on to offer critical reviews of 14 published protocols for evaluating natural attenuation.
Download or read book In Situ Remediation of Chlorinated Solvent Plumes written by Hans F. Stroo and published by Springer Science & Business Media. This book was released on 2010-09-10 with total page 807 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the late 1970s and early 1980s, our nation began to grapple with the legacy of past disposal practices for toxic chemicals. With the passage in 1980 of the Comprehensive Envir- mental Response, Compensation, and Liability Act (CERCLA), commonly known as Sup- fund, it became the law of the land to remediate these sites. The U. S. Department of Defense (DoD), the nation’s largest industrial organization, also recognized that it too had a legacy of contaminated sites. Historic operations at Army, Navy, Air Force, and Marine Corps facilities, ranges, manufacturing sites, shipyards, and depots had resulted in widespread contamination of soil, groundwater, and sediment. While Superfund began in 1980 to focus on remediation of heavily contaminated sites largely abandoned or neglected by the private sector, the DoD had already initiated its Installation Restoration Program in the mid-1970s. In 1984, the DoD began the Defense Environmental Restoration Program (DERP) for contaminated site assessment and remediation. Two years later, the U. S. Congress codified the DERP and directed the Secretary of Defense to carry out a concurrent program of research, development, and demonstration of innovative remediation technologies. As chronicled in the 1994 National Research Council report, “Ranking Hazardous-Waste Sites for Remedial Action,” our early estimates on the cost and suitability of existing techn- ogies for cleaning up contaminated sites were wildly optimistic. Original estimates, in 1980, projected an average Superfund cleanup cost of a mere $3.
Download or read book Contaminants in the Subsurface written by National Research Council and published by National Academies Press. This book was released on 2005-04-23 with total page 371 pages. Available in PDF, EPUB and Kindle. Book excerpt: At hundreds of thousands of commercial, industrial, and military sites across the country, subsurface materials including groundwater are contaminated with chemical waste. The last decade has seen growing interest in using aggressive source remediation technologies to remove contaminants from the subsurface, but there is limited understanding of (1) the effectiveness of these technologies and (2) the overall effect of mass removal on groundwater quality. This report reviews the suite of technologies available for source remediation and their ability to reach a variety of cleanup goals, from meeting regulatory standards for groundwater to reducing costs. The report proposes elements of a protocol for accomplishing source remediation that should enable project managers to decide whether and how to pursue source remediation at their sites.
