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 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 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 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 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 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.

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 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 Alternatives for Managing the Nation s Complex Contaminated Groundwater Sites written by National Research Council and published by National Academies Press. This book was released on 2013-02-27 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: Across the United States, thousands of hazardous waste sites are contaminated with chemicals that prevent the underlying groundwater from meeting drinking water standards. These include Superfund sites and other facilities that handle and dispose of hazardous waste, active and inactive dry cleaners, and leaking underground storage tanks; many are at federal facilities such as military installations. While many sites have been closed over the past 30 years through cleanup programs run by the U.S. Department of Defense, the U.S. EPA, and other state and federal agencies, the remaining caseload is much more difficult to address because the nature of the contamination and subsurface conditions make it difficult to achieve drinking water standards in the affected groundwater. Alternatives for Managing the Nation's Complex Contaminated Groundwater Sites estimates that at least 126,000 sites across the U.S. still have contaminated groundwater, and their closure is expected to cost at least $110 billion to $127 billion. About 10 percent of these sites are considered "complex," meaning restoration is unlikely to be achieved in the next 50 to 100 years due to technological limitations. At sites where contaminant concentrations have plateaued at levels above cleanup goals despite active efforts, the report recommends evaluating whether the sites should transition to long-term management, where risks would be monitored and harmful exposures prevented, but at reduced costs.

Download or read book Methods and Techniques for Cleaning up Contaminated Sites written by Michael D. Annable and published by Springer Science & Business Media. This book was released on 2008-01-29 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication comprises the presentations made at the NATO Advanced Research Workshop held in Sinaia, Romania 9 – 11 October, 2006. The contributions represent a unique cross section of issues and challenges related to contaminated site management. These range from low cost solutions to petroleum contaminated sites to advances in biological treatment methods. The publication is meant to foster links between groups facing challenges cleaning up contaminated sites.

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 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 Bioaugmentation for Groundwater Remediation written by Hans F. Stroo and published by Springer Science & Business Media. This book was released on 2012-10-02 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: ​This volume provides a review of the past 10 to 15 years of intensive research, development and demonstrations that have been on the forefront of developing bioaugmentation into a viable remedial technology. This volume provides both a primer on the basic microbial processes involved in bioaugmentation, as well as a thorough summary of the methodology for implementing the technology. This reference volume will serve as a valuable resource for environmental remediation professionals who seek to understand, evaluate, and implement bioaugmentation.

Download or read book Applications of Environmental Aquatic Chemistry written by Eugene R. Weiner and published by CRC Press. This book was released on 2012-12-07 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: Professionals and students who come from disciplines other than chemistry need a concise yet reliable guide that explains key concepts in environmental chemistry, from the fundamental science to the necessary calculations for applying them. Updated and reorganized, Applications of Environmental Aquatic Chemistry: A Practical Guide, Third Edition pr

Download or read book Dense Chlorinated Solvents and Other DNAPLs in Groundwater written by James F. Pankow and published by . This book was released on 1996 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Characterization Modeling Monitoring and Remediation of Fractured Rock written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2021-01-29 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fractured rock is the host or foundation for innumerable engineered structures related to energy, water, waste, and transportation. Characterizing, modeling, and monitoring fractured rock sites is critical to the functioning of those infrastructure, as well as to optimizing resource recovery and contaminant management. Characterization, Modeling, Monitoring, and Remediation of Fractured Rock examines the state of practice and state of art in the characterization of fractured rock and the chemical and biological processes related to subsurface contaminant fate and transport. This report examines new developments, knowledge, and approaches to engineering at fractured rock sites since the publication of the 1996 National Research Council report Rock Fractures and Fluid Flow: Contemporary Understanding and Fluid Flow. Fundamental understanding of the physical nature of fractured rock has changed little since 1996, but many new characterization tools have been developed, and there is now greater appreciation for the importance of chemical and biological processes that can occur in the fractured rock environment. The findings of Characterization, Modeling, Monitoring, and Remediation of Fractured Rock can be applied to all types of engineered infrastructure, but especially to engineered repositories for buried or stored waste and to fractured rock sites that have been contaminated as a result of past disposal or other practices. The recommendations of this report are intended to help the practitioner, researcher, and decision maker take a more interdisciplinary approach to engineering in the fractured rock environment. This report describes how existing tools-some only recently developed-can be used to increase the accuracy and reliability of engineering design and management given the interacting forces of nature. With an interdisciplinary approach, it is possible to conceptualize and model the fractured rock environment with acceptable levels of uncertainty and reliability, and to design systems that maximize remediation and long-term performance. Better scientific understanding could inform regulations, policies, and implementation guidelines related to infrastructure development and operations. The recommendations for research and applications to enhance practice of this book make it a valuable resource for students and practitioners in this field.