Download or read book Mechanisms Chemistry and Kinetics of Anaerobic Biodegradation of Cis dichloroethylene and Vinyl Chloride 1998 Annual Progress Report written by and published by . This book was released on 1998 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of this study are to: (1) determine the biochemical pathways for reductive dehalogenation of cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC), including identification of the enzymes involved, (2) determine the chemical requirements, especially the type and quantity of electron donors needed by the microorganisms for reductive dehalogenation, and (3) evaluate the kinetics of the process with respect to the concentration of both the electron donors and the electron acceptors (cDCE and VC). Progress has been made under each of the three primary objectives. One manuscript related to the first objective has been published. Manuscripts related to the other two objectives have been submitted for publication. Findings related to the three objectives are summarized.

Download or read book Mechanisms Chemistry and Kinetics of the Anaerobic Biodegradation of Cis dichloroethylene and Vinyl Chloride First Annual Progress Report September 15 1996 September 14 1997 written by and published by . This book was released on 1997 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: This three-year project is to study the anaerobic biological conversion of cis-1,2- dichloroethene (cDCE) and vinyl Chloride (VC) to ethene. The study is being conducted in three separate phases, the first to better understand the mechanisms involved in cDCE and VC biodegradation, the second to evaluate the chemistry of the processes involved, and the third, to study factors affecting reaction kinetics. Major funding is being provided by the US Department of Energy, but the DuPont Chemical Company has also agreed to directly cost-share on the project at a rate of $75,000 per year for the three year period. Tetrachloroethylene (PCE) and trichloroethylene (TCE) are solvents that are among the most widely occurring organic groundwater contaminants. The biological anaerobic reduction-of chlorinated aliphatic hydrocarbons (CAHs) such as PCE and TCE to cDCE and VC in groundwater was reported in the early 1980s. Further reduction of PCE and its intermediates to ethene was reported in 1989. Several pure cultures of anaerobic bacteria have been found to reductively dehalogenate PCE to cDCE Rates of reduction of PCE and TCE to cDCE are high and the need for electron donor addition for the reactions is small. However, the subsequent reduction of cDCE to VC, and then of VC to the harmless end product, ethene, is much slower and only recently has a pure culture been reported that is capable of reducing cDCE to VC or VC to ethene. There are numerous. reports of such conversions in mixed cultures. The reduction of cDCE and VC to ethene is where basic research is most needed and is the subject of this study.

Download or read book Mechanisms Chemistry and Kinetics of Anaerobic Biodegradation of Cis Dichloroethene and Vinyl Chloride written by and published by . This book was released on 2000 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anaerobic biological processes can result in PCE and TCE destruction through conversion to cis-dichloroethene (cDCE) then to vinyl chloride (VC), and finally to ethene. Here, the chlorinated aliphatic hydrocarbons (CAHs) serve as electron acceptors in energy metabolism, requiring electron donors such as hydrogen from an external source. The purpose of this study was to learn more about the biochemistry of cDCE and VC conversion to ethene, to better understand the requirements for electron donors, and to determine factors affecting the rates of CAH degradation and organism growth. The biochemistry of reductive dehalogenation of VC was studied with an anaerobic mixed culture enriched on VC. In other studies on electron donor needs for dehalogenation of cDCE and VC, competition for hydrogen was found to occur between the dehalogenators and other microorganisms such as methanogens and homoacetogens in a benzoate-acclimated dehalogenating methanogenic mixed culture. Factors affecting the relative rates of destruction of the solvents and their intermediate products were evaluated. Studies using a mixed PCE-dehalogenating culture as well as the VC enrichment for biochemical studies suggested that the same species was involved in both cDCE and VC dechlorination, and that cDCE and VC competitively inhibited each other's dechlorination rate.

Download or read book Laboratory Evaluation of Natural Attenuation and Enhanced Biodegradation of Trichloroethene Cis dichloroethene and Vinyl Chloride Under Anaerobic Conditions written by William B. Bratt and published by . This book was released on 2004 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Kinetics of the Gas phase Photochlorination of Dichloroethylene and Vinyl Chloride written by Alan Joseph Cocker and published by . This book was released on 1960 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Exploring the Limits of Aerobic Vinyl Chloride and Cis dichloroethene Biodegradation Under Suboxic Conditions written by Patrick M. Richards and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An improved understanding of VC and cis-DCE biodegradation under low oxygen conditions could increase the efficiency and sustainability of CE remediation and to expand the use of Monitored Natural Attenuation as a remedial alternative. The overall objective of the studies presented here is to better define the role of aerobic VC and cis-DCE degrading bacteria under suboxic conditions, and to provide practical guidance for expanding the role of aerobic CE biodegradation as a site remediation strategy.

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 Toxicological Profile for Chlordane written by and published by . This book was released on 1994 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Toxicological Profile for 1 1 dichloroethene written by and published by . This book was released on 1994 with total page 208 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 Toxicological Profile for Trichloroethylene written by and published by . This book was released on 1997 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Taking an Exposure History written by Arthur L. Frank and published by . This book was released on 2001 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Toxicological Profile for Tetrachloroethylene written by and published by . This book was released on 1997 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Organohalide Respiring Bacteria written by Lorenz Adrian and published by Springer. This book was released on 2016-08-03 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the current state of knowledge concerning bacteria that use halogenated organic compounds as respiratory electron acceptors. The discovery of organohalide-respiring bacteria has expanded the range of electron acceptors used for energy conservation, and serves as a prime example of how scientific discoveries are enabling innovative engineering solutions that have transformed remediation practice. Individual chapters provide in-depth background information on the discovery, isolation, phylogeny, biochemistry, genomic features, and ecology of individual organohalide-respiring genera, including Dehalococcoides, Dehalogenimonas, Dehalobacter, Desulfitobacterium and Sulfurospirillum, as well as organohalide-respiring members of the Deltaproteobacteria. The book introduces readers to the fascinating biology of organohalide-respiring bacteria, offering a valuable resource for students, engineers and practitioners alike.

Download or read book Permeable Barriers for Groundwater Remediation written by Arun R. Gavaskar and published by . This book was released on 1998 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Because of the limitations of conventional pump-and-treat systems in treating groundwater contaminants, permeable barriers are potentially more cost-effective than pump-and-treat systems for treating dissolved chlorinated solvent plumes, which may persist in the saturated zone for several decades. Other contaminants, such as chromium or other soluble heavy metals, can also be treated with this technology. Permeable Barriers for Groundwater Remediation discusses the types of permeable barriers, their design and construction, and how they can be monitored to evaluate compliance. It provides practical guidance on reactive media selection, treatability testing, hydrogeologic and geochemical modeling, and innovative installation techniques for the evaluation and application of this promising new technology. The types of permeable barriers discussed include: trench-type and caisson-based reactive cells; innovative emplacements, such as horizontal trenching and jetting; and continuous reactive barriers versus funnel-and-gate systems.

Download or read book Surface Water Photochemistry written by Paola Calza and published by Royal Society of Chemistry. This book was released on 2015-11-20 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: Borne out of the current widespread interest in the pollution of water bodies, this book explores the latest research concerning the photochemical fate of organic pollutants in surface water. The main objective is to give insight into both the functioning of ecosystems and the behaviour of emerging pollutants in those ecosystems. Particular importance is dedicated to techniques that can be used in the field and in the laboratory for the detection of pollutants and of their transformation intermediates. The inclusion of photochemical processes that have not gained previous coverage will afford the reader novel insights, whilst the focus on modelling and transformation intermediates will ensure the title's relevance to academics, the chemical manufacturing industries and environmental assessment experts alike.