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Author : William J.. Hickey
Publisher :
ISBN 13 :
Total Pages : 16 pages
Book Rating : 4.:/5 (824 download)
Download or read book Enhanced Reductive Dechlorination of Chlorinated Aliphatic Hydrocarbons written by William J.. Hickey and published by . This book was released on 2008 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Eric Rodriguez
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (526 download)
Download or read book A Field Experiment Evaluating Enhanced Reductive Dechlorination of Chlorinated Solvents in Groundwater written by Eric Rodriguez and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jae-Hyuk Lee
Publisher :
ISBN 13 :
Total Pages : 280 pages
Book Rating : 4.:/5 (741 download)
Download or read book Anaerobic Reductive Dechlorination of TCE and TCFE in TCE Contaminated Sediments written by Jae-Hyuk Lee and published by . This book was released on 2006 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research focused on the enhanced reductive dechlorination of trichloroethene (TCE) and its surrogate, trichlorofluoroethene (TCFE), using two bioremediation methods in anaerobic conditions. Two anaerobic bioremediation studies were conducted to investigate the effects of microbial communities in the presence of different electron acceptors and donors during anaerobic reductive dechlorination of TCE and TCFE. The first study was conducted in the groundwater microcosm bottles, filled with groundwater and sediments collected from Richmond site, CA. Parallel reductive dechlorination of TCE and TCFE was evaluated in the presence of fumarate and its product, succinate, while active reduction of high background concentrations of sulfate (2.5 mM) occurred. Because sulfate was assumed as a favorable electron acceptor during reductive dechlorination of chlorinated aliphatic hydrocarbons (CAHs), all microcosms receiving TCE and TCFE with substrates showed enhanced reductive dechlorination activity and even no substrate addition microcosms generated biotransformation products. From the electron mass balance calculations, more than 87.5% of electrons went to sulfate reduction and less than 10% of available electrons involved in dechlorination after sulfate reductions. After amending varying concentrations of sulfate (0 2.5 mM), no inhibition was found between reductive dechlorination of TCE and sulfate reduction. The result indicated that reductive dechlorination could be directly competed with sulfate reduction for available electrons. The second study investigated the effectiveness of in situ push-pull tests to evaluate bioaugmentation in physical aquifer models (PAMs) using dehalogenating strains to reductively dechlorinate TCE to ethene and TCFE to FE in the TCE contaminated sediments. Complete reduction of TCE to ethene occurred in less than 14 days with repeated additions of TCE (13.0 to 46.0 mg/L) and TCFE (15.0 mg/L) was completely transformed to FE in under 24 days. Increased rate and extent of dechlorination in the bioaugmented PAM compared to the nonaugmented control PAM indicated successful transport of the bioaugmented culture through the PAM. Similar transformation rates and time course of TCE and TCFE also indicated that TCFE was a bioprobe for reductive dechlorination of TCE. TCE and TCFE were transformed to cisdichloroethene (c-DCE) and cis-dichlorofluoroethene (c-DCFE) respectively at two of the three sampling ports after 50 days of incubation in the nonaugmented PAM indicating reductive dechlorination activity of indigenous microorganisms. The results showed that it is possible to increase the rate and extent of reductive dechlorination of TCE and TCFE by bioaugmentation and that push-pull tests are effective tools for detecting and quantifying these processes in situ. The third study focused on numerical modeling of the second study. The objectives of this study were (1) to evaluate a simplified method for estimating retardation factors for injected solutes and bioaugmented microorganisms using "pushpull" test injection phase breakthrough curves, (2) to identify whether bioaugmented microorganisms have kept the same transformation capacity of Evanite culture using Michaelis-Menten kinetics by the values provided by Yu et al. (2005) and to verify in situ rates of TCFE reductive dechlorination rates of push-pull tests by numerical modeling, and (3) to investigate a reasonable answer for the nonuniform recovery of ethene and FE during the activity test and the push-pull test. The bioaugmented microorganisms were effectively transported through Hanford sediment. The estimated retardation factor was 1.33. A numerical simulation predicted cell transport in the PAM as far as port 5. This was qualitatively confirmed by cell counts obtained during bioaugmentation but, cells were distributed nonuniformly. The transport test indicated that TCE and TCFE transport was relatively retarded compared to coinjected bromide tracer (retardation factors ranged from 1.33-1.62 for TCE and from 1.44-1.70 for TCFE). The modeling simulation of Michaelis-Menten kinetics for the activity test was well matched for reductive dechlorination rates for TCE and less dechlorinated ethenes using the previous published values of kmax and Ks of chlorinated ethenes by Yu et al. (2005); the model match indicated that the bioaugmented microorganisms kept the same transformation capacity as the original source, Evanite culture (Yu et al., 2005) over 4 months in the PAM. A numerical simulation resulted in the simple first order FE production rate of 1 day' using STOMP code (2002) and the value of FE production rate was in the range of the transformation rates of TCFE during the activity test. The bioaugmented PAM has caused slow loss of injected CAHs during the activity test and the push-pull test.
Author :
Publisher :
ISBN 13 :
Total Pages : 94 pages
Book Rating : 4.:/5 (318 download)
Download or read book In-situ Substrate Addition to Create Reactive Zones for Treatment of Chlorinated Aliphatic Hydrocarbons: Cost and Performance Report written by and published by . This book was released on 2007 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chlorinated solvent contamination of groundwater is a widespread problem at many military and civilian facilities. This class of compounds includes widely used chlorinated aliphatic hydrocarbons (CAH) such as carbon tetrachloride, methylene chloride, trichloroethane, trichloroethene (TCE) and tetrachloroethene. In addition to their roles in many industrial processes, CAHs have been used extensively for cleaning and degreasing. The U.S. Armed Forces are faced with widespread, costly remediation problems related to these compounds. The conventional remedies for CAH contamination in groundwater are groundwater extraction and ex situ treatment, also known as pump and treat, or in situ air sparging. An alternative approach is anaerobic in situ reactive zone (IRZ) technology for the remediation of CAHs and metals. Anaerobic IRZ technology involves the addition of a food grade, soluble carbohydrate substrate, which serves as a supplemental energy source for microbiological processes in the subsurface. The substrate is typically molasses, but other substrates can be used, including high fructose corn syrup, whey, etc. Through subsurface carbohydrate injection, aerobic or mildly anoxic aquifers can be altered to highly anaerobic reactive zones. This creates suitable conditions for the biodegradation of CAHs and/or the precipitation of selected metals in insoluble forms. This technology is more specifically referred to as enhanced reductive dechlorination (ERD) for CAHs or enhanced anaerobic reductive precipitation (EARP) for metals. The primary benefits of ERD technology include its ease of regulatory acceptance, its in situ nature and its relatively low cost. Benefits of ERD technology include its record of successful application at various constituent concentrations, in varied geologies, and under multiple regulatory programs.
Author : Bahng Mi Jung
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (126 download)
Download or read book Reductive Dechlorination of Chlorinated Aliphatic Hydrocarbons by Fe(II) in Degradative Solidification/stabilization written by Bahng Mi Jung and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation examines the applicability of the iron-based degradative solidification/stabilization (DS/S-Fe(II)) to various chlorinated aliphatic hydrocarbons (CAHs) that are common chemicals of concern at contaminated sites. The research focuses on the transformation of 1,1,1-trichloroethane (1,1,1-TCA), 1,1,2,2-tetrachloro-ethane (1,1,2,2-TetCA) and 1,2-dichloroehtane (1,2-DCA) by Fe(II) in cement slurries. It also investigates the degradation of 1,1,1-TCA by a mixture of Fe(II), cement and three iron-bearing phyllosilicates. Transformation of 1,1,1-TCA and 1,1,2,2-TetCA by Fe(II) in 10% cement slurries was characterized using batch reactors. Dechlorination kinetics of 1,1,1-TCA and TCE* (TCE that was produced by transformation of 1,1,2,2-TetCA) was strongly dependent on Fe(II) dose, pH and initial target organic concentration. Degradation of target organics in DS/S-Fe(II) process was generally described by a pseudo-first-order rate law. However, saturation relationships between the rate constants and Fe(II) dose or between the initial degradation rates and target organic concentration were observed. These behaviors were properly described by a modified Langmuir-Hinshelwood kinetic model. This supports the working hypothesis of this research that reductive dechlorination of chlorinated ethanes occurs on the surface of active solids formed in mixtures of Fe(II) and cement. Transformation products for 1,1,1-TCA and 1,1,2,2-TetCA in mixtures of Fe(II) and cement were identified. The major product of the degradation of 1,1,1-TCA was 1,1-DCA, which indicates that the reaction followed a hydrogenolysis pathway. However, a small amount of ethane was also observed. TCE* was rapidly produced by degradation of 1,1,2,2-TetCA and is expected to undergo [beta]-elimination to produce acetylene. Dechlorination of 1,1,1-TCA in suspension of Fe(II), cement and three soil minerals (biotite, vermiculite, montmorillonite) was characterized using batch reactors. A first-order rate model was generally used to describe the dechlorination kinetics of 1,1,1-TCA in this heterogeneous system. The rate constants for 1,1,1-TCA in mixtures of Fe(II), cement and soil minerals were influenced by soil mineral types, Fe(II) dose and the mass ratio of cement to soil mineral. It was demonstrated that structural Fe(II) and surface-bound Fe(II) in the soil minerals affect dechlorination kinetics and the effects vary with mineral types. Furthermore, it suggests that the reductant formed from Fe(II) and cement hydration components is also effective in systems that include soil minerals.
Author : Juan C. Sanchez-Hernandez
Publisher : CRC Press
ISBN 13 : 1351793101
Total Pages : 247 pages
Book Rating : 4.3/5 (517 download)
Download or read book Bioremediation of Agricultural Soils written by Juan C. Sanchez-Hernandez and published by CRC Press. This book was released on 2019-03-14 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: The quality of agricultural soils are always under threat from chemical contaminants, which ultimately affect the productivity and safety of crops. Besides agrochemicals, a new generation of substances invades the soil through irrigation with reclaimed wastewater and pollutants of organic origin such as sewage sludge or cattle manure. Emerging pollutants such as pharmaceuticals, nanomaterials and microplastics are now present in agricultural soils, but the understanding of their impact on soil quality is still limited. With focus on in situ bioremediation, this book provides an exhaustive analysis of the current biological methodologies for recovering polluted agricultural soils as well as monitoring the effectiveness of bioremediation.
Author : Robert E. Hinchee
Publisher :
ISBN 13 :
Total Pages : 360 pages
Book Rating : 4.F/5 ( download)
Download or read book Bioremediation of Chlorinated Solvents written by Robert E. Hinchee and published by . This book was released on 1995 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil and groundwater contamination stemming from the release of various chlorinated compounds into the environment is a significant and difficult site remediation challenge. The articles in this collection discuss the use of aerobic and anaerobic biological degradation to dehalogenate sites contaminated with pesticides and chlorinated solvents such as trichloroethylene, tetrachloroethene, tetrachloromethene, perchloroethylene, carbon tetrachloride, pentachlorophenol, and chlorinated benzene. Bench- and field-scale studies of the biological processes associated with in situ dechlorination of soil and aquifers are described. Discussed are the uses of microcosm studies and numerical simulation of dechlorination to manage system operation. Site characteristics (e.g., hydraulic properties, temperature, nitrogen availability) and their effect on the stability of the methanotrophic community are examined. Methods discussed include the use of air venting, alternative electron donors, biofilm reactors, surfactants, municipal digester sludge, iron enhancement, and sulfate reduction to improve conditions for the microbial consortia that effect dechlorination.
Author : Yi Yang
Publisher :
ISBN 13 :
Total Pages : 117 pages
Book Rating : 4.:/5 (843 download)
Download or read book Exploring Anaerobic Reductive Dechlorination at Low PH Environments written by Yi Yang and published by . This book was released on 2012 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chlorinated aliphatic hydrocarbons (CAHs), such as tetrachloroethene (PCE) and trichloroethene (TCE), are ubiquitously pollutants in aquifer sediments and groundwater due to their heavy usage in industry and inappropriate disposal in the last century. Among about 1300 NPL (National Priorities List) sites, PCE and TCE are the two most frequently detected hazardous contaminants. Engineered bioremediation, including biostimulation and bioaugmentation, is a promising technology to clean those PCE and/or TCE contaminated sites. However, in many contaminated groundwater systems and hazardous waste sites, pH can be lower than 5 to 6. And release of HCl (strong acid) from anaerobic reductive dechlorination may lower the pH of groundwater. Besides, another main source of acidity comes from the fermentation of additive electron donors such as alcohols, organic acids and etc. Decreasing pH has been proved to be detrimental to the microbes that dechlorinated PCE or TCE. We intended to enrich and isolate microorganisms, which can perform anaerobic reductive dechlorination at low pH environments, by establishing microcosms, which will be beneficial to in situ bioremediation. We also screened some existing cultures for dechlorinating activity at low pH and determined the pH tolerance of consortium BDI, which had been successfully, applied for in situ bioremediation. Besides, this study investigated and explored the effects of solids on BDI consortium under low pH conditions. Generally, various dechlorinating pure cultures and consortium BDI show highest dechlorination rates and extent at circumneutral pH. Only Sulfurospirillum multivorans among tested cultures dechlorinated PCE to cDCE at pH 5.5. The screening efforts suggest that microbes capable of dechlorination below pH 5.5 are not common. It was observed that solids play an important role for enhancing microbial activities under low pH conditions. And BDI consortium can recover from up to 8 weeks exposure to low pH conditions, although the VC-to-ethene dechlorination step was affected.
Author :
Publisher :
ISBN 13 :
Total Pages : 457 pages
Book Rating : 4.:/5 (15 download)
Download or read book Principles and Practices of Enhanced Anaerobic Bioremediation of Chlorinated Solvents written by and published by . This book was released on 2004 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Department of Defense (DoD) has identified hundreds of sites where groundwater is contaminated with chlorinated solvents; these represent one of the DoD's largest remediation liabilities. In addition to their use in many industrial processes, chlorinated solvents have historically been used for cleaning and degreasing such diverse products as aircraft engines, automobile parts, electronic components, and clothing in the military and commercial sectors. Chlorinated solvents were often released to the subsurface environment in waste water or in the form of dense non-aqueous phase liquids (DNAPLs). As a result of their physical and chemical properties, DNAPLs are difficult to remediate once they have migrated into groundwater aquifers. Enhanced in situ anaerobic bioremediation can be an effective method of degrading various chlorinated solvents dissolved in groundwater, including chloroethenes, chloroethanes, and chloromethanes. Collectively, these compounds (some of which are degradation products of chlorinated solvents) are referred to as chlorinated aliphatic hydrocarbons (CAHs). Advantages of enhanced anaerobic bioremediation include complete mineralization of the contaminants in situ with little impact on infrastructure and relatively low cost compared to more active engineered remedial systems.
Author : Victor Magar
Publisher :
ISBN 13 :
Total Pages : 408 pages
Book Rating : 4.3/5 (91 download)
Download or read book Anaerobic Degradation of Chlorinated Solvents written by Victor Magar and published by . This book was released on 2001 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: The symposium included 600 presentations in 50 sessions on bioremediation and supporting technologies used for a wide range of contaminants already in, or poised to invade, soil, groundwater, and sediment. Three hundred and fifty-two papers were selected and organized into ten volumes. Volume seven's articles examine the use of enhanced anaerobic biotransformation processes for treatment of chlorinated solvents in soil and groundwater. Electron donors used to stimulate reductive dechlorination processes in lab- and field-scale demonstrations are also presented. Articles average eight pages, and contain abstracts and references. Annotation copyrighted by Book News Inc., Portland, OR.
Author : Celia Maria Alcantar
Publisher :
ISBN 13 :
Total Pages : 206 pages
Book Rating : 4.3/5 (121 download)
Download or read book Preliminary Assessment of Potential for Natural Attenuation of Chlorinated Aliphatic Hydrocarbons in the Subsurface at Site 5, Alademda Point, Alameda, CA written by Celia Maria Alcantar and published by . This book was released on 1997 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Young-Hun Kim
Publisher :
ISBN 13 :
Total Pages : 320 pages
Book Rating : 4.:/5 (435 download)
Download or read book Reductive Dechlorination of Chlorinated Aliphatic and Aromatic Compounds Using Zero Valent Metals written by Young-Hun Kim and published by . This book was released on 1999 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Hans F. Stroo
Publisher : Springer Science & Business Media
ISBN 13 : 1461441153
Total Pages : 421 pages
Book Rating : 4.4/5 (614 download)
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.
Author : Ida Damgaard
Publisher :
ISBN 13 : 9788792654571
Total Pages : pages
Book Rating : 4.6/5 (545 download)
Download or read book Enhanced Reductive Dechlorination in Clay Till Contaminated with Chlorinated Solvents written by Ida Damgaard and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Sukil Son
Publisher :
ISBN 13 :
Total Pages : 294 pages
Book Rating : 4.:/5 (519 download)
Download or read book Reductive Dechlorination of Chlorinated Hydrocarbons Using Fe(II) and Modified Green Rusts in Degradative Solidification/stabilization written by Sukil Son and published by . This book was released on 2002 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Commission on Geosciences, Environment, and Resources
Publisher : National Academies Press
ISBN 13 : 0309069327
Total Pages : 289 pages
Book Rating : 4.3/5 (9 download)
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.
Author : Caroline Burda
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (53 download)
Download or read book Enhancing Reductive Dechlorination of Chlorinated Ethenes and Ethanes in a Natural Treatment System written by Caroline Burda and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
