Download or read book Development and Comparison of a Dechlorinating Mixed Culture and Effects of Triclocarban on Reductive Dechlorination of Trichloroethene written by Katherine G. Muto and published by . This book was released on 2010 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Novel Insights into Algal Biology and Biotechnology written by Yuval Kaye and published by Frontiers Media SA. This book was released on 2019-05-23 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Substrates and Substrate Interactions in Anaerobic Dechlorinating Cultures written by Kai Wei and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of a Trichloroethene dechlorinating Mixed Culture written by Minho Lee and published by . This book was released on 2001 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling Kinetics and Inhibition of Chloroethene Reductive Dechlorination in Mixed Culture written by Qi Meng and published by . This book was released on 2014 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chlorinated ethenes such as tetrachloroethene (PCE) and trichloloethene (TCE) are among the most prevalent contaminants in soil, sediments and groundwaters. Currently, Insitu bioremediation via anaerobic reductive dechlorination has become a widely used technology for groundwater contaminated with chlorinated ethenes. To better understand the reductive dechlorination remediation process and the inter-relationships among the complex microbial communities that comprise it, a comprehensive biokinetic model was recently developed at Cornell University by Gretchen Heavner, a modification of an earlier Cornell model developed by Donna Fennell. The Heavner model uses specific biomasses based on quantitative PCR-based population data, and under some conditions can accurately predict kinetics of dechlorination, fermentation of electron donors, and competition for electron donors between dechlorinators and methanogens, and generation of methane. However, the platform used to run the model - STELLA® (High Performance Systems) - is cumbersome for simulation of long time-spans, limiting the model's utility. Furthermore, the model uses an empirical, "mRNA-tuning" technique to improve data fits at high PCE-loadings, which makes the model descriptive, rather than predictive, in such cases. Additionally, electron donor fermentation is not predicted well at high electron-donor feeding rates. The overall purpose of this thesis research was to address some of the limitations of the Heavner model. The STELLA® model was successfully converted to run in MATLAB® using Runge-Kutta 4th-order integration. The model fits at high-PCE and high electron-donor loadings were improved by utilizing the inhibitory effects of high PCE on dechlorination and methanogenesis, and by postulating additional pathways of butyrate's fermentation and acetate's hydrogenation to storage products. Model simulations indicate that by adding 2nd-order Haldane inhibition instead of mRNA tuning, the model revised in this thesis research predicts the dechlorination, methanogenesis and donor fermentation well over a broad range of PCE feeding rates. Moreover, when simulating donor fermentation at high-PCE-loadings, butyrate's fermentations and acetate's hydrogenation to storage products must be considered to obtain a mass balance between butyrate consumption and product formation.
Download or read book The Activity and Growth of a Chlorophenol Reductively Dechlorinating Soil Culture in the Presence of Exogenous Hydrogen written by Joseph Bryce Lotrario and published by . This book was released on 2000 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: The addition of exogenously supplied hydrogen stimulates PCP reductive dechlorination and increases bacterial growth. While research focuses mainly on pure cultures, few exist capable of aryl reductive dechlorination, and few markers exist to identify reductively dechlorinating bacteria within mixed cultures. Furthermore, most active bioremediation projects stimulate mixed cultures of native biota. This work describes a method to estimate reductively dechlorinating bacterial growth within a mixed soil culture under controlled environmental conditions. The experiments discussed in this paper were performed in a fed-batch reactor. The reactor was operated in a way to maintain environmental conditions such as pH, E[subscript H], headspace concentration, and temperature constant while substrate is allowed to degrade without the corruption of additional changes. Substrate utilization and cell growth were examined under an array of environmental conditions. This dissertation examined the correlation between hydrogen concentration and the growth rate of reductively dechlorinating bacteria. Under low hydrogen partial pressures, between 9.4 x 10−5 and 2.9 x 10−4 atm, the growth rate of reductively dechlorinating bacteria increased as predicted by dual Monod kinetics with respect to hydrogen and chlorophenol concentration; however, studies showed that the relationship was more complex. At higher concentrations of hydrogen, the observed growth rate of reductively dechlorinating bacteria declined. A dual Monod kinetics model with hydrogen substrate inhibition approximates experimental data. Reductive dechlorination of 2,3,4,5-tetrachlorophenol and 3,4,5-trichlorophenol were also studied. Pentachlorophenol reductive dechlorination primarily produces 3,4,5-trichlorophenol via 2,3,4,5-tetrachlorophenol. The reductive dechlorination of 2,3,4,5-tetrachlorophenol parallels that of pentachlorophenol, and the estimated growth rates based on pentachlorophenol and 2,3,4,5-tetrachlorophenol are very similar. Reductive dechlorination of 3,4,5-trichlorophenol was catalyzed by the PCP reductively dechlorinating bacterial culture after a lag period. 3,4,5-Trichlorophenol was not maintained for extended periods, and multiple additions of 3,4,5-trichlorophenol did not result in measurable growth.
Download or read book Investigation of Community Dynamics and Dechlorination Processes in Chlorinated Ethane degrading Microbial Cultures written by Ariel Grostern and published by . This book was released on 2009 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this research was to investigate the microorganisms, genetics and biochemistry of anaerobic dechlorination of chlorinated ethanes, which are common groundwater contaminants. Specifically, this project used mixed microbial cultures to study the dechlorination of 1,2-dichloroethane (1,2-DCA), 1,1,2-trichloroethane (1,1,2-TCA) and 1,1,1-trichloroethane (1,1,1-TCA).A mixed microbial culture enriched from a contaminated multilayered aquifer in West Louisiana dechlorinated 1,2-DCA, 1,1,2-TCA, tetrachloroethene, trichloroethene, cis-dichloroethene and vinyl chloride (VC) to non-toxic ethene when amended with ethanol as the electron donor. 16S rRNA gene sequence analysis revealed the presence of the putative dechlorinating organisms Dehalobacter and Dehalococcoides spp. Denaturing gradient gel electrophoresis analysis and quantitative PCR (qPCR) with species-specific primers demonstrated that both organisms grew during the dichloroelimination of 1,2-DCA to ethene. Conversely, during the dichloroelimination of 1,1,2-TCA to VC only Dehalobacter grew, while during the reductive dechlorination of VC to ethene only Dehalococcoides grew. Further enrichment with 1,2-DCA, H2 and acetate yielded a co-culture of Dehalobacter and Acetobacterium spp. that did not dechlorinate other chlorinated ethanes or ethenes. Dehalobacter grew in the presence but not in the absence of 1,2-DCA, while Acetobacterium growth was not affected by 1,2-DCA. A novel putative Dehalobacter -associated 1,2-DCA reductive dehalogenase gene was identified and was shown to be transcribed only in the presence of 1,2-DCA.An enrichment microbial culture derived from a 1,1,1-TCA-contaminated site in the northeastern United States was also studied. This culture, referred to as MS, reductively dechlorinated 1,1,1-TCA to 1,1-dichloroethane (1,1-DCA) and then to monochloroethane (CA) when amended with methanol, ethanol, acetate and lactate. 16S rRNA gene sequence analysis revealed the presence of the putative dechlorinating organism Dehalobacter sp., whose growth during 1,1,1-TCA and 1,1-DCA dechlorination was confirmed by qPCR. In the presence of chlorinated ethenes, dechlorination 1,1,1-TCA by the culture MS was slowed, while dechlorination of 1,1-DCA was completely inhibited. Experiments with cell-free extracts and whole cell suspensions of culture MS suggested that chlorinated ethenes have direct inhibitory effects on 1,1,1-TCA reductive dehalogenase(s), while the inhibition of 1,1-DCA dechlorination may be due to effects on non-dehalogenase components of Dehalobacter sp. cells. Additionally, two novel reductive dehalogenase genes associated with 1,1,1-TCA reductive dechlorination were identified.
Download or read book Transformation of Carbon Tetrachloride and Chloroform by Trichloroethene Respiring Anaerobic Mixed Cultures and Supernatant written by Kyle E. Vickstrom and published by . This book was released on 2016 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon tetrachloride (CT) and chloroform (CF) were transformed in batch reactor experiments conducted with anaerobic dechlorinating cultures and supernatant (ADC+S) harvested from continuous flow reactors. The Evanite (EV-5L) and Victoria/Stanford (VS-5L) cultures capable of respiring trichloroethene (TCE), 1,2-cis-dichloroethene (cDCE), and vinyl chloride (VC) to ethene (ETH) were grown in continuous flow reactors receiving an influent feed of saturated TCE (10 mM; 60 mEq) and formate (45 mM; 90 mEq) but no CT or CF. In all experiments, cells and supernatant were harvested from the chemostats and inoculated into batch reactors. Transformation of various concentrations of CT (0.86, 2.6, or 8.6 [micro]M), CF (2.1 or 21.1 [micro]M), dichloromethane (DCM; 23.1 [micro]M), and TCE (50 [micro]M) was examined. CT transformation was complete and exhibited pseudo-first order kinetics with CF as the primary measured transformation product in all treatments. Lesser amounts of DCM and carbon disulfide (CS2) were measured leading to an overall mass balance of 20-40% of the original mass as CT accounted for. An analytical first order solution was developed to model CT degradation and product formation under multiple conditions. Cells poisoned with 50 mM sodium azide (NaN3) catalyzed rapid and complete CT transformation suggesting a greater importance of redox active cofactors than live cells in the abiotic and cometabolic transformation. DCM and CS2 however were not produced in the poisoned treatments. TCE and CT simultaneous transformation occurred with an approximately two-fold increase in the CT degradation rate while maintaining complete TCE respiration to ETH. During the initial round of TCE respiration, the rate limiting step was VC to ETH, which was impacted by the presence of CT and CF. A subsequent addition of 50 [micro]M TCE showed a substantial decline in the rates of reductive dechlorination owing to the inhibitory effects of long term exposure to CF. The results clearly demonstrate that transformation can be promoted by anaerobic dechlorinating cultures and supernatant not previously acclimated to CT and CF. However, abiotic reactions account for much of the observed transformation. The role of CF inhibition on H2 utilization by the culture was also explored. Sodium formate was provided as a rapid release substrate, providing H2 as an electron donor. H2 partial pressures were tracked throughout the course of the kinetic experiments. The rapid transformation of CT to CF made it not possible to determine if CT inhibited H2 use by the anaerobic dechlorinating cultures. However, the rapid buildup and subsequent slow transformation of CF was found to reversibly inhibit H2 consumption for homoacetogenesis. It was found that an aqueous CF concentration above 0.4 [micro]M or 0.6 [micro]M inhibited H2 consumption by the EV-5L and VS-5L cultures, respectively. This result differed for the VS-5L culture when metabolizing TCE in the presence of CT and CF. The VS-5L culture consumed H2 at CF concentrations as high as 1.3 [micro]M. The culture may have been partially inhibited at CF concentrations greater than 0.6 [micro]M, which is shown by slower consumption of H2 than controls that did not contain CF. The results demonstrate that CF reversibly inhibits the consumption of H2 by the anaerobic dechlorinating cultures, and that more research is required to determine if it is through a chemical inhibition or toxicity.
Download or read book Measuring in Situ Reductive Dechlorination Rates in Trichloroethene contaminated Groundwater written by Kimberly J. Hageman and published by . This book was released on 2003 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trichloroethene (TCE) is the most frequently detected organic contaminant in groundwater, is classified as a probable human carcinogen, and exhibits toxicological effects on the human endocrine, immune, developmental, and reproductive systems. While significant research efforts have been devoted to the development of strategies for remediating TCE-contaminated groundwater, their advancement is currently hindered by limitations in current methodologies for measuring in situ reductive dechlorination rates, especially for sorbing solutes. This dissertation describes the development, evaluation, and demonstration of a method for measuring in situ reductive dechlorination rates that utilizes single-well, "push-pull" test technology. Initial field tests indicated that trichlorofluoroethene (TCFE) could be used as a surrogate for TCE in push-pull tests since (a) TCE and TCFE were transported similarly and (b) TCFE underwent reductive dechlorination by a pathway analogous to that of TCE while retaining the fluorine label. Because TCFE and TCE experienced sorption at the selected field site, a novel data analysis technique called "forced mass balance" (FMB) was developed to obtain in situ transformation rates of sorbing solutes from push-pull test data. The FMB technique was evaluated by quantifying errors in rates derived by applying FMB to push-pull test data generated by a numerical model. Results from simulated tests indicated that an example in situ rate for the reductive dechlorination of TCFE, which was obtained by applying FMB to field data, was underestimated relative to the true in situ rate by 10%. The utility of the rate-determination method presented in this dissertation was demonstrated by using it to evaluate the effectiveness of a chemical amendment, namely fumarate, at enhancing in situ reductive dechlorination rates in TCE-contaminated groundwater. Reductive dechlorination rates increased following three consecutive additions of fumarate in all five of the tested wells. The development of the rate-determination method described in this dissertation advances the state of bioremediation technology because methods for measuring in situ transformation rates are needed to both assess the potential for natural attenuation and to quantify the effects of bioremediation techniques in the field.
Download or read book Creating Favorable Aquifer Conditions for Reductive Dechlorination of a Mixed Trichloroethene and 1 1 1 trichloroethane Plume written by Rachel B. Leary and published by . This book was released on 2004 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synergistic Reductive Dechlorination of 1 1 1 trichloroethane and Trichloroethene and Aerobic Degradation of 1 4 dioxane written by Yihao Luo and published by . This book was released on 2018 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Widespread use of chlorinated solvents for commercial and industrial purposes makes co-occurring contamination by 1,1,1-trichloroethane (TCA), trichloroethene (TCE), and 1,4-dioxane (1,4-D) a serious problem for groundwater. TCE and TCA often are treated by reductive dechlorination, while 1,4-D resists reductive treatment. Aerobic bacteria are able to oxidize 1,4-D, but the biological oxidation of 1,4-D could be inhibited by TCA, TCE, and their reductive transformation products. To overcome the challenges from co-occurring contamination, I propose a two-stage synergistic system. First, anaerobic reduction of the chlorinated hydrocarbons takes place in a H2-based hollow-fiber "X-film" (biofilm or catalyst-coated film) reactor (MXfR), where "X-film" can be a "bio-film0" (MBfR) or an abiotic "palladium-film" (MPfR). Then, aerobic removal of 1,4-D and other organic compounds takes place in an O2-based MBfR. For the reductive part, I tested reductive bio-dechlorination of TCA and TCE simultaneously in an MBfR. I found that the community of anaerobic bacteria can rapidly reduce TCE to cis-dichloroethene (cis-DCE), but further reductions of cis-DCE to vinyl chloride (VC) and VC to ethene were inhibited by TCA. Also, it took months to grow a strong biofilm that could reduce TCA and TCE. Another problem with reductive dechlorination in the MBfR is that mono-chloroethane (MCA) was not reduced to ethane. In contrast, a film of palladium nano-particles (PdNPs), i.e., an MPfR, could the simultaneous reductions of TCA and TCE to mainly ethane, with only small amounts of intermediates: 1,1-dichloroethane (DCA) (~3% of total influent TCA and TCE) and MCA (~1%) in continuous operation. For aerobic oxidation, I enriched an ethanotrophic culture that could oxidize 1,4-D with ethane as the primary electron donor. An O2-based MBfR, inoculated with the enriched ethanotrophic culture, achieved over 99% 1,4-D removal with ethane as the primary electron donor in continuous operation. Finally, I evaluated two-stage treatment with a H2-based MPfR followed by an O2-MBfR. The two-stage system gave complete removal of TCA, TCE, and 1,4-D in continuous operation.
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 Silver Nanoparticles in the Environment written by Jingfu Liu and published by Springer. This book was released on 2015-04-02 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive book covers the environmental issues concerning silver nanoparticles (AgNPs). Following an introduction to the history, properties and applications, the environmental concerns of AgNPs is discussed. In the second chapter, the separation, characterization and quantification of AgNPs in environment samples are described in detail. In the remaining parts of the book, the authors focus on the environmental processes and effects of AgNPs, with chapters on the pathway into environment, fate and transport, toxicological effects and mechanisms, as well as the environmental bioeffects and safety-assessment of AgNPs in the environment. This book is designed to describe current understanding of the environmental aspects of AgNPs. It provides a valuable resource to students and researchers in environmental science and technology, nanotechnology, toxicology, materials science and ecology; as well as to professionals involved in the production and consumption of AgNPs in various areas including catalysis, food products, textiles/fabrics, and medical products and devices. Jingfu Liu and Guibin Jiang are professors at State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences.
Download or read book Environmental Isotopes in Biodegradation and Bioremediation written by C. Marjorie Aelion and published by CRC Press. This book was released on 2009-11-04 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: Enhanced analytical capabilities and separation techniques, improved detection limits, and accessibility of instrumentation have led to massive strides in the use of isotopes to assess microbial processes in surface and subsurface sediments. Considering the rapid growth of research and commercial interest in stable isotope and radioisotope applicat
Download or read book Compound specific Stable Isotope Analysis written by Maik A Jochmann and published by Royal Society of Chemistry. This book was released on 2015-11-09 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of Compound-specific Stable Isotope Analysis (CSIA) is increasing in many areas of science and technology for source allocation, authentication, and characterization of transformation reactions. Until now, there have been no textbooks available for students with an analytical chemical background or basic introductory books emphasising the instrumentation and theory. This book is the first to focus solely on stable isotope analysis of individual compounds in sometimes complex mixtures. It acts as both a lecture companion for students and a consultant for advanced scientists in fields including forensic and environmental science. The book starts with a brief history of the field before going on to explain stable isotopes from scratch. The different ways to express isotope abundances are introduced together with isotope effects and isotopic fractionation. A detailed account of the required technical equipment and general procedures for CSIA is provided. This includes sections on derivatization and the use of microextraction techniques in GC-IRMS. The very important topic of referencing and calibration in CSIA is clearly described. This differs from approaches used in quantitative analysis and is often difficult for the newcomer to comprehend. Examples of successful applications of CSIA in food authenticity, forensics, archaeology, doping control, environmental science, and extraterrestrial materials are included. Applications in isotope data treatment and presentation are also discussed and emphasis is placed on the general conclusions that can be drawn from the uses of CSIA. Further instrumental developments in the field are highlighted and selected experiments are introduced that may act as a basis for a short practical course at graduate level.
Download or read book Microbial Transformation and Degradation of Toxic Organic Chemicals written by Lily Y. Young and published by Wiley-Liss. This book was released on 1995-08-18 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microorganisms offer a more effective and economical means of reducing or eliminating environmental contamination than more traditional treatment methods. This study examines the role of microbes in the degradation of toxic organic chemicals.
