Download or read book Effect of Chlorinated Ethene Biodegradation on Growth Rates of Methanotrophic Bacteria in Biofilms and Mixed Cultures written by James Eric Anderson and published by . This book was released on 1996 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1997 with total page 826 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effects of Fe III Reduction on Biodegradation of Fuel Oxygenates and Chlorinated Ethenes written by Na Wei and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel oxygenates, methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA), and chlorinated ethenes (TCE, cis-DCE and VC) are two groups of contaminants prevalent in groundwater systems. Fe(III) reducing conditions are dominant in many sedimentary environments. However, the effects of Fe(III) reduction on biotransformation of MTBE/TBA and chlorinated ethenes are not well understood. This research investigated the biodegradation of these contaminants and related microbial ecology under Fe(III)-reducing conditions in both sediment microcosms and enrichment cultures. The primary limitation to understanding anaerobic MTBE biodegradation is the lack of liquid cultures with consistent activity. This study enriched three distinct MTBE-degrading, anaerobic cultures from contaminated aquifer material, and they use anthraquinone-2,6-disulfonate, sulfate and fumarate as the terminal electron acceptor, respectively. Phylogenetic analyses based on 16S rRNA gene suggested novel microorganisms involved in anaerobic MTBE biodegradation. These cultures are the first stable, sediment-free anaerobic MTBE-degrading cultures, which provide model systems for mechanistic studies of anaerobic MTBE biodegradation. Substantial [U-14C]-TBA mineralization occurred under Fe(III)-reducing conditions. The TBA biodegradation activity was correlated with the abundance of one dominant clone, which is closely associated with organisms belonging to the Alphaproteobacteria. The results provide the original evidence of the stimulative effect of Fe(III) reduction on anaerobic TBA mineralization, and give initial insight to the organisms that may catalyze the anaerobic TBA mineralization reactions. The experimental study on the effects of Fe(III) reduction on reductive dechlorination demonstrated that Fe(III) reduction did not inhibit complete dechlorination, which is in contrast to the common opinion that TCE dechlorination will be inhibited wherever there is bioavailable Fe(III). Fe(III) speciation has an impact on daughter product distribution and dechlorination kinetics. Quantitative PCR analysis revealed that Dehalococcoides and Geobacteraceae organisms were enriched concurrently in the dechlorinating Fe(III)-reducing sediments/cultures; Dehalococcoides abundance in the presence of Fe(III) was not significantly different from that in the cultures without Fe(III), meaning Fe(III) reducers would not outcompete and inhibit Dehalococcoides growth. Also, Fe(III) reduction may stimulate growth of G. lovleyi like organisms and contribute to TCE dechlorination to cis-DCE. Enrichment culture study demonstrated that Fe(III) reduction poised the hydrogen concentration at an appropriate steady-state that is within the ideal range for reductive dechlorination when acetate was amended as the sole electron donor. 10X excessive electron donor addition did not facilitate chlorinated ethene dechlorination, but led to considerably high methane production and enrichment of methanogens. The results suggest that adding surplus electron donor will not only cause substrate wastage and unnecessary cost in bioremediation, but also have adverse effects such as enhanced methane release.

Download or read book American Doctoral Dissertations written by and published by . This book was released on 1996 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Methanotrophic Vinyl Chloride Biodegradation written by Yarrow Michael Nelson and published by . This book was released on 1993 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Biodegradation of Chlorinated Ethenes in Mixed Waste Streams written by and published by . This book was released on 2004 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes research conducted from 04/01/01 to 08/31/04 with support from the US Army Research Office DoD-EPSCoR program. The goal of the research was to study the biodegradation of chloroethenes under serial anaerobic/aerobic conditions. In the system used water flowed through a contact chamber containing chloroethenes. Contaminated water was then pumped through a sediment column. From the sediment column the water flowed into an aerated chamber. Chloroethenes concentrations were determined in samples from the contact chamber the sediment column and the aerobic chamber. We tested means for establishing anaerobiosis in the sediment column two sparging gas mixtures addition of lactate as a growth substrate control of conditions in the aerobic chamber and the presence of a hydrocarbon fuel mixture as a co-contaminant. Results indicated that a N2:H2 gas mixture stimulated POE degradation. We also found that the addition of exogenous lactic acid (2 mM) and the presence of petroleum hydrocarbons in reactor feed water resulted in 99.6% removal of PCE and 99.2% reduction in the total molar concentration of chloroethenes. In the last year of the research we established mixed microbial cultures in which vinyl chloride disappearance was concomitant with an increase in chloride concentration and biomass accumulation.

Download or read book Applied and Environmental Microbiology written by and published by . This book was released on 1997 with total page 868 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Immobilised Biocatalysts for Bioremediation of Groundwater and Wastewater written by Rita Hochstrat and published by IWA Publishing. This book was released on 2015-02-15 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: The European project MINOTAURUS explored innovative bio-processes to eliminate emerging and classic organic pollutants. These bio-processes are all based on the concept of immobilization of biocatalysts (microorganisms and enzymes) and encompass bioaugmentation, enzyme technology, rhizoremediation with halophytes, and a bioelectrochemical remediation process. The immobilization-based technologies are applied as engineered ex situ treatment systems as well as natural systems in situ for the bioremediation of groundwater, wastewater and soil. The selection and application of tailored physico-chemical, molecularbiological and ecotoxicological monitoring tools combined with a rational understanding of engineering, enzymology and microbial physiology is a pertinent approach to open the black-box of the selected technologies. Reliable process monitoring constitutes the basis for developing and refining biodegradation kinetics models, which in turn improve the predictability of performances to be achieved with technologies. Immobilised Biocatalysts for Bioremediation of Groundwater and Wastewater delivers insight into the concepts and performance of a series of remediation approaches. A key strength of this book is to deliver results from lab-scale through to piloting at different European reference sites. It further suggests frameworks for structuring and making evidence-based decisions for the most appropriate bioremediation measures.

Download or read book Development of a Method to Elucidate Biodegradation Pathways of Chlorinated One and Two Carbon Compounds Using a Gas permeable membrane supported Methylotrophic Biofilm written by Kelly M. Ryan and published by . This book was released on 1988 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: A gas-permeable-membrane-supported (GPMS) biofilm consisting of methylotrophic bacteria was effective in degrading chlorinated methanes, ethanes, and ethenes. The biofilm was developed on a gas-permeable fabric (Goretex, W.L. Gore & Associates, Elkton, Maryland) that divided a reactor vessel into a liquid compartment and a gas compartment. Goretex is a nylon-backed teflon mesh that allows gas transfer, but is impermeable to water. Methane and oxygen were diffused from a gas compartment, through the membrane, to the methylotrophic biofilm on the liquid side of the membrane. During the biofilm's development, methane served as the sole carbon source and electron donor, and oxygen served as the electron acceptor. Inorganic nutrients were supplied in the bulk aqueous solution. The chlorinated compounds were added to the bulk liquid. Removal of the compounds was monitored and the methylotrophic GPMS biofilm was shown to be effective in degrading dichloromethane, 1,2-dichloroethane; and cis 1,2-dichloroethene. Rates of degradation increased in the order of chlorinated ethene, ethane, and methane. The GPMS system can be operated in either batch or continuous flow mode with similar degradation rates resulting from each process. A model was developed to predict metabolic product concentration as a function of time and retention time in batch or continuous flow reactors. No metabolic products were detected, but it is apparent that the degradation rates of any metabolites of dichloromethane or 1,2-dichloroethane are probably at least ten times greater than that of the original parent compounds.

Download or read book Biodegradation of Chlorinated Methanes Using a Methylotrophic anaerobic Biofilm Reactor written by Stephen J. Celeste and published by . This book was released on 1990 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chlorinated low molecular weight solvents have been discovered in a number of the nation's groundwater supplies. Remediation of these aquifers will require some form of treatment. Presently, the dominant treatment method is air stripping which results in transfer of the solvent from the aqueous phase into the atmosphere. Biodegradation is an attractive alternative because the solvents can be converted into harmless by-products. This study explored the use of a combination of methylotrophic and anaerobic bacteria to biodegrade chlorinated methanes. The objectives were to develop a reactor system capable of sustaining both methylotrophic and anaerobic bacterial populations, and to evaluate the biodegradation of chlorinated methanes in this system. A gas permeable membrane (Goretex) separated the reactor into a liquid compartment and a gas compartment. The methylotrophs were provided methane as an electron donor and oxygen as an electron acceptor. Inorganic nutrients and chlorinated methanes were supplied in the bulk solution. Methane and chloromethanes were the sole sources of carbon supplied to the reactor. The membrane was rotated as a flat plate to ensure complete mixing and to encourage growth of a biofilm of uniform thickness. The methylotrophic bacteria were grown as a biofilm on a gas permeable membrane. The anaerobic bacteria appeared to grow both as a biofilm and in suspension in the bulk solution. The chlorinated methane concentrations were measured in the headspace, gas compartment, and liquid compartment. Oxygen and methane use was also monitored. The reactor was operated in batch mode, and the biofilm was assumed to be in a quasi-steady state condition with respect to growth. The combined methylotrophic/anaerobic biofilm system was effective in biodegrading carbon tetrachloride, chloroform, and dichioromethane. Carbon tetrachloride removal was accompanied by production of chloroform and trace amounts of dichloromethane, which is consistent with an anaerobic dechlorination pathway. Dichloromethane removal was inhibited in the absence of oxygen, which is consistent with a biological oxidation pathway. Chloroform removal under anoxic conditions was accompanied by production of dichloromethane, suggesting an anaerobic dechlorination pathway. Under aerobic conditions, the removal rate of chloroform increased nearly four fold, indicating that chloroform was biologically oxidized as well as anaerobically dechlorinated. Dechlorination of carbon tetrachloride and oxidation of dichioromethane occurred most rapidly, followed by combined dechlorination and oxidation of chloroform.

Download or read book A Comparison of Modeling Approaches in Simulating Chlorinated Ethene Removal in a Constructed Wetland by a Microbial Consortia written by Jason S. Campbell and published by . This book was released on 2002-03 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study is to compare different approaches to modeling the reductive dechlorination of chlorinated ethenes in the anaerobic region of an upward flow constructed wetland by microbial consortia. A controlled simulation experiment that compares three different approaches to modeling the degradation of chlorinated ethenes in wetland environments is conducted and investigates how each of the modeling approaches affect simulation results. Concepts like microbial growth in the form of a biofilm and spatially varying contaminant concentrations bring the validity of the CSTR assumption into question. These concepts are incorporated into the different modeling approaches to evaluate the CSTR assumption. Model simulations show that spatially varying contaminant concentrations have a significant effect on contaminant effluent concentrations. Additionally, the significance of the incorporation of a biofilm concept depends on the time characteristics of both diffusive mass transport and reaction kinetics.

Download or read book Aerobic Degradation of Chlorinated Ethenes by Mycobacterium Strain JS60 in the Presence of Organic Acids written by Christina Blatchford and published by . This book was released on 2005 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study evaluated the potential of the aerobic Mycobacterium strain JS6O to grow on a variety of organic acid substrates, and the possible effects an organic acid would have on the degradation rate of vinyl chloride (VC). A series of batch growth tests were designed to determine the time it took to consume the substrate and the overall increase in biomass. Strain JS6O was found capable of growth on acetate, propionate, and butyrate, but could not grow on formate or lactate. Acetate was chosen for further study because strain JS6O consumed acetate the most rapidly of all the organic acids tested, and acetate is a common product of fermentation reactions in the subsurface. Strain JS6O was confirmed to grow on both ethylene and vinyl chloride as the sole carbon and energy source. Comparatively, strain JS6O's rate of growth on VC is much slower than that of ethylene. With acetate as an augmenting growth substrate, ethylene and VC utilization rates increased by 30% and 48%, respectively. Since acetate and VC are often found together in contaminated chlorinated ethene plumes, this makes a strong case for natural attenuation of VC by strain JS6O. A series of kinetic tests were implemented to determine the K[subscript s] and k[subscript max] of strain JS6O for ethylene, VC, and c-DCE. The K[subscript s] and k[subscript max] for ethylene determined through NLSR methods was similar to the values published in Coleman et al. (2002), supporting the maintenance of a pure culture throughout the experimental work. When strain JS6O was exposed to the isomers of DCE (trans-1,2-dichloroethylene (t-DCE), cis-1,2-dichloroethylene (c-DCE), and 1,1-dichloroethylene (1,1-DCE)) the cells were unable to grow on these compounds. However, when growing on acetate, strain JS6O cometabolized c-DCE and t-DCE, but not 1,1-DCE, with c-DCE transformed more rapidly than t-DCE. Transformation of c-DCE was also observed with growth on VC and ethylene. The presence of c-DCE was shown to partially inhibit VC degradation, but had no effect on ethylene degradation. The cometabolism results with acetate further indicate that strain JS6O is a good candidate for natural attenuation of multiple chlorinated ethenes in the subsurface.

Download or read book Biological Degradation of Organic Chemical Pollutants in Biofilm Systems written by E. Arvin and published by IWA Publishing (International Water Assoc). This book was released on 1995 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is no description available for this title

Download or read book Biodegradation and Electro assisted Biodegradation of 1 4 dioxane Under Different Electron Accepting Conditions written by Aryan Samadi and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1,4-Dioxane (DX) is an emerging contaminant of concern in water resources. In the past, it was commonly utilized to stabilize chlorinated solvents, and it has now been discovered as a contaminant present in various personal care and food products. DX is also used in many industries including plastics and polymers, adhesiveness and sealants, and pharmaceuticals. Therefore, discharge from industrial processes is the major route of DX release to the water bodies. Once discharged to the environment, DX mostly ends up in groundwaters and is persistent (half-life of 3-5 years) and causes ecological and human health impacts if exposed (a probable carcinogen). This thesis focuses on developing novel, green and effective processes for removal of 1,4-dioxnae from water. The main objective was to fill the knowledge gaps in the literature about (1) DX biodegradation in low dissolved oxygen concentrations, (2) effect of carrier's properties on growth of DX-degrading biofilm, and (3) mechanisms of electrochemical stimulation of DX biodegradation. In order to answer the related research questions to each gap, experiments were designed systematically and performed in lab-scale batch or continuous reactors using pure culture or microbial community as the inoculation source. Experiments conducted under low dissolved oxygen concentrations (between 1-3 mg/L) demonstrated that the biodegradation of DX occurred at a very slow rate (0.21 mgDX/L/day) when external sources of oxygen were not provided. As time passed, the overall diversity and richness of the microbial community decreased, though certain genera, such as Pseudonocardiaceae, Xanthobacteraceae, and Chitinophagaceae, were able to thrive by using DX as a carbon source. These findings suggest that the microbial community has the ability to adapt to different electron-accepting conditions, which could be beneficial for in-situ bioremediation or natural attenuation of DX in water resources. Experiments conducted on delignified porous wood as biofilm carriers demonstrated an improvement in biofilm formation in terms of growth rate and hydrophilicity compared to natural untreated wood as biofilm carriers. This improvement was attributed to the superior physiochemical properties of the treated wood, which exhibited higher porosity, formation of macropores, and an increase in surface roughness and hydrophilicity compared to untreated wood. Moreover, the rate of DX biodegradation increased by 5.33-fold when treated woods were used as carriers compared to untreated woods. These findings shed light on the physiochemical properties of biofilm carriers that contribute to biofilm formation and can be valuable for ongoing research on DX bioremediation. The experiments on electrochemical stimulation of DX biodegradation in a continuous flow bioelectrochemical reactor revealed that two different mechanisms could be responsible for the observed stimulation at low applied voltages between 1.0-1.2 V. One mechanism was attributed to the production of oxygen as a result of the water electrolysis reaction occurring at 1.2 V. This oxygen could then serve as a source of electron acceptor for aerobic microorganisms in the medium. The other mechanism was linked to an increase in microbial population activity due to electrochemical stimulation at 1.0 V. The analysis of changes in microbial composition revealed the enrichment of Alistipes and Lutispora at 1.0 V, which was attributed to their ability to directly transfer electrons with a conductive surface. The results can be helpful to issue the challenge of lack of electron acceptors in DX bioremediation.

Download or read book Biodeterioration and Biodegradation 9 written by Andrew Bousher and published by . This book was released on 1995 with total page 690 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents the proceedings of an International Biodegradation Association conference held in September 1993 in Leeds.

Download or read book Linking Structure and Function to Manage Microbial Communities Carrying Out Chlorinated Ethene Reductive Dechlorination written by Michal Ziv-El and published by . This book was released on 2012 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contamination by chlorinated ethenes is widespread in groundwater aquifers, sediment, and soils worldwide. The overarching objectives of my research were to understand how the bacterial genus Dehalococcoides function optimally to carry out reductive dechlorination of chlorinated ethenes in a mixed microbial community and then apply this knowledge to manage dechlorinating communities in the hydrogen-based membrane biofilm reactor (MBfR). The MBfR is used for the biological reduction of oxidized contaminants in water using hydrogen supplied as the electron donor by diffusion through gas-transfer fibers. First, I characterized a new anaerobic dechlorinating community developed in our laboratory, named DehaloR^2, in terms of chlorinated ethene turnover rates and assessed its microbial community composition. I then carried out an experiment to correlate performance and community structure for trichloroethene (TCE)-fed microbial consortia. Fill-and-draw reactors inoculated with DehaloR^2 demonstrated a direct correlation between microbial community function and structure as the TCE-pulsing rate was increased. An electron-balance analysis predicted the community structure based on measured concentrations of products and constant net yields for each microorganism. The predictions corresponded to trends in the community structure based on pyrosequencing and quantitative PCR up to the highest TCE pulsing rate, where deviations to the trend resulted from stress by the chlorinated ethenes. Next, I optimized a method for simultaneous detection of chlorinated ethenes and ethene at or below the Environmental Protection Agency maximum contaminant levels for groundwater using solid phase microextraction in a gas chromatograph with a flame ionization detector. This method is ideal for monitoring biological reductive dechlorination in groundwater, where ethene is the ultimate end product. The major advantage of this method is that it uses a small sample volume of 1 mL, making it ideally suited for bench-scale feasibility studies, such as the MBfR. Last, I developed a reliable start-up and operation strategy for TCE reduction in the MBfR. Successful operation relied on controlling the pH-increase effects of methanogenesis and homoacetogenesis, along with creating hydrogen limitation during start-up to allow dechlorinators to compete against other microorgansims. Methanogens were additionally minimized during continuous flow operation by a limitation in bicarbonate resulting from strong homoacetogenic activity.

Download or read book Current Opinion in Biotechnology written by and published by . This book was released on 1995 with total page 982 pages. Available in PDF, EPUB and Kindle. Book excerpt: