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Interactions of Ionic Liquids with Uranium and its Bioreduction

Description: We investigated the influence of ionic liquids (ILs) 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM]{sup +}[PF{sub 6}]{sup -}, N-ethylpyridinium trifluoroacetate [EtPy]{sup +}[CF{sub 3}COO]{sup -} and N-ethylpyridinium tetrafluoroborate [Et-Py]{sup +}[BF{sub 4}]{sup -} on uranium reduction by Clostridium sp. under anaerobic conditions. Potentiometric titration, UV-vis spectrophotometry, LC-MS and EXAFS analyses showed monodentate complexation between uranyl and BF{sub 4}{sup -} PF{sub 6}{sup -}; and bidentate complexation with CF{sub 3}COO{sup -}. Ionic liquids affected the growth of Clostridium sp. as evidenced by decrease in optical density, changes in pH, gas production, and the extent of U(VI) reduction and precipitation of U(IV) from solution. Reduction of U(VI) to U(IV) was observed in the presence of [EtPy][BF{sub 4}] and [BMIM][PF{sub 6}] but not with [EtPy][CF{sub 3}COO].
Date: September 18, 2012
Creator: Zhang, C. & Francis, A.
Partner: UNT Libraries Government Documents Department

ELECTROCHEMICAL CORROSION REPORT FOR TANKS 241-AW-103 & 241-AZ-102 & 241-AN-106 & 241-AN-107 & 241-AY-101 & 241-AY-102

Description: Corrosion rates using supernatant samples retrieved from near the top of the liquid layer were determined for the tanks. Corrosion rates using settled solids (saltcake) were determined. The supernatant samples were tested as received without argon sparging. The settled solid sample segments were extruded under anaerobic condition and kept under a sweep of humidified argon gas during 'the electrochemical corrosion testing. The class of steel used to construct the tank in question was used, and test coupons were allowed to equilibrate for a minimum of 18 hours before a Tafel scan was initiated. The coupons were scanned from -250 mV to +250 mV from the rest or open circuit potential. The corrosion rate is reported along with the corrosion current measurement, open circuit potential, and a chi-square statistic generated by the instrument controlling and analysis algorithm.
Date: August 22, 2007
Creator: JB, DUNCAN
Partner: UNT Libraries Government Documents Department

Stability of uranium incorporated into Fe(hydr)oxides under fluctuating redox conditions

Description: Reaction pathways resulting in uranium bearing solids that are stable (i.e., having limited solubility) under both aerobic and anaerobic conditions will limit dissolved concentrations and migration of this toxin. Here we examine the sorption mechanism and propensity for release of uranium reacted with Fe (hydr)oxides under cyclic oxidizing and reducing conditions. Upon reaction of ferrihydrite with Fe(II) under conditions where aqueous Ca-UO{sub 2}-CO{sub 3} species predominate (3 mM Ca and 3.8 mM CO{sub 3}-total), dissolved uranium concentrations decrease from 0.16 mM to below detection limit (BDL) after 5 to 15 d, depending on the Fe(II) concentration. In systems undergoing 3 successive redox cycles (15 d of reduction followed by 5 d of oxidation) and a pulsed decrease to 0.15 mM CO{sub 3}-total, dissolved uranium concentrations varied depending on the Fe(II) concentration during the initial and subsequent reduction phases - U concentrations resulting during the oxic 'rebound' varied inversely with the Fe(II) concentration during the reduction cycle. Uranium removed from solution remains in the oxidized form and is found both adsorbed on and incorporated into the structure of newly formed goethite and magnetite. Our 15 results reveal that the fate of uranium is dependent on anaerobic/aerobic conditions, aqueous uranium speciation, and the fate of iron.
Date: April 1, 2009
Creator: Stewart, B.D.; Nico, P.S. & Fendorf, S.
Partner: UNT Libraries Government Documents Department

Biotransformation of PuEDTA: Implications to Pu Immobilization

Description: This project integrates three distinct goals to develop a fundamental understanding of the potential fate and disposition of plutonium in sediments that are co-contaminated with EDTA. The three objectives are: (1) Develop thermodynamic data for Pu-EDTA species and determine the dominant mobile form of Pu under anaerobic conditions. (2) Elucidate the mechanism and rates of Pu(IV) and Pu(IV)-EDTA reduction by metal-reducing bacteria and determine where the Pu is located (in solution, biosorbed, bioaccumulated). (3) Enrich and isolate anaerobic EDTA-degrading microorganisms to investigate the anaerobic biodegradation of Pu-EDTA.
Date: June 1, 2006
Creator: Bolton, Harvey, Jr.
Partner: UNT Libraries Government Documents Department

Energetics and kinetics of anaerobic aromatic and fatty acid degradation. Progress report, March 1992--June 1995

Description: Factors affecting the rate and extent of benzoate degradation by anaerobic syntrophic consortia were studied. Cocultures of a syntrophic benzoate degrader, strain SB, with a hydrogen/formate-using sulfate reducer degraded benzoate to a threshold that depended on the amount of substrate and acetate present. The benzoate threshold was not a function of the inhibition of benzoate degradation capacity by acetate or the toxicity of the undissociated form of acetate. Rather, a critical or minimal Gibb`s free energy value may exist where thermodynamic constraints preclude further benzoate degradation. A sensitive assay to detect low formate concentrations was developed to measure the formate levels when the benzoate threshold was reached. We showed that increased acetate concentrations, even when hydrogen and formate levels are low, affects the extent of benzoate degradation, implicating the importance of interspecies acetate transfer. In addition to benzoate, various saturated and unsaturated fatty acids, 2-methylbutyrate, and methyl esters of fatty acids supported growth in coculture with a hydrogen-using partner. SB is the only syntrophic bacterium known to use both benzoate and fatty acids. Phylogenetic analysis showed that SB clustered with sulfate reducers in the delta subclass of the Proteobacteria. SB grew well in coculture with Desulfoarculus baarsii, a sulfate reducer that uses formate but not hydrogen. This unequivocally shows that SB can grow by interspecies formate transfer.
Date: June 23, 1995
Creator: M.J., McInerney
Partner: UNT Libraries Government Documents Department

The utilization of the microflora indigenous to and present in oil-bearing formations to selectively plug the more porous zones thereby increasing oil recovery during waterflooding. Annual report, January 1, 1996--December 30, 1996

Description: This project is a field demonstration of the ability of in-situ indigenous microorganisms in the North Blowhorn Creek Oil Field to reduce the flow of injection water in the more permeable zones thereby diverting flow to other areas of the reservoir and thus increase the efficiency of the waterflooding operation. This effect is to be accomplished by adding microbial nutrients to the injection water. Work on the project is divided into three phases, Planning and Analysis (9 months), Implementation (45 months), and Technology Transfer (12 months). This report covers the third year of work on the project. During Phase I, two wells were drilled in an area of the field where approximately twenty feet of Carter sand were found and appeared to contain oil bypassed by the existing waterflood. Cores from one well were obtained and used in laboratory core flood experiments. The schedule and amounts of nutrients to be employed in the field were formulated on the basis of the results from laboratory core flood experiments.
Date: August 1, 1997
Creator: Brown, L.R. & Vadie, A.A.
Partner: UNT Libraries Government Documents Department


Description: The mechanism of action of p-hydroxybenzoate hydroxylase from Pseudomonas putida, strain M-6, has been investigated. The aromatic substrate analogues, benzoate, p-fluorobenzoate, p-chlorobenzoate, p-nitrobenzoate, p-aminobenzoate, and 6-hydroxynicotinate, are found to be competitive inhibitors. This finding differs from the previously reported noncompetitive behavior in a different buffer system. The optical activity of the enzyme-inhibitor complex is studied. From the kinetic and circular dichroism (CD) measurements, they have found that the carboxyl moiety is necessary and sufficient for the enzyme-substrate binding, whereas the hydroxyl group alone will not lead to binding. There are two classes of inhibitory analogues: one causes changes in CD spectra of the enzyme similar to those evoked by the substrate, and the other does not cause significant changes. the results indicate that more than one mode of enzyme-inhibitor interaction is involved. The CD of the enzyme-NADPH complex under anaerobic conditions suggests that the oxidized enzyme and reduced pyridine nucleotide form a complex, both in the absence and presence of the substrate, p-hydroxybenzoate. Furthermore, evidence for a ternary complex is given.
Date: April 1, 1971
Creator: Teng, Nelson N.H.; Kbtovycz, George.; Calvin, Melvin. & Hosokawa,Keiichi.
Partner: UNT Libraries Government Documents Department


Description: Oxygen is a primary indicator of whether anaerobic reductive dechlorination and similar redox based processes contribute to natural attenuation remedies at chlorinated solvent contaminated sites. Thus, oxygen is a viable indicator parameter for documenting that a system is being sustained in an anaerobic condition. A team of researchers investigated the adaptation of an optical sensor that was developed for oceanographic applications. The optical sensor, because of its design and operating principle, has potential for extended deployment and sensitivity at the low oxygen levels relevant to natural attenuation. The results of the research indicate this tool will be useful for in situ long-term monitoring applications, but that the traditional characterization tools continue to be appropriate for characterization activities.
Date: October 12, 2006
Creator: Millings, Margaret R.; Riha, Brian D.; Hyde, W. Keith; Vangelas, Karen & Looney, Brian B.
Partner: UNT Libraries Government Documents Department

Experimental Investigation of Microbially Induced Corrosion of Test Samples and Effect of Self-Assembled Hydrophobic Monolayers. Exposure of Test Samples to Continuous Microbial Cultures, Chemical Analysis, and Biochemical Studies

Description: The study of biocorrosion of aluminum and beryllium samples were performed under conditions of continuous fermentation of thermophilic anaerobic microorganisms of different groups. This allowed us to examine the effect of various types of metabolic reactions of reduction-oxidation proceeding at different pH and temperatures under highly reduced conditions on aluminum and beryllium corrosion and effect of self-assembled hydrophobic monolayers.
Date: September 30, 1998
Creator: Laurinavichius, K. S.
Partner: UNT Libraries Government Documents Department


Description: Biosurfactants enhance hydrocarbon biodegradation by increasing apparent aqueous solubility or affecting the association of the cell with poorly soluble hydrocarbon. Here, we show that a lipopeptide biosurfactant produced by Bacillus mojavensis strain JF-2 mobilized substantial amounts of residual hydrocarbon from sand-packed columns when a viscosifying agent and a low molecular weight alcohol were present. The amount of residual hydrocarbon mobilized depended on the biosurfactant concentration. One pore volume of cell-free culture fluid with 900 mg/l of the biosurfactant, 10 mM 2,3-butanediol and 1000 mg/l of partially hydrolyzed polyacrylamide polymer mobilized 82% of the residual hydrocarbon. Consistent with the high residual oil recoveries, we found that the bio-surfactant lowered the interfacial tension (IFT) between oil and water by nearly 2 orders of magnitude compared to typical IFT values of 28-29 mN/m. Increasing the salinity increased the IFT with or without 2,3-butanediol present. The lowest interfacial tension observed was 0.1 mN/m. The lipopeptide biosurfactant system may be effective in removing hydrocarbon contamination sources in soils and aquifers and for the recovery of entrapped oil from low production oil reservoirs. Previously, we reported that Proteose peptone was necessary for anaerobic growth and biosurfactant production by B. mojavensis JF-2. The data gathered from crude purification of the growth-enhancing factor in Proteose peptone suggested that it consisted of nucleic acids; however, nucleic acid bases, nucleotides or nucleosides did not replace the requirement for Proteose Peptone. Further studies revealed that salmon sperm DNA, herring sperm DNA, Echerichia coli DNA and synthetic DNA replaced the requirement for Proteose peptone. In addition to DNA, amino acids and nitrate were required for anaerobic growth and vitamins further improved growth. We now have a defined medium that can be used to manipulate growth and biosurfactant production. As an initial step in the search for a better biosurfactant-producing microorganism, 157 bacterial ...
Date: June 26, 2003
Creator: McInerney, M.J.; Knapp, R.M.; D.P. Nagle, Jr.; Duncan, Kathleen; Youssef, N.; Folmsbee, M.J. et al.
Partner: UNT Libraries Government Documents Department

Microbiology and physiology of anaerobic fermentation of cellulose. Progress report (4/30/91--4/30/92) and outline of work for the period 9/1/92--9/1/93

Description: The authors are continuing their efforts to partly dissociate the cellulolytic enzyme complex of C. thermocellum. This complex named cellulosome (also existing as polycellulosome) consists of perhaps as many as 26 different subunits. It is extremely resistant to dissociation and denaturation. Treatments with urea and SDS have little effect unless the latter treatment is at high temperature. Significantly, some of the subunits after SDS dissociation have CMCase (endoglucanase) activity but no activity toward crystalline cellulose. The only reported success of hydrolysis of crystalline cellulose by cellulosomal subunits is by Wu et al. who isolated two protein fractions labeled SL and SS which when combined exhibit a low (about 1% of the original cellulosome) activity toward crystalline cellulose. The long standing goal is still to determine the activities of the individual subunits, to characterize them, to find out how they are associated in the cellulosome, and to establish the minimum number of subunits needed for efficient hydrolysis of crystalline cellulose. This report also presents the results of experiments on cellulose hydrolysis in aerobic fungi, as well as other anaerobic bacteria.
Date: December 31, 1992
Creator: Ljungdahl, L.G.
Partner: UNT Libraries Government Documents Department

Induced polarization response of microbial induced sulfideprecipitation

Description: A laboratory scale experiment was conducted to examine the use of induced polarization and electrical conductivity to monitor microbial induced sulfide precipitation under anaerobic conditions in sand filled columns. Three columns were fabricated; one for electrical measurements, one for geochemical sampling and a third non-inoculated column was used as a control. A continual upward flow of nutrients and metals in solution was established in each column. Desulfovibrio vulgaris microbes were injected into the middle of the geochemical and electrical columns. Iron and zinc sulfides precipitated along a microbial action front as a result of sulfate reduction due by Desulfovibrio vulgaris. The precipitation front initially developed near the microbial injection location, and subsequently migrated towards the nutrient inlet, as a result of chemotaxis by Desulfovibrio vulgaris. Sampling during and subsequent to the experiment revealed spatiotemporal changes in the biogeochemical measurements associated with microbial sulfate reduction. Conductivity measurements were insensitive to all biogeochemical changes occurred within the column. Changes in the IP response (of up to 14 mrad)were observed to coincide in place and in time with the active microbe respiration/sulfide precipitation front as determined from geochemical sampling. The IP response is correlated with the lactate concentration gradient, an indirect measurement of microbial metabolism, suggesting the potential of IP as a method for monitoring microbial respiration/activity. Post experimental destructive sample analysis and SEM imaging verified the geochemical results and supported our hypothesis that microbe induced sulfide precipitation is directly detectable using electrical methods. Although the processes not fully understood, the IP response appears to be sensitive to this anaerobic microbial precipitation, suggesting a possible novel application for the IP method.
Date: June 4, 2004
Creator: Ntarlagiannis, Dimitrios; Williams, Kenneth Hurst; Slater, Lee & Hubbard, Susan
Partner: UNT Libraries Government Documents Department


Description: Microorganisms can affect the stability and mobility of the actinides U, Pu, Cm, Am, Np, and the fission products Tc, I, Cs, Sr, released from nuclear fuel reprocessing plants. Under appropriate conditions, microorganisms can alter the chemical speciation, solubility and sorption properties and thus could increase or decrease the concentrations of radionuclides in solution and the bioavailability. Dissolution or immobilization of radionuclides is brought about by direct enzymatic action or indirect non-enzymatic action of microorganisms. Although the physical, chemical, and geochemical processes affecting dissolution, precipitation, and mobilization of radionuclides have been investigated, we have only limited information on the effects of microbial processes. The mechanisms of microbial transformations of the major and minor actinides and the fission products under aerobic and anaerobic conditions in the presence of electron donors and acceptors are reviewed.
Date: October 18, 2006
Creator: FRANCIS,A.J.
Partner: UNT Libraries Government Documents Department

Arsenic chemistry in soils and sediments

Description: Arsenic is a naturally occurring trace element that poses a threat to human and ecosystem health, particularly when incorporated into food or water supplies. The greatest risk imposed by arsenic to human health results from contamination of drinking water, for which the World Health Organization recommends a maximum limit of 10 {micro}g L{sup -1}. Continued ingestion of drinking water having hazardous levels of arsenic can lead to arsenicosis and cancers of the bladder, skin, lungs and kidneys. Unfortunately, arsenic tainted drinking waters are a global threat and presently having a devastating impact on human health within Asia. Nearly 100 million people, for example, are presently consuming drinking water having arsenic concentrations exceeding the World Health Organization's recommended limit (Ahmed et al., 2006). Arsenic contamination of the environment often results from human activities such as mining or pesticide application, but recently natural sources of arsenic have demonstrated a devastating impact on water quality. Arsenic becomes problematic from a health perspective principally when it partitions into the aqueous rather than the solid phase. Dissolved concentrations, and the resulting mobility, of arsenic within soils and sediments are the combined result of biogeochemical processes linked to hydrologic factors. Processes favoring the partitioning of As into the aqueous phase, potentially leading to hazardous concentrations, vary extensively but can broadly be grouped into four categories: (1) ion displacement, (2) desorption (or limited sorption) at pH values > 8.5, (3) reduction of arsenate to arsenite, and (4) mineral dissolution, particularly reductive dissolution of Fe and Mn (hydr)oxides. Although various processes may liberate arsenic from solids, a transition from aerobic to anaerobic conditions, and commensurate arsenic and iron/manganese reduction, appears to be a dominant, but not exclusive, means by which high concentrations of dissolved arsenic are generated. Within the subsequent sections of this chapter, we explore and describe ...
Date: October 15, 2009
Creator: Fendorf, S.; Nico, P.; Kocar, B.D.; Masue, Y. & Tufano, K.J.
Partner: UNT Libraries Government Documents Department

Evaluation of the effects of various culture condition on Cr (VI) reduction by Shewanella oneidensis MR-1 in a novel high-throughputmini-bioreactor

Description: The growth and Cr(VI) reduction by Shewanella oneidensisMR-1 was examined using a mini-bioreactor system that independentlymonitors and controls pH, dissolved oxygen, and temperature for each ofits 24, 10-mL reactors. Independent monitoring and control of eachreactor in the cassette allows the exploration of a matrix ofenvironmental conditions known to influence S. oneidensis chromiumreduction. S. oneidensis MR-1 grew in minimal medium without amino acidor vitamin supplementation under aerobic conditions but required serineand glycine supplementation under anaerobic conditions. Growth wasinhibited by dissolved oxygen concentrations>80 percent. Lactatetransformation to acetate was enhanced by low concentration of dissolvedoxygen during the logarithmic growth phase. Between 11 and 35oC, thegrowth rate obeyed the Arrhenius reaction rate-temperature relationship,with a maximum growth rate occurring at 35oC. S. oneidensis MR-1 was ableto grow over a wide range of pH (6-9). At neutral pH and temperaturesranging from 30-35oC, S. oneidensis MR-1 reduced 100 mu M Cr(VI) toCr(III) within 20 minutes in the exponential growth phase, and the growthrate was not affected by the addition of chromate; it reduced chromateeven faster at temperatures between 35 and 39oC. At low temperatures(<25oC), acidic (pH<6.5), or alkaline (pH>8.5) conditions, 100mu M Cr(VI) strongly inhibited growth and chromate reduction. Themini-bioreactor system enabled the rapid determination of theseparameters reproducibly and easily by performing very few experiments.Besides its use for examining parameters of interest to environmentalremediation, the device will also allow one to quickly assess parametersfor optimal production of recombinant proteins or secondarymetabolites
Date: March 16, 2006
Creator: Tang, Yinjie J.; Laidlaw, David; Gani, Kishen & Keasling, Jay D.
Partner: UNT Libraries Government Documents Department

Corrosion-induced gas generation in a nuclear waste repository: Reactive geochemistry and multiphase flow effect

Description: Corrosion of steel canisters, stored in a repository for spent fuel and high-level nuclear wastes, leads to the generation and accumulation of hydrogen gas in the backfilled emplacement tunnels, which may significantly affect long-term repository safety. Previous studies used H{sub 2} generation rates based on the volume of the waste or canister material and the stoichiometry of the corrosion reaction. However, iron corrosion and H{sub 2} generation rates vary with time, depending on factors such as amount of iron, water availability, water contact area, and aqueous and solid chemistry. To account for these factors and feedback mechanisms, we developed a chemistry model related to iron corrosion, coupled with two-phase (liquid and gas) flow phenomena that are driven by gas-pressure buildup associated with H{sub 2} generation and water consumption. Results indicate that by dynamically calculating H{sub 2} generation rates based on a simple model of corrosion chemistry, and by coupling this corrosion reaction with two-phase flow processes, the degree and extent of gas pressure buildup could be much smaller compared to a model that neglects the coupling between flow and reactive transport mechanisms. By considering the feedback of corrosion chemistry, the gas pressure increases initially at the canister, but later decreases and eventually returns to a stabilized pressure that is slightly higher than the background pressure. The current study focuses on corrosion under anaerobic conditions for which the coupled hydrogeochemical model was used to examine the role of selected physical parameters on the H{sub 2} gas generation and corresponding pressure buildup in a nuclear waste repository. The developed model can be applied to evaluate the effect of water and mineral chemistry of the buffer and host rock on the corrosion reaction for future site-specific studies.
Date: October 15, 2008
Creator: Xu, T.; Senger, R. & Finsterle, S.
Partner: UNT Libraries Government Documents Department

Results an data on the growth of the microorganisms

Description: The study of biocorrosion of aluminum and its alloy was performed under conditions of continuous fermentation of thermophilic anaerobic microorganisms of different groups. This allowed us to examine the effect of various types of metabolic reactions of reduction-oxidation proceeding at different pH and temperatures under highly reduced conditions on aluminum corrosion. Besides, the experiments were performed where the part of the standard sample was exposed under strictly anaerobic conditions with an active microbiological process, and the second half was exposed under aerobic conditions. Thus the sample was exposed in gradient of oxidized-reduced conditions.
Date: October 9, 1995
Creator: Laurinavichius, K.S.
Partner: UNT Libraries Government Documents Department

Development of monitoring and control technology based on trace gas monitoring. Final report

Description: Trace gases are generated by many biological reactions. During anaerobic decomposition, trace levels of hydrogen (H{sub 2}) and carbon monoxide (CO) gases are produced. It was shown previously that these trace gases are intrinsically related to the biochemical reactions occurring and, therefore, offer promise for on-line process monitoring and control. This work was designed to test how effectively hydrogen and CO could be to monitor high-rate anaerobic systems that has significant mass transfer and complex hydraulics. An experimental program was designed to examine the behavior of an upflow anaerobic sludge blanket (UASB) reactor system under steady state and in response to organic loading perturbations. The responses of trace gases CO and H{sub 2} were tracked using an on-line, real-time gas-monitoring system linked to a computer-controlled data acquisition package. Data on conventional process parameters such as pH, chemical oxygen demand (COD), volatile fatty acids (VFAs) were concurrently collected. Monitoring of conventional process indicators (i.e., pH, VFA, gas production) and trace gas (H{sub 2} and CO) indicators was conducted using a matrix of nine different steady-state OLRs (4-23 kg COD/m{sup 3} -d) and system HRTs (0.5 to 2.5 days) was performed to determine any correlation among the indicators. Of OLR, HRT, and influent COD, only OLR had any significant influence on the process indicators examined. All parameters except methane increased with increases in OLR; methane decreased with increased OLR. The OLR and gas production rate (GP) were observed to be linearly correlated.
Date: July 1, 1997
Creator: Liebowitz, B.
Partner: UNT Libraries Government Documents Department

Deployment Plan for Bioremediation and Natural Attenuation for In Situ Restoration of Chloroethene-Contaminated Groundwater

Description: This deployment plan describes a project funded by the Accelerated Site Technology Deployment Program of the U.S. Department of Energy (DOE). The objective is to facilitate deployment of enhanced in situ bioremediation (ISB) an monitored natural attenuation (MNA) or chloroethene-contaminated groundwater to DOE sites. Enhanced ISB accelerates dechlorination of chloroethenes under anaerobic conditions by providing nutrients to the microbial community. Natural attenuation does not require nutrient addition. Enhanced ISB in the upgradient portion of a contaminant plume couples with MNA in the downgradient portion is being implemented at Test Area North (TAN) at the Idaho National Engineering and Environmental Laboratory. Selected DOE sites will be screened to assess their suitability for enhanced ISB/MNA. Tasks include: (1) characterization of the TAN microbial community and correlation of community characteristics with chloroethene degradation ability, (2) installation of wells to facilitate evaluation of MNA at TAN, (3) monitoring to better delineate MNA at TAN, and (4) screening of selected other DOE sites for suitability of ISB/MNA, and limited supplemental characterization. Data evaluation will provide a sound technical basis for decision makers to consider use of enhanced ISB and MNA, alone or together, as remedial technologies for these sites.
Date: March 1, 1999
Creator: Peterson, L.N.; Starr, R.C.; Sorenson, K.S.; Smith, R.W. & Phelps, T.J.
Partner: UNT Libraries Government Documents Department

Mathematical modeling of the effects of aerobic and anaerobic chelate bioegradation on actinide speciation.

Description: Biodegradation of natural and anthropogenic chelating agents directly and indirectly affects the speciation, and, hence, the mobility of actinides in subsurface environments. We combined mathematical modeling with laboratory experimentation to investigate the effects of aerobic and anaerobic chelate biodegradation on actinide [Np(IV/V), Pu(IV)] speciation. Under aerobic conditions, nitrilotriacetic acid (NTA) biodegradation rates were strongly influenced by the actinide concentration. Actinide-chelate complexation reduced the relative abundance of available growth substrate in solution and actinide species present or released during chelate degradation were toxic to the organisms. Aerobic bio-utilization of the chelates as electron-donor substrates directly affected actinide speciation by releasing the radionuclides from complexed form into solution, where their fate was controlled by inorganic ligands in the system. Actinide speciation was also indirectly affected by pH changes caused by organic biodegradation. The two concurrent processes of organic biodegradation and actinide aqueous chemistry were accurately linked and described using CCBATCH, a computer model developed at Northwestern University to investigate the dynamics of coupled biological and chemical reactions in mixed waste subsurface environments. CCBATCH was then used to simulate the fate of Np during anaerobic citrate biodegradation. The modeling studies suggested that, under some conditions, chelate degradation can increase Np(IV) solubility due to carbonate complexation in closed aqueous systems.
Date: March 19, 1998
Creator: Banaszak, J.E.; VanBriesen, J.; Rittmann, B.E. & Reed, D.T.
Partner: UNT Libraries Government Documents Department

Hemicellulases from the ethanologenic thermophile, Thermoanaerobacter ethanolicus and related anaerobic thermophiles. Final report, September 1992--June 1996

Description: The short term goals of this application were to characterize hemicellulases from anaerobic thermophiles on the biochemical and molecular level to extend the presently limited knowledge of hemicellulases in anaerobic thermophilic bacteria. This objective includes the following tasks: (1) Traditional purification and biochemical/biophysical characterization of xylanases from the newly isolated, slightly alkalitolerant strain NDF190, and the slightly acid-tolerant strain YS485, both with high xylanolytic activities, and of the 4-O-methyl glucuronidase and arabinosidase from strain NDF190 and the acetyl (xylan) esterase from T. ethanolicus. This also includes determining the N-terminal sequences and obtaining gene probes. (2) Elucidation of the regulation of hemicellulolytic enzymes in anaerobic thermophiles. (3) To clone into E. coli and identify the multiplicity of the enzymes involved in hemicellulose degradation by T. ethanolicus and other suitable organisms. (4) To purify and characterize the recombinant enzymes with the goal of identifying the best enzymes for cloning into the ethanologenic T. ethanolicus to obtain an optimized hemicellulose utilization by this bacterium.
Date: September 1, 1998
Creator: Wiegel, J.
Partner: UNT Libraries Government Documents Department

Advanced Experimental Analysis of Controls on Microbial Fe(III) Oxide Reduction - Final Report - 09/16/1996 - 03/16/2001

Description: Considering the broad influence that microbial Fe(III) oxide reduction can have on subsurface metal/organic contaminant biogeochemistry, understanding the mechanisms that control this process is critical for predicting the behavior and fate of these contaminants in anaerobic subsurface environments. Knowledge of the factors that influence the rates of growth and activity of Fe(III) oxide-reducing bacteria is critical for predicting (i.e., modeling) the long-term influence of these organisms on the fate of contaminants in the subsurface, and for effectively utilizing Fe(III) oxide reduction and associated geochemical affects for the purpose of subsurface metal/organic contamination bioremediation. This research project will refine existing models for microbiological and geochemical controls on Fe(III) oxide reduction, using laboratory reactor systems that mimic, to varying degrees, the physical and chemical conditions of the subsurface. Novel experimental methods for studying the kinetics of microbial Fe(III) oxide reduction and measuring growth rates of Fe(III) oxide-reducing bacteria will be developed. These new methodologies will be directly applicable to studies on subsurface contaminant transformations directly coupled to or influenced by microbial Fe(III) oxide reduction.
Date: March 16, 2001
Creator: Roden, Eric E.
Partner: UNT Libraries Government Documents Department


Description: Direct and indirect effects of microorganisms on technetium insolubilization in water covering waterlogged soils were studied. Seven soils were waterlogged and then the water covering the soils were collected for further tracer experiments. The samples in contact with air were incubated with 95mTcO4--at 25 C for 4 to 5 days. After incubation, the samples were sequentially separated into four fractions: one insoluble fraction (&gt; 0.2 {micro}m) and three soluble fractions (TcO4 -, cationic, and other forms). The radioactivity of 95mTc in each fraction was measured with a NaI (Tl) scintillation counter. The insolubility of Tc was observed in the untreated samples. The maximum insolubilization radioactivity was 37% of the total radioactivity in P38, which was collected from a paddy field, gray lowland soil. Microscopic observations revealed that bacteria were the dominant species in the insoluble fraction of P38. For the other samples, less than 9% of the Tc was found in insoluble form. In order to clarify biological and nonbiological factor affecting the insolubility, a reducing agent or nutrients were added to the P38 sample. The amount of insoluble Tc was enhanced by the addition of nutrients, while the addition of the reducing agent resulted in a dramatic decrease in the amount of the insoluble Tc. Most of the 95mTcO4 - added to the filtered or autoclaved samples was present in the form of the pertechnetate anion, even in P38. The filtered and autoclaved samples contained metabolites and dead cell particles, respectively. These materials, therefore, did not affect the physicochemical changes in Tc. These results suggest that specific bacteria having the ability to render Tc insoluble even under not strictly anaerobic conditions directly contribute to the insolubility of Tc.
Date: February 27, 2003
Creator: Ishii, N.; Tagami, K. & Uchida, S.
Partner: UNT Libraries Government Documents Department