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1

Insights into dechlorination of PCE and TCE from carbon isotope fractionation by vitamin B12  

NASA Astrophysics Data System (ADS)

Reductive dechlorination of perchloroethylene (PCE) and trichloroethylene (TCE) by vitamin B12 is both a potential remediation technique and an analogue of the microbial reductive dechlorination reaction. Stable carbon isotopic analysis, an effective and powerful tool for the investigation and monitoring of contaminant remediation, was used to characterize the isotopic effects of reductive dechlorination of PCE and TCE by vitamin B12 in laboratory microcosms. 10 mg/L vitamin B12 degraded greater than 90% of an initial concentration of PCE of 20 mg/L. TCE, the primary product of PCE degradation, accounted for between 64 - 72% of the PCE degraded. In experiments with TCE, 147 mg/L vitamin B12 degraded greater than 90% of an initial concentration of TCE of 20 mg/L. Cis-dichloroethene (cDCE), the primary product of TCE degradation, accounted for between 30 - 35% of the TCE degraded. Degradation of both PCE and TCE exhibited first order kinetics. Strong isotopic fractionation of the reactant PCE and of the reactant TCE was observed over the course of degradation. This fractionation could be described by a Rayleigh model with enrichment factors between -16.5 ppm and -15.8 ppm for PCE, and -17.2 ppm and -16.6 ppm for TCE. Fractionation was similar in all four experiments, with a mean enrichment factor of -16.5 +/- 0.6 ppm. These large enrichment factors indicate that isotopic analysis can be used to assess the occurrence of dechlorination of PCE and TCE by vitamin B12 in remediation situations. Significantly, the Rayleigh model could be used to predict the isotopic compositions of the major products of the reaction as well as the reactant, notwithstanding the lack of complete mass balance observed between product and reactant. This evidence suggests that isotopic fractionation is taking place during complexation of the chlorinated ethenes to vitamin B12, as has been suggested for reductive dechlorination by zero valent iron. The differences between e for this reaction and those observed for microbial biodegradation of the chlorinated ethenes suggest that there may be differences in the rate determining step for these two processes. Determining which steps are rate determining during degradation may allow optimization of contaminant remediation.

Slater, G.; Sherwood Lollar, B.; Lesage, S.; Brown, S.

2003-04-01

2

PCE/TCE DEGRADATION USING MULCH BIOWALLS  

EPA Science Inventory

A passive reactive barrier (Biowall) was installed at the OU-1 site at Altus Air Force Base, Oklahoma to treat TCE contamination in ground water from a landfill. Depth to ground water varies from 1.8 to 2.4 meters below land surface. To intercept and treat the plume of contamin...

3

ROLE OF PHARMACOKINETIC MODELING IN RISK ASSESSMENT -- PERCHLOROETHYLENE (PCE) AS AN EXAMPLE  

EPA Science Inventory

Available metabolic and pharmacokinetic data on perchloroethylene (PCE) are used as a basis for discussion of the use of such data in quantitative risk assessment. he emphasis is on methodologies for improving risk assessment rather than on the risk assessment of PCE per se. he d...

4

UPDATED CARCINOGENICITY ASSESSMENT FOR TETRACHLOROETHYLENE (PERCHLOROETHYLENE, PERC, PCE): ADDENDUM TO THE HEALTH ASSESSMENT DOCUMENT FOR TETRACHLOROETHYLENE (PERCHLOROETHYLENE). EXTERNAL REVIEW DRAFT  

EPA Science Inventory

The Office of Health and Environmental Assessment has prepared the addendum to serve as a source document for EPA use. The addendum updates EPA's July 1985 Health Assessment Document for Tetrachloroethylene (Perchloroethylene, PERC, PCE) by providing a review of the findings of t...

5

Novel Chemical Detection Strategies for TCE and PCE  

SciTech Connect

Results describing two new applications of cavity ring-down spectroscopy (CRDS) will be discussed: (1) detection of TCE and PCE by refractive-index change using surface-plasmon-resonance (SPR)-enhanced CRDS, and (2) C-H overtone detection of TCE by evanescent wave CRDS (EW -CRDS) with a determination of absolute adsorbate surface coverage. The SPR-enhanced CRDS measurements show a minimum detectable concentration of 70 nanomol/L and 20 nanomo l/L for TCE and PCE, respectively, based on a one minute response time at 555 nm. The EW-CRDS measurements use the first C-H overtone of TCE occurring around 1640 nm. Spectra for both surface and gas -phase species are obtained in the evanescent wave. Employing the absolute absorption cross section for the C-H overtone of TCE obtained from gas-phase CRDS measurements, the adsorbate spectrum and corresponding absolute surface number density are determined. The requisite measure of molecular orientation is provided by the polarization dependence of the surface spectrum.

Pipino, Andrew C.R.

2003-09-10

6

Evaluating an AOP for TCE and PCE removal  

Microsoft Academic Search

A full-scale evaluation of an advanced oxidation process (AOP) involving the use of ozone (O?) and hydrogen peroxide (H?O?) at a 126-L\\/s (2,000-gpm) flow rate was completed in a plug-flow hydraulic regime by the Los Angeles (Calif.) Department of Water and Power. This facility is the first full-scale AOP for trichloroethylene (TCE) and tetrachloroethylene (PCE) treatment in the United States,

Ali A. Karimi; Jeremy A. Redman; William H. Glaze; Gary F. Stolarik

1997-01-01

7

Soil Vapor Extraction of PCE/TCE Contaminated Soil  

SciTech Connect

The A/M Area of the Savannah River Site soil and groundwater is contaminated with tetrachloroethylene (PCE) and trichloroethylene (TCE). Contamination is the result of previous waste disposal practices, once considered state-of-the-art. Soil Vapor Extraction (SVE) units have been installed to remediate the A/M Area vadose zone. SVE is a proven in-situ method for removing volatile organics from a soil matrix with minimal site disturbance. SVE alleviates the infiltration of contaminants into the groundwater and reduces the total time required for groundwater remediation. Lessons learned and optimization of the SVE units are also discussed.

Bradley, J.M. [Westinghouse Savannah River Company, AIKEN, SC (United States); Morgenstern, M.R. [Bechtel, , ()

1998-08-01

8

Solubilization and degradation of perchloroethylene (PCE) in cationic and nonionic surfactant solutions.  

PubMed

Solubilization of perchloroethylene (PCE) in a nonionic (Triton X-100) and a cationic (cetyltrimethylammonium bromide (CTAB)) surfactant solutions and the degradation of surfactant solubilized PCE using fine to nanosize Fe and bi-metallic Fe-Ni particles were investigated. Micelle partition coefficients (Km) and molar solubility ratio (MSR) for PCE in 10 g/L of surfactant solutions have been quantified and the solubility of PCE (100 mg/L in water) in the surfactant solutions increased by about ten fold. Of the two surfactants studied, Triton X-100 solubilized the higher amount of PCE per gram of surfactant. To degrade solubilized PCE, both iron and bimetallic Fe-Ni particles were used in continuously stirred batch reactors. The iron and bi-metallic particles were synthesized using the solution method and the particles were characterized using the SEM, EDS, TEM and XRD. The PCE solubilized up to 500 mg/L in both surfactant solutions were totally degraded at various rates by 200 g/L of bi-metallic Fe-Ni particles in less than 20 hr, which is the highest concentration of PCE degraded in the shortest time compared to data in the literature. The degradations of PCE solubilized in surfactant solutions were represented by nonlinear kinetic relationships which depended on the type of surfactant used for solubilizing the PCE. PMID:22128529

Harendra, Sivaram; Vipulanandan, Cumaraswamy

2011-01-01

9

Kinetics and modeling of reductive dechlorination at high PCE and TCE concentrations  

Microsoft Academic Search

Two biokinetic models employing the Michaelis- Menten equation for anaerobic reductive dechlorination of tetrachloroethylene (PCE) and trichloroethylene (TCE) were developed. The models were compared with results from batch kinetic tests conducted over a wide range of PCE and TCE concentrations with two different dechlorin- ating cultures. One model applies Michaelis-Menten ki- netics with competitive inhibition among chlorinated aliphatic hydrocarbons (CAHs),

Seungho Yu; Lewis Semprini

2004-01-01

10

The Removal of Tri (TCE) and Tetrachloroethylene (PCE) from Aqueous Solution using High Energy Electrons  

Microsoft Academic Search

Trichloroethylene (TCE) and tetrachloroethylene (PCE) are common groundwater contaminants that persist inithe environment. An innovative treatment process employing high energy electron beam irradiation has been shown to be an effective process for treating TCE- or PCE-contaminated water, wastewater, and water containing suspended solids.Experiments conducted at the Electron Beam Research Facility, Miami, Florida, have led to a better understanding of the

William J. Cooper; David E. Meacham; Michael G. Nickelsen; Kaijun Lin; David B. Ford; Charles N. Kuruczand; Thomas D. Waite

1993-01-01

11

Advanced Oxidation Processes for Treating Groundwater Contaminated With TCE and PCE: Laboratory Studies  

Microsoft Academic Search

Oxidation of trichloroethylene (TCE) and tetrachloroethylene (PCE) with various dosages of ozone or ozone plus hydrogen peroxide was studied in laboratory experiments. The results show that hydrogen peroxide accelerates the oxidation of TCE and PCE by ozone. At peroxide-to-ozone dosage ratios of > 0.7 (w\\/w), the process appears to be mass transfer limited. High levels of bicarbonate ion in the

William H. Glaze; Joon-Wun Kang

1988-01-01

12

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction  

SciTech Connect

A pre-combustion coal desulfurization process at 120{degree}C using perchloroethylene (PCE) to remove up to 70% of the organic sulfur has been developed by the Midwest Ore Processing Co. (MWOPC). However, this process has not yet proven to be as successful with Illinois coals as it has for Ohio and Indiana coals. The organic sulfur removal has been achieved only with highly oxidized Illinois coals containing high sulfatic sulfur. A logical explanation for this observation is vital to successful process optimization for the use of Illinois coals. In addition, the high levels of organic sulfur removals observed by the MWOPC may be due to certain errors involved in the ASTM data interpretation; this needs verification. For example, elemental sulfur extracted by the PCE may be derived from pyrite oxidation during coal pre-oxidation, but it may be interpreted as organic sulfur removed by the PCE using ASTM analysis. The goals of this research are: (1) to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE desulfurization process reported by the MWOPC, (2) to verify the forms-of-sulfur determination using the ASTM method for the PCE process evaluation, and (3) to determine the suitability of Illinois coals for use in the PCE desulfurization process. This project involves the Illinois State Geological Survey (ISGS), Eastern Illinois University (EIU), the University of Illinois-Urbana/Champaign (UI-UC), and the University of Kentucky, Lexington (UK). This is the first year of a two-year project.

Chou, M.I.M.

1991-01-01

13

COMPLETE NATURAL ATTENUATION OF A PCE AND TCE PLUME AFTER SOURCE REMOVAL  

EPA Science Inventory

Disposal of the chlorinated solvents PCE and TCE at the Twin Cities Army Ammunition Plant (TCAAP) resulted in the contamination of groundwater in a shallow, unconsolidated sand aquifer. The resulting plume had moved over 1000 feet from the disposal source area and had impacted p...

14

FY00 Phytoremediation of Trichloroethylene and Perchloroethylene in the Southern Sector of SRS  

SciTech Connect

This treatability study addresses the fate of volatile organic contaminants (VOCs) in an experiment that simulates a vegetated seepline supplied with trichloroethylene (TCE) and perchloroethylene (PCE) -contaminated groundwater. The primary objective is to determine how the trees uptake TCE and PCE, accumulate it, and/or transform it.

Brigmon, R.L.

2000-12-15

15

Effects of alcohols, anionic and nonionic surfactants on the reduction of PCE and TCE by zero-valent iron.  

PubMed

The effects of surfactants, sodium dodecyl sulfate (SDS) and Triton X-a00 (TX), and alcohols (methanol, ethanol, and propanol) on the dehalogenation of TCE and PCE by zero-valent iron were examined. Surface concentrations of PCE and TCE on the iron were dependent on aqueous surfactant concentrations. At concentrations above the CMC, sorbed halocarbon concentrations declined and concentrations associated with solution phase micelles increased. The anionic surfactant SDS ([SDS] < CMC) did not affect reduction rates, until the CMC was exceeded after which reactivity decreased, possibly due to sequestering of the TCE and PCE in mobile micelles. The nonionic TX showed a mixed effect on reactivity, increasing the PCE reduction rate, but not affecting TCE removal. Production of TCE from PCE increased in the presence of TX. Similar experiments showed that methanol, ethanol, and propanol inhibited reduction of TCE and PCE by metallic iron. Zero-valent iron may be useful in recycling soil washing effluents contaminated with TCE and PCE. PMID:11317892

Loraine, G A

2001-04-01

16

Effects of alcohols, anionic and nonionic surfactants on the reduction of pce and tce by zero-valent iron  

Microsoft Academic Search

The effects of surfactants, sodium dodecyl sulfate (SDS) and Triton X-a00 (TX), and alcohols (methanol, ethanol, and propanol) on the dehalogenation of TCE and PCE by zero-valent iron were examined. Surface concentrations of PCE and TCE on the iron were dependent on aqueous surfactant concentrations. At concentrations above the CMC, sorbed halocarbon concentrations declined and concentrations associated with solution phase

Gregory A Loraine

2001-01-01

17

Kinetic modeling and simulation of PCE and TCE removal in aqueous solutions by electron-beam irradiation  

Microsoft Academic Search

The irradiation of aqueous solutions of TCE and PCE using a high-energy electron-beam results in the rapid decomposition of both chemicals. It is known that both TCE and PCE react with the aqueous electron and the hydroxyl radical with bimolecular rate constants greater than 109M?1s?1 for each reaction. The fact that high-energy electrons produce significant concentrations of both eaq? and

Michael G. Nickelsen; William J. Cooper; David A. Secker; Louis A. Rosocha; Charles N. Kurucz; Thomas D. Waite

2002-01-01

18

Kinetic modeling and simulation of PCE and TCE removal in aqueous solutions by electron-beam irradiation  

Microsoft Academic Search

The irradiation of aqueous solutions of TCE and PCE using a high-energy electron-beam results in the rapid decomposition of both chemicals. It is known that both TCE and PCE react with the aqueous electron and the hydroxyl radical with bimolecular rate constants greater than 109M-1s-1 for each reaction. The fact that high-energy electrons produce significant concentrations of both eaq- and

Michael G. Nickelsen; William J. Cooper; David A. Secker; Louis A. Rosocha; Charles N. Kurucz; Thomas D. Waite

2002-01-01

19

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. Annual report, September 1, 1991--August 31, 1992.  

National Technical Information Service (NTIS)

The Midwest Ore Processing Co. (MWOPC) has reported a precombustion coal desulfurization process using perchloroethylene (PCE) at 120(degree)C to remove up to 70% of the organic sulfur. However, this process has not been proven to be as successful with Il...

M. I. M. Chou J. M. Lytle R. R. Ruch C. W. Kruse C. Chaven

1992-01-01

20

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. Annual report, September 1, 1991August 31, 1992  

Microsoft Academic Search

The Midwest Ore Processing Co. (MWOPC) has reported a precombustion coal desulfurization process using perchloroethylene (PCE) at 120°C to remove up to 70% of the organic sulfur. However, this process has not been proven to be as successful with Illinois coals as it has been for Ohio and Indiana coals. Also, the high levels of organic sulfur removals observed by

M. I. M. Chou; J. M. Lytle; R. R. Ruch; C. W. Kruse; C. Chaven; K. C. Hackley; R. E. Hughes; R. D. Harvey; J. K. Frost; D. H. Buchanan; J. W. Stucki; G. P. Huffman; F. E. Huggins; D. D. Banerjee

1992-01-01

21

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. Technical report, December 1, 1991--February 29, 1992  

SciTech Connect

A pre-combustion coal desulfurization process at 120{degree}C using perchloroethylene (PCE) to remove up to 70% of the organic sulfur has been developed by the Midwest Ore Processing Co. (MWOPC). However, this process has not yet proven to be as successful with Illinois coals as it has for Ohio and Indiana coals. In addition, the high levels of organic sulfur removals observed by the MWOPC may be due to certain errors involved in the ASTM data interpretation; this needs verification. For example, elemental sulfur extracted by the PCE may be derived from pyrite oxidation during coal preoxidation, but it may be interpreted as organic sulfur removed by the PCE using ASTM analysis. The purposes of this research are to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE desulfurization process reported by the MWOPC and to verify the forms-of-sulfur determination using the ASTM method for the PCE process evaluation.

Chou, M.I.M; Lytle, J.M.; Ruch, R.R.; Kruse, C.W.; Chaven, C.; Hackley, K.C.; Hughes, R.E.; Harvey, R.D.; Frost, J.K. [Illinois State Geological Survey, Champaign, IL (United States); Buchanan, D.H. [Eastern Illinois Univ., Charleston, IL (United States); Stucki, J.W. [Illinois Univ., Urbana, IL (United States); Huffman, G.; Huggins, F.E. [Kentucky Univ., Lexington, KY (United States)

1992-09-01

22

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. Annual report, September 1, 1991--August 31, 1992  

SciTech Connect

The Midwest Ore Processing Co. (MWOPC) has reported a precombustion coal desulfurization process using perchloroethylene (PCE) at 120{degree}C to remove up to 70% of the organic sulfur. However, this process has not been proven to be as successful with Illinois coals as it has been for Ohio and Indiana coals. Also, the high levels of organic sulfur removals observed by the MWOPC may be due to certain errors involved in interpreting data from the American Society For Testing and Materials (ASTM) method for forms-of-sulfur analysis. The purposes of this research are to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE desulfurization process and to verify the forms-of-sulfur determination using the ASTM method for evaluation of the PCE process. One problem that limits commercial application of the PCE process is the high chlorine content in the PCE-treated coals. Hence, an additional goal of this investigation is to develop a dechlorination procedure to remove excess PCE from the PCE-treated coal. MWOPC`s results have been repeated on our tests for the fresh IBC-104 coal. Oxidation of coals was found to affect subsequent PCE desulfurization. Elemental sulfur is more amenable than organic sulfur to removal by PCE. Ohio 5/6 coal appears to produce elemental sulfur more readily than Illinois coal during oxidation.

Chou, M.I.M.; Lytle, J.M.; Ruch, R.R.; Kruse, C.W.; Chaven, C.; Hackley, K.C.; Hughes, R.E.; Harvey, R.D.; Frost, J.K. [Illinois Dept. of Energy and Natural Resources, Springfield, IL (United States). Geological Survey; Buchanan, D.H. [Eastern Illinois Univ., Charleston, IL (United States); Stucki, J.W. [Illinois Univ., Urbana, IL (United States); Huffman, G.P.; Huggins, F.E. [Kentucky Univ., Lexington, KY (United States); Banerjee, D.D. [Center for Research on Sulfur in Coal, Carterville, IL (United States)

1992-12-31

23

Comparison between acetate and hydrogen as electron donors and implications for the reductive dehalogenation of PCE and TCE  

NASA Astrophysics Data System (ADS)

Bioremediation by reductive dehalogenation of groundwater contaminated with tetrachloroethene (PCE) or trichloroethene (TCE) is generally carried out through the addition of a fermentable electron donor such as lactate, benzoate, carbohydrates or vegetable oil. These fermentable donors are converted by fermenting organisms into acetate and hydrogen, either of which might be used by dehalogenating microorganisms. Comparisons were made between H2 and acetate on the rate and extent of reductive dehalogenation of PCE. PCE dehalogenation with H2 alone was complete to ethene, but with acetate alone it generally proceeded only about half as fast and only to cis-1,2-dichloroethene (cDCE). Additionally, acetate was not used as an electron donor in the presence of H2. These findings suggest the fermentable electron donor requirement for PCE dehalogenation to ethene can be reduced up to 50% by separating PCE dehalogenation into two stages, the first of which uses acetate for the conversion of PCE to cDCE, and the second uses H2 for the conversion of cDCE to ethene. This can be implemented with a recycle system in which the fermentable substrate is added down-gradient, where the hydrogen being produced by fermentation effects cDCE conversion into ethene. The acetate produced is recycled up-gradient to achieve PCE conversion into cDCE. With the lower electron donor usage required, potential problems of aquifer clogging, excess methane production, and high groundwater chemical oxygen demand (COD) can be greatly reduced.

Lee, Il-Su; Bae, Jae-Ho; McCarty, Perry L.

2007-10-01

24

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. Technical report, September 1, 1991--November 30, 1991  

SciTech Connect

A pre-combustion coal desulfurization process at 120{degree}C using perchloroethylene (PCE) to remove up to 70% of the organic sulfur has been developed by the Midwest Ore Processing Co. (MWOPC). However, this process has not yet proven to be as successful with Illinois coals as it has for Ohio and Indiana coals. The organic sulfur removal has been achieved only with highly oxidized Illinois coals containing high sulfatic sulfur. A logical explanation for this observation is vital to successful process optimization for the use of Illinois coals. In addition, the high levels of organic sulfur removals observed by the MWOPC may be due to certain errors involved in the ASTM data interpretation; this needs verification. For example, elemental sulfur extracted by the PCE may be derived from pyrite oxidation during coal pre-oxidation, but it may be interpreted as organic sulfur removed by the PCE using ASTM analysis. The goals of this research are: (1) to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE desulfurization process reported by the MWOPC, (2) to verify the forms-of-sulfur determination using the ASTM method for the PCE process evaluation, and (3) to determine the suitability of Illinois coals for use in the PCE desulfurization process. This project involves the Illinois State Geological Survey (ISGS), Eastern Illinois University (EIU), the University of Illinois-Urbana/Champaign (UI-UC), and the University of Kentucky, Lexington (UK). This is the first year of a two-year project.

Chou, M.I.M.

1991-12-31

25

Room-temperature chemisorption and thermal evolution of perchloroethylene and trichloroethylene on Si(1 1 1)7 × 7: Formation of chlorinated vinylene and vinylidene and acetylide adspecies, and thermal etching reactions  

Microsoft Academic Search

The prominent surface species and their corresponding bonding structures of perchloroethylene (PCE, C2Cl4) and trichloroethylene (TCE, C2HCl3) upon room-temperature adsorption and thermal excitation on Si(111)7×7 have been examined by vibrational electron energy loss spectroscopy (EELS) and thermal desorption spectrometry (TDS). The presence of the Si–Cl stretch at 510cm?1 shows that both PCE and TCE undergo dechlorination on Si(111)7×7, while the

Zhenhua He; K. T. Leung

2005-01-01

26

Photochemical Reactivity of Perchloroethylene.  

National Technical Information Service (NTIS)

Perchloroethylene (PCE), a solvent used in dry cleaning, has been suspected of contributing significantly to photochemical ozone/oxidant (O3/Ox) problems in urban atmospheres. Past evidence, however, was neither complete nor consistent. To interpret more ...

B. Dimitriades B. W. Gay R. R. Arnts R. L. Seila

1983-01-01

27

Photooxidation and biotrickling filtration for controlling industrial emissions of trichloroethylene and perchloroethylene  

Microsoft Academic Search

A two-stage process integrating ultraviolet oxidation and biotrickling filtration (UV–BTF) was developed for treatment of industrial air streams contaminated with trichloroethylene (TCE) and perchloroethylene (PCE). Laboratory-scale studies demonstrated that the UV–BTF system consistently achieved contaminant removal efficiencies of 99–100% under optimal conditions. The UV–BTF process employs an advanced oxidation process (AOP) such as UV photooxidation as pretreatment for alleviating biological

Walter Den; Varadarajan Ravindran; Massoud Pirbazari

2006-01-01

28

Determination of dichloromethane, trichloroethylene and perchloroethylene in urine samples by headspace solid phase microextraction gas chromatography–mass spectrometry  

Microsoft Academic Search

A method for the determination of volatile chlorinated hydrocarbons, namely dichloromethane (DCM), trichloroethylene (TCE), and perchloroethylene (PCE), in urine samples was developed using headspace solid phase microextraction (HS-SPME) gas chromatography–mass spectrometry (GC–MS). HS-SPME was performed using a 75?m Carboxen-polydimethylsiloxane fiber. Factors, which affect the HS-SPME process, such as adsorption and desorption times, stirring, salting-out effect, and temperature of sampling have

Diana Poli; Paola Manini; Roberta Andreoli; Innocente Franchini; Antonio Mutti

2005-01-01

29

PHOTOCHEMICAL REACTIVITY OF PERCHLOROETHYLENE  

EPA Science Inventory

Perchloroethylene (PCE), a solvent used in dry cleaning, has been suspected of contributing significantly to photochemical ozone/oxidant (O3/Ox) problems in urban atmospheres. Past evidence, however, was neither complete nor consistent. To interpret more conclusively the past evi...

30

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. Technical report, December 1, 1992--February 28, 1993  

SciTech Connect

The purpose of this project are to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE process developed by the Midwest Ore Processing Co.(MWOPC), to verify the forms-of-sulfur determination using the ASTM method for evaluation of the PCE process, and to develop a dechlorination procedure to remove excess PCE from the PCE-treated coal. The objectives for year-2 study are to verify the possible effect of PCE treatment on coal-derived FeS{sub 2}, FeSO{sub 4}, and Fe{sub 2}(SO{sub 4}){sub 3} on ASTM coal analysis, to investigate the behavior of sulfur during oxidation and PCE desulfurization using the isotopically signatured coal sample to investigate the proprietary reagent on the oxidation of the organic sulfur model compounds with and without additives, to evaluate this new oxidation on the organic sulfur removal by PCE desulfurization, and to study other innovative pretreatment processes for the removal of organic sulfur from coal under mild conditions. Oxidation study on the organosulfur model compounds alone was completed in first quarter. The oxidation reactions were repeated on the organosulfur model compounds with the presence of hydrocarbon additives. These additives are known to easily produce hydroperoxides during air oxidation. Analysis of the reaction products is in progress.

Chou, M.I.M.; Lytle, J.M.; Ruch, R.R.; Kruse, C.W.; Chaven, C.; Hackley, K.C.; Hughes, R.E.; Harvey, R.D. [Illinois Dept. of Energy and Natural Resources, Springfield, IL (United States). Geological Survey; Buchanan, D.H. [Eastern Illinois Univ., Charleston, IL (United States); Stucki, J.W. [Illinois Univ., Urbana, IL (United States); Huffman, G.; Huggins, F.E. [Kentucky Univ., Lexington, KY (United States); Ho, K.K. [Institute of Gas Technology, Chicago, IL (United States)

1993-05-01

31

Sulfur removal from high-sulfur Illinois coal by low-temperature perchloroethylene (PCE) extraction. [Quarterly] technical report, March 1, 1993--May 31, 1993  

SciTech Connect

The purposes of this project are: to independently confirm and possibly to improve the organic sulfur removal from Illinois coals with the PCE process developed by the Midwest Ore Processing Co. (MWOPC), to verify the forms-of-sulfur determination using the ASTM method for evaluation of the PCE process, and to develop a dechlorination procedure to remove excess PCE from the PCE-treated coal. The objectives for the second year are: to verify the possible effects of PCE treatment on coal-derived FeS{sub 2}, FeSO{sub 4}, and Fe{sub 2}(SO{sub 4}){sub 3} on ASTM coal analysis, to investigate the behavior of sulfur during oxidation and PCE desulfurization using the isotopically signatured coal sample, to investigate the effects of conditions and/or reagents on the oxidation of the organic-sulfur-model compounds, to evaluate the extended oxidation condition on the organic sulfur removal by PCE desulfurization, and to study other innovative pretreatment processes for the removal of organic sulfur from coal under mild conditions.

Chou, M.I.M. [Illinois State Geological Survey, Champaign, IL (United States); Buchanan, D.H. [Eastern Illinois Univ., Charleston, IL (United States); Stucki, J.W. [Illinois Univ., Urbana, IL (United States)

1993-09-01

32

Transition Metal Catalyst Assisted Reductive Dechlorination of Perchloroethylene by Anaerobic Aquifer Enrichments  

SciTech Connect

Bioremediation of groundwater contaminated with chlorinated solvents, such as perchloroethylene (PCE) or carbon tetrachloride, can be accomplished by adding nutrients to stimulate a microbial community capable of reductive dechlorination. However, biotransformation of these solvents, especially PCE, typically occurs very slowly or not at all. Experiments were conducted to evaluate whether the addition of transition metal tetrapyrrole catalysts would increase the reductive transformation of PCE to trichloroethylene (TCE) by sulfate-reducing enrichment cultures. Batch assays were used to test vitamin B12 and two synthetic sulfonatophenyl porphine catalysts for the stimulation of reductive dechlorination of PCE by sulfate-reducing bacteria (SRB) enriched from aquifer sediments from two locations at Dover Air Force Base. Cells from the enrichments were concentrated and added to batch assay vials. Vials containing SRB cells amended with vitamin B12 exhibited enhanced transformation of PCE to TCE compared with reactors amended with either synthetic catalysts or reactors containing cells alone. Methane production was observed in reactors that exhibited maximum levels of dechlorination. Storage of aquifer sediments between enrichments led to decreased levels of PCE dechlorination in subsequent assays.

Lee, Brady Douglas; Schaller, Kastli Dianne; Apel, William Arnold; Watwood, Maribeth E.

2000-04-01

33

Optic Neuritis with Residual Tunnel Vision in Perchloroethylene Toxicity  

Microsoft Academic Search

Trichloroethylene and perchloroethylene (PCE) are the major constituents of commercially available solutions used in dry cleaning shops. We describe the appearance of severe bilateral optic neuritis (ON) with unexpectedly high levels of PCE metabolites in blood and chloroform in urine in a 57-year-old woman owner of a small dry cleaning shop where she worked for about 20 years using PCE.

Marco Onofrj; Astrid Thomas; Cristina Paci; Giordano D’Andreamatteo; Lucia Toma; Domenico Rotilio

1999-01-01

34

Bayesian Analysis of a Physiologically Based Pharmacokinetic Model for Perchloroethylene in Humans  

Microsoft Academic Search

Perchloroethylene (PCE) is a widely distributed pollutant in the environment, and is the primary chemical used in dry cleaning. PCE-induced liver cancer was observed in mice, and central nervous system (CNS) effects were reported in dry-cleaning workers. To support reconstruction of human PCE exposures, including the potential for CNS effects, an existing physiologically based pharmacokinetic (PBPK) model for PCE in

Junshan Qiu; Yeh-Chung Chien; James V. Bruckner; Jeffery W. Fisher

2009-01-01

35

Cancer in relation to occupational exposure to perchloroethylene  

Microsoft Academic Search

Exposure to perchloroethylene (PCE) occurs in a number of occupational settings in which organic solvents are used, and, in particular, is widely prevalent in the dry-cleaning industry. This review summarizes the results of studies of the occurrence of the individual types of cancer in dry cleaners. Two of those cancers of greatest a priori concern (because of results in PCE-exposed

Noel S. Weiss

1995-01-01

36

[Assessment of exposure to perchloroethylene in dry-cleaning shops].  

PubMed

The occupational work-risk by PCE was evaluated in a group of 143 workers in 47 laundries, where perchloroethylene (PCE) was the only solvent used. Airborne measurements of PCE showed mean concentration values below the TLV-TWA, and a number of instant concentration values superior to TLV-STEL. Trichloracetic acid (TCA) values in the urine of exposed workers was superior to the limit established by our institute (29% of workers). PMID:3154908

Missere, M; Giacomini, C; Gennari, P; Violante, F; Dallolio, L; Failla, G; Lodi, V; Raffi, G

1988-11-01

37

PBPK Modeling of the Percutaneous Absorption of Perchloroethylene from a Soil Matrix in Rats and Humans  

Microsoft Academic Search

Perchloroethylene (PCE) is a widely used volatile organic chemi- cal. Exposures to PCE are primarily through inhalation and dermal contact. The dermal absorption of PCE from a soil matrix was compared in rats and humans using real-time MS\\/MS exhaled breath technology and physiologically based pharmacokinetic (PBPK) mod- eling. Studies with rats were performed to compare the effects of loading volume,

Torka S. Poet; Karl K. Weitz; Richard A. Gies; Jeffrey A. Edwards; Karla D. Thrall; Richard A. Corley; Hanafi Tanojo; Xiaoying Hui; Howard I. Maibach; Ronald C. Wester

2002-01-01

38

Worker Exposure to Perchloroethylene in the Commercial Dry Cleaning Industry  

Microsoft Academic Search

The National Institute for Occupational Safety and Health (NIOSH) conducted industrial hygiene surveys at 44 commercial dry cleaning facilities in five states as part of an industrywide study to assess the health effects of long-term, low-level exposures to perchloroethylene (PCE). Time-weighted average (TWA) and peak exposures to PCE were determined by collecting personal air samples using activated charcoal tubes and

HOWARD R. LUDWIG; MICHAEL V. MEISTER; DENNIS R. ROBERTS; CLINTON COX

1983-01-01

39

Optimization of Simultaneous Chemical and Biological Mineralization of Perchloroethylene†  

PubMed Central

Optimization of the simultaneous chemical and biological mineralization of perchloroethylene (PCE) by modified Fenton’s reagent and Xanthobacter flavus was investigated by using a central composite rotatable experimental design. Concentrations of PCE, hydrogen peroxide, and ferrous iron and the microbial cell number were set as variables. Percent mineralization of PCE to CO2 was investigated as a response. A second-order, quadratic response surface model was generated and fit the data adequately, with a correlation coefficient of 0.72. Analysis of the results showed that the PCE concentration had no significant effect within the tested boundaries of the model, while the other variables, hydrogen peroxide and iron concentrations and cell number, were significant at ? = 0.05 for the mineralization of PCE. The 14C radiotracer studies showed that the simultaneous chemical and biological reactions increased the extent of mineralization of PCE by more than 10% over stand-alone Fenton reactions.

Buyuksonmez, Fatih; Hess, Thomas F.; Crawford, Ronald L.; Paszczynski, Andrzej; Watts, Richard J.

1999-01-01

40

Industrial Hygiene Report: Perchloroethylene at Dubarry Cleaners, Detroit, Michigan,  

National Technical Information Service (NTIS)

An on site visit was made to Dubarry Cleaners, Detroit, Michigan, as part of an industrywide mortality and industrial hygiene study of dry cleaning workers exposed to perchloroethylene (127184) (PCE). Air samples were taken at the facility and the time we...

D. R. Roberts

1980-01-01

41

PHASE BEHAVIOR OF WATER/PERCHLOROETHYLENE/ANIONIC SURFACTANT SYSTEMS  

EPA Science Inventory

Winsor Type I (o/w), Type II (w/o), and Type III (middle phase) microemulsions have been generated for water and perchloroethylene (PCE) in combination with anionic surfactants and the appropriate electrolyte concentration. The surfactant formulation was a combination of sodium d...

42

USE OF A PHYSIOLOGICALLY BASED MODEL TO PREDICT SYSTEMIC UPTAKE AND RESPIRATORY ELIMINATION OF PERCHLOROETHYLENE  

EPA Science Inventory

The pharmacokinetics of inhaled perchloroethylene (PCE) were studied in male Sprague-Dawley rats to characterize pulmonary absorption and elimination. irect measurements of the time-course of PCE in the blood and breath were used to evaluate the ability of a physiologically-based...

43

A mass balance study of the phytoremediation of perchloroethylene-contaminated groundwater  

PubMed Central

A mass balance study was performed under controlled field conditions to investigate the phytoremediation of perchloroethylene (PCE) by hybrid poplar trees. Water containing 7–14 mg L?1 PCE was added to the test bed. Perchloroethylene, trichloroethylene, and cis-dichloroethylene were detected in the effluent at an average of 0.12 mg L?1, 3.9 mg L?1, and 1.9 mg L?1, respectively. The total mass of chlorinated ethenes in the water was reduced by 99%. Over 95% of the recovered chlorine was as free chloride in the soil, indicating near-complete dehalogenation of the PCE. Transpiration, volatilization, and accumulation in the trees were all found to be minor loss mechanisms. In contrast, 98% of PCE applied to an unplanted soil chamber was recovered as PCE in the effluent water or volatilized into the air. These results suggest that phytoremediation can be an effective method for treating PCE-contaminated groundwater in field applications.

James, C. Andrew; Xin, Gang; Doty, Sharon L.; Muiznieks, Indulis; Newman, Lee; Strand, Stuart E.

2010-01-01

44

Photolytic and photocatalytic oxidation of perchloroethylene in air  

NASA Astrophysics Data System (ADS)

The perchloroethylene (PCE) photolytic and photocatalytic oxidation reactions took place simultaneously when the UVC light and TiO2 catalyst were used. Each of these two processes was studied separately in this work. The photolytic oxidation of PCE was performed using UVC light without TiO2 under different reaction conditions including temperature, humidity, reactor diameter, PCE inlet concentration, and space time. It was found that the PCE photolytic oxidation process followed the second-order reaction model. Both the chlorine free radical induced chain reaction and the non-chain reaction were proposed to explain the PCE degradation and by- products. The reactor wall played an important role in quenching the photolytic oxidation reaction. The PCE conversion increased to a maximum when the diameter of the reactor decreased to 35-mm, and then decreased after that. This phenomenon could be due to a wall quenching effect. The PCE conversion decreased when temperature increased. This was caused by a decrease of UVC light intensity and significant wall effect at high temperature. The PCE conversion was found to be independent from humidity condition. This indicated that the water molecule was not involved in the PCE photolytic oxidation reaction. The PCE photocatalytic oxidation reaction was performed using UVA light with TiO2 catalyst under various factors: humidity, temperature, space time, PCE inlet concentration, and light intensity. This was done to examine their effect on PCE conversion. The PCE conversion decreased as the humidity or temperature increased. The temperature effect could be caused by the decrease of UVA light intensity and desorption of PCE molecules from the catalyst surface at high temperature. The PCE inlet concentration effect showed the PCE photocatalytic oxidation followed the Langmuir- Hinshelwood model. The light intensity had a positive effect on PCE conversion. The effect of TiO2 catalyst distribution on PCE conversion was also studied. A well-distributed TiO2 catalyst could reach a higher PCE conversion than the poor-distributed TiO2 catalyst under the same reaction condition. Based on free radical formation, a mechanism of the photocatalytic oxidation was proposed to explain the product distribution. The associated reactions of PCE photolytic and photocatalytic oxidation were conducted under the condition of UVC irradiating on the TiO2 catalyst. The well-distributed TiO2, UVC input power, and optic fibers could significantly increase the PCE degradation efficiency. On the contrary, the aluminum screen, pellets, and Lucite baffles decreased the PCE degradation efficiency, which could be due to the blockage of UVC light.

Liu, Yun-Chieh

2000-11-01

45

Experimental Assessment of Bioenhanced Dissolution and Microbial Distribution During PCE-NAPL Source Zone Bioremediation  

Microsoft Academic Search

Specialized anaerobic bacteria are capable of detoxifying tetrachloroethene (PCE) and trichloroethene (TCE) as well as enhancing contaminant dissolution from dense nonaqueous phase liquid (DNAPL) source zones. Thus, the microbial reductive dechlorination process has emerged as a promising remedial technology for PCE- and TCE-DNAPL source zones. However, the effects of microbial activity and distribution within DNAPL source zones on dissolution enhancement

B. K. Amos; E. J. Suchomel; K. D. Pennell; F. E. Loeffler

2006-01-01

46

Solubilization and mobilization of perchloroethylene by cosolvents in porous media  

SciTech Connect

Batch equilibrium studies conducted for perchloroethylene (PCE)/cosolvent systems determined that the log-linear solubility relationship is not a completely accurate method to predict solubility of PCE in cosolvent mixtures over an entire range of volume fractions. Batch studies resulted in cosolvency powers of 3.73 and 4.13 for ethanol and isopropanol, respectively. However, log-linear predictions may be adequate for estimations necessary for remediation efforts. The use of the Extended Hildebrand model is recommended. The interfacial tension (IFT) resulting from cosolvent mixtures when compared to the initial volume fraction of cosolvent showed a relationship, similar to the log-linear model. An ``IFT reduction power`` was determined for ethanol to be {minus}3.60, and isopropyl alcohol, {minus}5.80, describing the ability of cosolvents to reduce IFT with increasing volume fraction. IFT values are accurately estimated by PCE solubility in regimes conducive to cosolvent flushing.

Van Valkenburg, M.E.

1999-07-28

47

DEVELOPMENT OF A PHYSIOLOGICALLY BASED PHARMACOKINETIC MODEL FOR PERCHLOROETHYLENE USING TISSUE CONCENTRATION-TIME DATA  

EPA Science Inventory

The tissue disposition of perchloroethylene (PCE) was characterized experimentally in rats in order to: 1) btain input parameters from in vivo data for the development of a physiologically-based pharmacokinetic (PBPK) model; and 2) use the PBPK model to predict the deposition of ...

48

Industrial Hygiene Report, Perchloroethylene at Key Club Cleaners, Skokie, Illinois, July 18, 1979.  

National Technical Information Service (NTIS)

An on site visit was made to the Key Club Cleaners (SIC-7216) located in Skokie, Illinois as part of an industrywide mortality and industrial hygiene study of the exposure of dry cleaning workers to perchloroethylene (127184) (PCE). Current exposure level...

D. R. Roberts

1980-01-01

49

WASHABILITY CURVES FOR PYRITE REMOVAL IN COAL USING PERCHLOROETHYLENE AS HEAVY MEDIUM  

Microsoft Academic Search

Pyritic sulfur is removed from raw, high sulfur coal by gravitational separation using a suitable solvent, or heavy medium. This is possible due to the inherent difference in the specific gravity of clean coal and the mineral matter in it. The effectiveness of perchloroethylene (PCE) as a heavy medium was experimentally evaluated. The most important factors governing the efficiency of

Padmakar Vishnubhatt; Sunggyu Lee

1993-01-01

50

Infiltration and redistribution of perchloroethylene in partially saturated, stratified porous media 1 Contribution from the Alabama Agric. Exp. Stn., Auburn University, AL, USA. 1  

Microsoft Academic Search

Contamination of the subsurface by nonaqueous phase liquids (NAPLs) is a widespread problem. To investigate the behavior of a nonspreading, dense NAPL (DNAPL) in the vadose zone, we conducted perchloroethylene (PCE) infiltration experiments in nominally 1- and 2-dimensional (D), stratified porous media. In addition, the usefulness and limitations of a multifluid flow simulator to describe PCE infiltration and redistribution under

C. Hofstee; Mart Oostrom; J. H Dane; R. C Walker

1998-01-01

51

Cytotoxicity of trichloroethylene and perchloroethylene on normal human epidermal keratinocytes and protective role of Vitamin E  

Microsoft Academic Search

Trichloroethylene (TCE) and perchloroethylene (PERC), the most common alkenyl halides, have been extensively used in industry, and can cause skin damage. To evaluate their cytotoxic potential on skin, the effects of these agents on the normal human epidermal keratinocytes (NHEK) were investigated. Their action on cell viability, membrane integrity and lipid peroxidation (LPO) was assessed by neutral red uptake (NRU)

Qi-Xing Zhu; Tong Shen; Rui Ding; Zhao-Zhao Liang; Xue-Jun Zhang

2005-01-01

52

Cytogenetic analysis of an exposed-referent study: perchloroethylene-exposed dry cleaners compared to unexposed laundry workers  

PubMed Central

Background Significant numbers of people are exposed to tetrachloroethylene (perchloroethylene, PCE) every year, including workers in the dry cleaning industry. Adverse health effects have been associated with PCE exposure. However, investigations of possible cumulative cytogenetic damage resulting from PCE exposure are lacking. Methods Eighteen dry cleaning workers and 18 laundry workers (unexposed controls) provided a peripheral blood sample for cytogenetic analysis by whole chromosome painting. Pre-shift exhaled air on these same participants was collected and analyzed for PCE levels. The laundry workers were matched to the dry cleaners on race, age, and smoking status. The relationships between levels of cytological damage and exposures (including PCE levels in the shop and in workers' blood, packyears, cumulative alcohol consumption, and age) were compared with correlation coefficients and t-tests. Multiple linear regressions considered blood PCE, packyears, alcohol, and age. Results There were no significant differences between the PCE-exposed dry cleaners and the laundry workers for chromosome translocation frequencies, but PCE levels were significantly correlated with percentage of cells with acentric fragments (R2 = 0.488, p < 0.026). Conclusions There does not appear to be a strong effect in these dry cleaning workers of PCE exposure on persistent chromosome damage as measured by translocations. However, the correlation between frequencies of acentric fragments and PCE exposure level suggests that recent exposures to PCE may induce transient genetic damage. More heavily exposed participants and a larger sample size will be needed to determine whether PCE exposure induces significant levels of persistent chromosome damage.

2011-01-01

53

Cometabolic degradation of TCE and DCE without intermediate toxicity  

SciTech Connect

Trichloroethylene (TCE) and cis-1,2-dichloroethylene (DCE) cometabolic degradation by a filamentous, phenol-oxidizing enrichment from a surface-water source were investigated in batch tests. No intermediate toxicity effects were evident during TCE or DCE degradation for loadings up to 0.5 mg TCE/mg VSS or 0.26 mg DCE/mg VSS. Phenol addition up to 40 mg/L did not inhibit TCE or DCE degradation. TCE specific degradation rates ranged from 0.28 to 0.51 g TCE/g VSS-d with phenol present, versus an average endogenous rate of 0.18 g TCE/g VSS-d. DCE specific degradation rates ranged from 0.79 to 2.92 g DCE/g VSS-d with phenol present, versus 0.27 to 1.5 g DCE/g VSS-d for endogenous conditions. There was no inhibition of DCE degradation rates at concentrations as high as 83 mg/L. TCE degradation rates declined between 40 and 130 mg/L TCE. Perchloroethylene, 1,1,1-trichloroethane, and chloroform were not degraded.

Bielefeldt, A.R.; Stensel, H.D.; Strand, S.E. [Univ. of Washington, Seattle, WA (United States)

1995-11-01

54

Cytogenetic analysis of an exposed-referent study: perchloroethylene-exposed dry cleaners compared to unexposed laundry workers  

Microsoft Academic Search

Background  Significant numbers of people are exposed to tetrachloroethylene (perchloroethylene, PCE) every year, including workers in\\u000a the dry cleaning industry. Adverse health effects have been associated with PCE exposure. However, investigations of possible\\u000a cumulative cytogenetic damage resulting from PCE exposure are lacking.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Eighteen dry cleaning workers and 18 laundry workers (unexposed controls) provided a peripheral blood sample for cytogenetic\\u000a analysis by

James D Tucker; Karen J Sorensen; Avima M Ruder; Lauralynn Taylor McKernan; Christy L Forrester; Mary Ann Butler

2011-01-01

55

Electrochemical degradation of perchloroethylene in aqueous media: an approach to different strategies.  

PubMed

An approaching study to the electrochemical degradation of perchloroethylene (PCE) in water has been carried out using controlled current density degradation electrolyses. The different electrochemical strategies to degrade perchloroethylene in aqueous media (i.e. cathodic, anodic and dual treatments) have been checked using divided and undivided configurations. The influence of the initial concentration, pH and current density on the general behavior of the system has been studied, and special attention was paid to the nature of the byproducts formed and to the analysis of the closed mass balance at the end of the reaction. Results from several analytical techniques have been compared. Undivided configuration provides the best results in these experimental conditions, with degradation percentages higher than 50% and with only 6% of the initial perchloroethylene concentration remaining in the system. PMID:19303130

Sáez, Verónica; Esclapez Vicente, M D; Frías-Ferrer, Angel J; Bonete, Pedro; González-García, José

2009-02-25

56

Analysis of Natural Attenuation at the Park-Euclid PCE Contaminated Site  

NASA Astrophysics Data System (ADS)

Tetrachloroethe (PCE) and diesel contamination has been documented in the local perched and regional aquifers at the Park-Euclid WQARF site in Tucson, AZ. Monitored natural attenuation (MNA) is currently been evaluated as a potential remediation technology for the PCE contamination at the site. Physicochemical characterization of the immiscible liquid contamination has been conducted in prior studies. The focus of this study is to evaluate the biochemical processes active at the site. Analysis of the Arizona Department of Environmental Quality (ADEQ) database shows that the original contamination in the perched aquifer, where PCE was the single chlorinated ethene involved, has evolved into a mixture containing PCE and several transformation compounds typically associated with PCE (Trichloroethene, TCE, Dichloroethene, DCE, and Vinylchloride, VC). In general terms, PCE concentrations have decreased while TCE concentrations have been constant in time. Accumulation of DCE isomers (mainly cis-1,2-DCE) is observed in most of the wells. Conversely, VC has been observed in only three wells and only since 2001. This suggests that PCE is undergoing transformation and that DCE transformation is the limiting step in the mineralization of PCE. The regional aquifer does not show evidence of active PCE transformation processes.

Carreon, C.; Brusseau, M. L.; Zhang, Z.; Field, J.

2004-12-01

57

EMISSIONS OF PERCHLOROETHYLENE FROM DRY CLEANED FABRICS  

EPA Science Inventory

The paper gives results of an evaluation of emissions of perchloroethylene (tetrachloroethylene) from dry cleaned fabrics to determine: how introducing fresh dry cleaning into a home affects the indoor concentration of perchloroethylene, and the effectiveness of "airing out" dry ...

58

Possible involvement of glutathione and p53 in trichloroethylene- and perchloroethylene-induced lipid peroxidation and apoptosis in human lung cancer cells  

Microsoft Academic Search

Trichloroethylene (TCE) and perchloroethylene (PERC) are volatile organic compounds (VOCs) that are primarily inhaled through the respiratory system. The aim of this study was to elucidate the role of glutathione (GSH) and p53 in TCE- and PERC-induced lung toxicity. Human lung adenocarcinoma cells NCI-H460 (p53-wild-type) have constitutively lower levels of GSH than NCI-H1299 (p53-null) cells. The results showed that exposure

Shiang-Jiuun Chen; Jia-Lin Wang; Jian-Hung Chen; Rong-Nan Huang

2002-01-01

59

Experimental Assessment of Bioenhanced Dissolution and Microbial Distribution During PCE-NAPL Source Zone Bioremediation  

NASA Astrophysics Data System (ADS)

Specialized anaerobic bacteria are capable of detoxifying tetrachloroethene (PCE) and trichloroethene (TCE) as well as enhancing contaminant dissolution from dense nonaqueous phase liquid (DNAPL) source zones. Thus, the microbial reductive dechlorination process has emerged as a promising remedial technology for PCE- and TCE-DNAPL source zones. However, the effects of microbial activity and distribution within DNAPL source zones on dissolution enhancement remain poorly understood. Experiments to evaluate the activity and distribution of dechlorinating populations in the immediate vicinity of a PCE-NAPL source zone were performed in a one-dimensional soil column containing a 10 cm NAPL (0.25 mol/mol PCE in hexadecane) source zone and a 50 cm down-gradient plume region. In one column experiment, Sulfurospirillum multivorans, a PCE-to-cis-DCE dechlorinating isolate, transformed PCE to cis-DCE with an approximate 4-fold cumulative dissolution enhancement. Quantitative real-time PCR (qPCR) correlated activity and distribution of S. multivorans with enhanced PCE dissolution. Similar NAPL dissolution enhancement was observed in another column augmented with a PCE-to-ethene dechlorinating consortium containing Dehalococcoides, Dehalobacter, and Geobacter populations, with PCE dechlorinated primarily to cis-DCE and vinyl chloride. Geobacter and Dehalococcoides populations were detected within the source zone, and increases in the dechlorinator population sizes coincided spatially with increased formation of dechlorination products. Experimental results indicate that mass transfer enhancement by microbial reductive dechlorination within NAPL source zones is possible, and that the distribution of relevant microbial populations directly affects dissolution enhancement. Ongoing work focuses on evaluating the distribution of specific Dehalococcoides strains in the vicinity of PCE-NAPL.

Amos, B. K.; Suchomel, E. J.; Pennell, K. D.; Loeffler, F. E.

2006-12-01

60

40 CFR 63.471 - Facility-wide standards.  

Code of Federal Regulations, 2010 CFR

...perchloroethylene (PCE), trichloroethylene (TCE) and methylene chloride (MC) used at...facilities PCE only a 4,800 8,000 TCE only 14,100 23,500 MC only 60...equation, the facility emissions of PCE and TCE are weighted according to their...

2009-07-01

61

40 CFR 63.471 - Facility-wide standards.  

Code of Federal Regulations, 2010 CFR

...perchloroethylene (PCE), trichloroethylene (TCE) and methylene chloride (MC) used at...facilities PCE only a 4,800 8,000 TCE only 14,100 23,500 MC only 60...equation, the facility emissions of PCE and TCE are weighted according to their...

2010-07-01

62

EMISSIONS OF PERCHLOROETHYLENE FROM DRY CLEANED FABRICS  

EPA Science Inventory

A study was conducted to evaluate the emissions of perchloroethylene (tetrachloroethylene) from dry cleaned fabrics to determine: (a) how the introduction of fresh dry cleaning into a home affects the indoor concentration of perchloroethylene, and (b) the effectiveness of â??airing...

63

Factors controlling the carbon isotope fractionation of tetra- and trichloroethene during reductive dechlorination by Sulfurospirillum ssp. and Desulfitobacterium sp. strain PCE-S.  

PubMed

Carbon stable isotope fractionation of tetrachloroethene (PCE) and trichloroethene (TCE) was investigated during reductive dechlorination. Growing cells of Sulfurospirillum multivorans, Sulfurospirillum halorespirans, or Desulfitobacterium sp. strain PCE-S, the respective crude extracts and the abiotic reaction with cyanocobalamin (vitamin B(12)) were used. Fractionation of TCE (alphaC=1.0132-1.0187) by S. multivorans was more than one order of magnitude higher than values previously observed for tetrachloroethene (PCE) (alphaC=1.00042-1.0017). Similar differences in fractionation were observed during reductive dehalogenation by the close relative S. halorespirans with alphaC=1.0046-1.032 and alphaC=1.0187-1.0229 for PCE and TCE respectively. TCE carbon isotope fractionation (alphaC=1.0150) by the purified PCE-reductive dehalogenase from S. multivorans was more than one order of magnitude higher than fractionation of PCE (alphaC=1.0017). Carbon isotope fractionation of TCE by Desulfitobacterium sp. strain PCE-S (alphaC=1.0109-1.0122) as well as during the abiotic reaction with cyanocobalamin (alphaC=1.0154) was in a similar range to previously reported values for fractionation by mixed microbial cultures. In contrast with previous results with PCE, no effects due to rate limitations, uptake or transport of the substrate to the reactive site could be observed during TCE dechlorination. Our results show that prior to a mechanistic interpretation of stable isotope fractionation factors it has to be carefully verified how other factors such as uptake or transport affect the isotope fractionation during degradation experiments with microbial cultures. PMID:17908097

Cichocka, Danuta; Siegert, Michael; Imfeld, Gwenaël; Andert, Janet; Beck, Kirsten; Diekert, Gabriele; Richnow, Hans-Hermann; Nijenhuis, Ivonne

2007-10-01

64

The use of Markov chain Monte Carlo uncertainty analysis to support a Public Health Goal for perchloroethylene.  

PubMed

The current Public Health Goal (PHG) for perchloroethylene (PCE) was derived using upper-bound estimates of fractional PCE metabolism in humans. These estimates were in part obtained from a published evaluation of the uncertainty and variability in human PCE metabolism conducted using a physiologically-based pharmacokinetic (PBPK) model in a Markov chain Monte Carlo (MCMC) analysis; however, the data used in that analysis were limited to post-exposure PCE blood and exhaled air concentrations from a single study. A more recent study [Volkel, W., Friedewald, M., Lederer, E., Pahler, A., Parker, J., Dekant, W., 1998. Biotransformation of perchloroethene: dose-dependent excretion of trichloroacetic acid, dichloroacetic acid, and N-acetyl-S-(trichlorovinyl)-l-cysteine in rats and humans after inhalation. Toxicol. Appl. Pharmacol. 153(1), 20-27.] provides data on blood concentrations of PCE and its major metabolite, trichloroacetic acid (TCA), and urinary excretion of TCA following exposure of human subjects to lower concentrations of PCE (10-40ppm) than in previous studies. In the present effort, a new MCMC analysis was performed that focused on data from this study along with two others [Fernandez, J., Guberan, E., Caperos, J., 1976. Experimental human exposures to tetrachloroethylene vapor and elimination in breath after inhalation. Am. Ind. Hyg. Assoc. J. 37, 143-150; Monster, A., Boersma, G., Steenweg, H., 1979. Kinetics of tetrachloroethylene in volunteers; influence of exposure concentration and work load. Int. Arch. Occup. Environ. Health 42, 303-309.] providing data on PCE blood concentrations and urinary excretion of TCA. To provide an accurate prediction of TCA kinetics, the PBPK model used here includes a description of the metabolism of PCE to TCA in both the liver and kidney. The resulting upper 95th percentile estimates of fraction of PCE metabolized by inhalation and oral routes were 2.1 and 5.2%, respectively, compared to 58 and 79% used in the derivation of the PHG. PMID:16901594

Covington, Tammie R; Robinan Gentry, P; Van Landingham, Cynthia B; Andersen, Melvin E; Kester, Janet E; Clewell, Harvey J

2006-08-09

65

Simulating Metabolic Reductive Decholorination with Multiple Cultures during Bioenhanced PCE-NAPL Dissolution  

Microsoft Academic Search

A recently conducted laboratory experiment investigating metabolic reductive dechlorination in dense non-aqueous phase liquid (DNAPL) source zones demonstrated enhanced DNAPL dissolution by increasing the driving force for mass transfer due to reductions in the aqueous phase. Tetrachloroethene (PCE) was degraded sequentially to cis-1,2-dichloroethene (cis-DCE) through trichloroethylene (TCE) and to ethene via vinyl chloride (VC) by Geobacter and Dehalococcoides, respectively. Significant

M. Chen; L. Abriola; J. Christ; B. K. Amos; E. J. Suchomel; K. D. Pennell; F. Loeffler

2009-01-01

66

HORIZONTAL LASAGNA TO BIOREMEDIATE TCE  

EPA Science Inventory

Removal of TCE from these tight clay soils has been technically difficult and expensive. However, the LASAGNATM technique allows movement of the TCE into treatment zones for biodegradation or dechlorination in place, lessening the costs and exposure to TCE. Electroosmosis was c...

67

MEASUREMENT OF PERCHLOROETHYLENE IN AMBIENT AIR  

EPA Science Inventory

Perchloroethylene (i.e., tetrachloroethylene) is an organic solvent widely used in dry cleaning and industrial metal degreasing operations. Short-term field studies were conducted in each of three major metropolitan areas which were selected on the basis of the number, density an...

68

NEUROTOXICITY OF TETRACHLOROETHYLENE (PERCHLOROETHYLENE): DISCUSSION PAPER  

EPA Science Inventory

This paper is a background document for a meeting of neurotoxicity experts to discuss the central nervous system effects of exposure to perchloroethylene (perc). The document reviews the literature on neurological testing of people exposed to perc occupationally in dry cleanin...

69

The Physiological Opportunism of Desulfitobacterium hafniense Strain TCE1 towards Organohalide Respiration with Tetrachloroethene  

PubMed Central

Desulfitobacterium hafniense strain TCE1 is capable of metabolically reducing tetra- and trichloroethenes by organohalide respiration. A previous study revealed that the pce gene cluster responsible for this process is located on an active composite transposon, Tn-Dha1. In the present work, we investigated the effects on the stability of the transposon during successive subcultivations of strain TCE1 in a medium depleted of tetrachloroethene. At the physiological level, an increased fitness of the population was observed after 9 successive transfers and was correlated with a decrease in the level of production of the PceA enzyme. The latter observation was a result of the gradual loss of the pce genes in the population of strain TCE1 and not of a regulation mechanism, as was postulated previously for a similar phenomenon described for Sulfurospirillum multivorans. A detailed molecular analysis of genetic rearrangements occurring around Tn-Dha1 showed two independent but concomitant events, namely, the transposition of the first insertion sequence, ISDha1-a, and homologous recombination across identical copies of ISDha1 flanking the transposon. A new model is proposed for the genetic heterogeneity around Tn-Dha1 in D. hafniense strain TCE1, along with some considerations for the cleavage mechanism mediated by the transposase TnpA1 encoded by ISDha1.

Duret, Aurelie; Holliger, Christof

2012-01-01

70

Using tree core samples to monitor natural attenuation and plume distribution after a PCE spill.  

PubMed

The potential of using tree core samples to detect and monitor natural attenuation of perchloroethene (PCE) in groundwater was investigated at a PCE-contaminated site. In the area of the known plume with PCE concentrations between 0.004 and > 40 mg/L, cores were collected from tree trunks at a height of about 1 m above ground surface. Tree sampling of the site was completed in under six hours. Chlorinated ethenes were analyzed by headspace GC/MS. PCE (0.001 to 7 mg/ kg) and natural attenuation products, TCE (< 0.001 to 0.4 mg/ kg) and c-DCE (< 0.001 to 0.46 mg/kg), were detected in tree cores. 1,1-dichloroethene and vinyl chloride were not detected, corresponding to very low concentrations in the groundwater. The contaminant plume was mapped from the concentrations measured in trees, which delineated a probable hot spot area that had been undetected in decades of traditional groundwater monitoring. Natural attenuation products in tree cores increased with distance from the known source area. Concentrations of PCE and reductive dechlorination products in tree cores were correlated with the corresponding groundwater concentrations. Within a range of limitations, tree-core sampling provides a rapid, reliable and inexpensive method to investigate the extent of shallow contamination by chlorinated ethenes in soil and groundwater. PMID:18441825

Larsen, Morten; Burken, Joel; Machackova, Jirina; Karlson, Ulrich Gosewinkel; Trappt, Stefan

2008-03-01

71

Effect of dechlorinating bacteria on the longevity and composition of PCE-containing nonaqueous phase liquids under equilibrium dissolution conditions  

SciTech Connect

The influence of dechlorinating microorganisms on PCE and its reduced end products in the presence of a PCE-containing nonaqueous phase liquid (NAPL) was investigated. Experiments were conducted in continuous-flow stirred-tank reactors (CFSTRs) containing a mixed PCE dechlorinating culture and a model NAPL consisting of PCE and tridecane. Comparisons between biotic and abiotic CFSTRs demonstrated that dechlorination resulted in a factor of 14 increase in PCE removal rates from the NAPL. The formation of dechlorination daughter products trichloroethene and cis-dichloroethene were observed, and cis-dichloroethene was not dechlorinated further. Partitioning of daughter products between phases caused temporal changes in the chlorinated ethenes distribution within the NAPL. The combined effects of dissolution and dechlorination on the removal of chlorinated ethenes from the NAPL were described using a mathematical model that approximated dechlorination as a pseudo-first-order process. Pseudo-first-order dechlorination rate coefficients for PCE and TCE were determined and were 0.18 and 0.27 h{sup {minus}1}, respectively. It was determined that total chlorinated ethenes removal from the NAPL would be achieved in 13 days in biotic CFSTRs, as compared to 77 days in the abiotic CFSTRs--corresponding to an 83% reduction in longevity of the chlorinated ethenes component of the NAPL.

Carr, C.S.; Garg, S.; Hughes, J.B.

2000-03-15

72

The PACSAT Communications Experiment (PCE)  

SciTech Connect

While VITA (Volunteers in Technical Assistance) is the recognized world leader in low earth orbiting (LEO) satellite technology (below 1 GHz), its involvement in communications technologies is to facilitate renewable energy technology transfer to developing countries. A communications payload was incorporated into the UoSat 2 satellite (Surrey Univ., UK), launched in 1984; a prototype satellite (PCE) was also launched Jan 1990. US DOE awarded a second grant to VITA to design and test the prototype ground stations (command and field), install field ground stations in several developing country sites, pursue the operational licensing process, and transfer the evaluation results to the design of an operating system. This report covers the principal tasks of this grant.

Not Available

1993-02-12

73

Trichloroethylene (TCE) adsorption using sustainable organic mulch.  

PubMed

Soluble substrates (electron donors) have been commonly injected into chlorinated solvent contaminated plume to stimulate reductive dechlorination. Recently, different types of organic mulches with economic advantages and sustainable benefits have received much attention as new supporting materials that can provide long term sources of electron donors for chlorinated solvent bioremediation in engineered biowall systems. However, sorption capacities of organic mulches for chlorinated solvents have not been studied yet. In this study, the physiochemical properties of organic mulches (pine, hardwood and cypress mulches) were measured and their adsorption capacity as a potential media was elucidated. Single, binary and quaternary isotherm tests were conducted with trichloroethylene (TCE), tetrachloroethylene (PCE), trans-dichloroethylene (trans-DCE) and cis-dichloroethylene (cis-DCE). Among the three tested mulches, pine mulch showed the highest sorption capacity for the majority of the tested chemicals in single isotherm test. In binary or quaternary isotherm tests, competition among chemicals appears to diminish the differences in Q(e) for tested mulches. However, pine mulch also showed higher adsorption capacity for most chemicals when compared to hardwood and cypress mulches in the two isotherm tests. Based upon physicochemical properties of the three mulches, higher sorption capacity of pine mulch over hardwood and cypress mulches appears to be attributed to a higher organic carbon content and the lower polarity. PMID:20605328

Wei, Zongsu; Seo, Youngwoo

2010-05-02

74

TCE treatment pasta-bilities.  

PubMed Central

Monsanto's "Lasagna" process uses layers of treatment zones spaced between buried electrodes to remove trichloroethylene (TCE) from contaminated soil and groundwater. TCE is used primarily as a metal degreaser as well as in products such as dyes, printing ink, and paint. TCE can eventually make its way into the environment and is prevalent in the water and soil of industrialized nations. Although TCE breaks down in a few days when released into the atmosphere, it degrades much more slowly in soil, taking months or years. Moreover, it is often broken down by microbes into toxic substances such as vinylidene chloride (a suspected human carcinogen) and vinyl chloride (a known human carcinogen). The Lasagna process is based on the principle of electro-osmosis, in which an electric current draws water from low--permeability soils such as clays, silts, and fine sands. To remove TCE from contaminated soils, Monsanto scientists added layers of filtering media, which attack the contaminant as it is pulled from electrode to electrode. The technology has been tested at the Paducah Gaseous Diffusion Plant in western Kentucky, where it removed over 98% of TCE from contaminated soil.

Holton, W C

1999-01-01

75

Perchloroethylene-contaminated drinking water and the risk of breast cancer: additional results from Cape Cod, Massachusetts, USA.  

PubMed Central

In 1998 we published the results of a study suggesting an association between breast cancer and perchloroethylene (PCE; also called tetrachloroethylene) exposure from public drinking water. The present case-control study was undertaken to evaluate this association further. The cases were composed of female residents of eight towns in the Cape Cod region of Massachusetts who had been diagnosed with breast cancer from 1987 through 1993 (n = 672). Controls were composed of demographically similar women from the same towns (n = 616). Women were exposed to PCE when it leached from the vinyl lining of water distribution pipes from the late 1960s through the early 1980s. A relative delivered dose of PCE that entered a home was estimated using an algorithm that took into account residential history, water flow, and pipe characteristics. Small to moderate elevations in risk were seen among women whose exposure levels were above the 75th and 90th percentiles when 0-15 years of latency were considered (adjusted odds ratios, 1.5-1.9 for > 75th percentile, 1.3-2.8 for > 90th percentile). When data from the present and prior studies were combined, small to moderate increases in risk were also seen among women whose exposure levels were above the 75th and 90th percentiles when 0-15 years of latency were considered (adjusted odds ratios, 1.6-1.9 for > 75th percentile, 1.3-1.9 for > 90th percentile). The results of the present study confirm those of the previous one and suggest that women with the highest PCE exposure levels have a small to moderate increased risk of breast cancer.

Aschengrau, Ann; Rogers, Sarah; Ozonoff, David

2003-01-01

76

Indoor perchloroethylene accumulation from dry cleaned clothing on residential premises  

Microsoft Academic Search

Perchloroethylene in the residential environment mainly comes from dry-cleaned clothing. The study aimed at determining the respective perchloroethylene levels and their decay characteristics in three bedrooms set-ups which represented typical Hong Kong domestic premises. Selection of the bedrooms and choices of dry-cleaned clothing arrangement were based on results from a territory wide telephone survey. Two of the bedrooms had window

Christopher Y. H Chao; Thomas C. W Tung; J. L Niu; S. W Pang; Raymond Y. M Lee

1998-01-01

77

Physiological Adaptation of Desulfitobacterium hafniense Strain TCE1 to Tetrachloroethene Respiration?†  

PubMed Central

Desulfitobacterium spp. are ubiquitous organisms with a broad metabolic versatility, and some isolates have the ability to use tetrachloroethene (PCE) as terminal electron acceptor. In order to identify proteins involved in this organohalide respiration process, a comparative proteomic analysis was performed. Soluble and membrane-associated proteins obtained from cells of Desulfitobacterium hafniense strain TCE1 that were growing on different combinations of the electron donors lactate and hydrogen and the electron acceptors PCE and fumarate were analyzed. Among proteins increasingly expressed in the presence of PCE compared to fumarate as electron acceptor, a total of 57 proteins were identified by mass spectrometry analysis, revealing proteins involved in stress response and associated regulation pathways, such as PspA, GroEL, and CodY, and also proteins potentially participating in carbon and energy metabolism, such as proteins of the Wood-Ljungdahl pathway and electron transfer flavoproteins. These proteomic results suggest that D. hafniense strain TCE1 adapts its physiology to face the relative unfavorable growth conditions during an apparent opportunistic organohalide respiration.

Prat, Laure; Maillard, Julien; Grimaud, Regis; Holliger, Christof

2011-01-01

78

HORIZONTAL LASAGNA^TM TO BIOREMEDIATE TCE  

EPA Science Inventory

Removal of TCE from these tight clay soils has been technically difficult and expensive. However, the LASAGNA technique allows movement of the TCE into treatment zones for biodegradation or dechlorination in place, lessening the costs and exposure to TCE. Electroosmosis wa...

79

TEMPERATURE DEPENDENCE OF THE EMISSION OF PERCHLOROETHYLENE FROM DRY CLEANED FABRICS  

EPA Science Inventory

The article discusses an evaluation of the emission of perchloroethylene (tetrachloroethylene) from freshly dry cleaned fabrics using small environment test chambers. he temperature dependence of the release of perchloroethylene was evaluated over a temperature range of 20 to 45 ...

80

Hepatic ultrasonic changes in workers exposed to perchloroethylene.  

PubMed Central

OBJECTIVE--To determine if subclinical hepatotoxicity is associated with exposure to perchloroethylene at concentrations commonly experienced in the workplace, and whether surveillance with serum hepatic transaminase activity underestimates such effects. METHODS--Hepatic parenchymal echogenicity on ultrasonography and serum hepatic transaminase activity were compared in 29 community based dry cleaning operators exposed to perchloroethylene, and a control group of 29 non-exposed laundry workers. Perchloroethylene exposure was assessed by work history and air monitoring. RESULTS--Mean hepatic transaminase activities were minimally increased in dry cleaners compared with laundry workers. Increased alanine aminotransferase activities, between 1.0 and 1.5 times the normal limits, were found in five of 27 (19%) dry cleaners compared with one of 26 (4%) laundry workers. In contrast, diffuse parenchymal changes in echogenicity, as determined by hepatic ultrasonography, were increased nearly twofold in dry cleaners, occurring in 18 of 27 (67%) dry cleaners compared with 10 of 26 (39%) laundry workers (P < 0.05), and were most strongly associated with increased perchloroethylene exposure in older dry to dry or wet transfer operations (odds ratio 4.2, 95% confidence interval 1.1-15.3). Mean eight hour time weighted average perchloroethylene exposure for dry cleaners was 16 ppm, which is less than the permissible exposure limit of 100 ppm in the United States. CONCLUSIONS--It was concluded that mild to moderate hepatic parenchymal changes occur more frequently in workers exposed to perchloroethylene than in populations not exposed to chemical solvents, and that these effects are underestimated by serum hepatic transaminase activity. Images Figure 1

Brodkin, C A; Daniell, W; Checkoway, H; Echeverria, D; Johnson, J; Wang, K; Sohaey, R; Green, D; Redlich, C; Gretch, D

1995-01-01

81

Complete degradation of tetrachloroethene by combining anaerobic dechlorinating and aerobic methanotrophic enrichment cultures  

Microsoft Academic Search

Degradation of tetrachloroethene (perchloroethylene, PCE) was investigated by combining the metabolic abilities of anaerobic\\u000a bacteria, capable of reductive dechlorination of PCE, with those of aerobic methanotrophic bacteria, capable of co-metabolic\\u000a degradation of the less-chlorinated ethenes formed by reductive dechlorination of PCE. Anaerobic communities reductively dechlorinating\\u000a PCE, trichloroethene (TCE) and dichloroethenes were enriched from various sources. The maximum rates of dechlorination

J. Gerritse; V. Renard; J. C. Gottschal; J. Visser

1995-01-01

82

Potential of the TCE-degrading endophyte Pseudomonas putida W619-TCE to improve plant growth and reduce TCE phytotoxicity and evapotranspiration in poplar cuttings  

SciTech Connect

The TCE-degrading poplar endophyte Pseudomonas putida W619-TCE was inoculated in poplar cuttings, exposed to 0, 200 and 400 mg l{sup -1} TCE, that were grown in two different experimental setups. During a short-term experiment, plants were grown hydroponically in half strength Hoagland nutrient solution and exposed to TCE for 3 days. Inoculation with P. putida W619-TCE promoted plant growth, reduced TCE phytotoxicity and reduced the amount of TCE present in the leaves. During a mid-term experiment, plants were grown in potting soil and exposed to TCE for 3 weeks. Here, inoculation with P. putida W619-TCE had a less pronounced positive effect on plant growth and TCE phytotoxicity, but resulted in strongly reduced amounts of TCE in leaves and roots of plants exposed to 400 mg l{sup -1} TCE, accompanied by a lowered evapotranspiration of TCE. Dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA), which are known intermediates of TCE degradation, were not detected. The endophyte P. putida W619-TCE degrades TCE during its transport through the xylem, leading to reduced TCE concentrations in poplar, and decreased TCE evapotranspiration.

Weyens, N.; van der Lelie, D.; Truyens, S.; Dupae, J.; Newman, L.; Taghavi, S.; Carleer, R.; Vangronsveld, J.

2010-09-01

83

Degradation of PCE by Two Kinds of Anaerobic Bacteria  

NASA Astrophysics Data System (ADS)

Anaerobic decomposition of PCE was examined using Clostridium bifermentans DPH-1 with degradation ability of PCE to cis-1,2-dichloroethylene (DCE) and cis-DCE decomposing bacterium, Clostridium sp. strain KYT-1. In the serial 2 step reactions, it was demonstrated that PCE was degraded completely by Clostridium bifermentans DPH-1 in the first reaction and 39% of cis-DCE, byproduct of PCE degrading was eliminated by Clostridium sp. strain KYT-1 in the second reaction with glucose provided as carbon source. On the other hand, in the mixed culture of anaerobic bacteria, PCE was not eliminated perfectly and remained as much as 33% of initial concentration of PCE. But the accumulation of cis-DCE and VC as intermediate metabolites of PCE degradation was not shown.

Kim, Eun-Sook; Takaoka, Hidemitsu; Takamizawa, Kazuhiro

84

Selection of trichloroethene (TCE) degrading bacteria that resist inactivation by TCE  

Microsoft Academic Search

Two isoprene (2-methyl-1,3-butadiene) utilizing bacteria, Alcaligenes denitrificans ssp. xylosoxidans JE 75 and Rhodococcus erythropolis JE 77, were identified as highly efficient cooxidizers of TCE, cis- and transdichloroethene, 1,1-dichloroethene and vinylchloride. Isoprene grown cells eliminate chloride from TCE in stoichiometric amounts and tolerate high concentrations of TCE.

Jens Ewers; Doris Freier-Schriider; Hans-Joachim Knackmuss

1990-01-01

85

INHIBITORY EFFECTS OF PERCHLOROETHYLENE ON HUMAN NEURONAL NICOTINIC ACETYLCHOLINE RECEPTORS.  

EPA Science Inventory

Perchloroethylene (PERC) is a volatile organic solvent with a variety of industrial uses. PERC exposure has been shown to cause adverse neurological effects including deficits in vision and memory in exposed individuals. Despite knowledge of these effects, the mechanisms by whi...

86

Spontaneous abortion in dry cleaning workers potentially exposed to perchloroethylene  

Microsoft Academic Search

OBJECTIVES: To investigate the association between spontaneous abortion and work within dry cleaning units in the United Kingdom where the solvent perchloroethylene is used. METHODS: A retrospective occupational study of reproductive outcome in 7305 women aged 16 and 45 years, who were currently or previously employed in dry cleaning or laundry units in the United Kingdom. Data on workplace exposures

P Doyle; E Roman; V Beral; M Brookes

1997-01-01

87

SOURCES, EMISSION AND EXPOSURE TO TRICHLOROETHYLENE (TCE) AND RELATED CHEMICALS  

EPA Science Inventory

This report documents the sources, emission, environmental fate and exposures for TCE, some of its metabolites, and some other chemicals known to produce identical metabolites. The major findings for TCE are: The primary sources releasing TCE to the environment ...

88

Influence of sediment reduction on TCE degradation  

SciTech Connect

A field-scale remediation technique for TCE and chromate is currently being implemented which uses a chemical treatment to reduce existing iron(III) in sediments. While reduction of some contaminants is well established, TCE data show that dechlorination is more complex, and the role of iron oxides to catalyze the reaction is not well understood. The purpose of this laboratory-scale study was to investigate the influence of temperature and partial sediment reduction on TCE dechlorination. Fully reduced sediments can degrade TCE at sufficiently fast rates (1.2 to 19 h) during static and transport experiments over 2oC to 25oC that a successful barrier could be made at the field scale. In contrast, partially reduced sediment resulted in up to a 3 order of magnitude decrease in the TCE dechlorination rate. While minimally reduced sediment had nearly no TCE reactivity, > 40% reduced sediment had considerably faster dechlorination rates. The second-order dependence of the TCE dechlorination rate on the fraction of reduced iron demonstrates the significant role of the iron oxide surface (as a catalyst or for surface coordination) for TCE dechlorination. Based on these results, the field-scale reduction was designed with specific reagent concen-trations, temperature, and flow rates to efficiently create a reductive barrier.

Szecsody, James E.; Williams, Mark D.; Fruchter, Jonathan S.; Vermeul, Vincent R.; Evans, J. C.; Sklarew, Deborah S.

2000-12-01

89

In situ biodegradation of TCE contaminated groundwater  

Microsoft Academic Search

Trichloroethylene (TCE) is one of the most widely used chlorinated solvents; it is also a common groundwater contaminant. TCE-contaminated groundwater is presently treated by transferring the solvent either to a solid (carbon adsorption) or to the atmosphere (air stripping). Biological treatment of the contaminated water is an alternative that causes complete destruction of the solvent. When performed within the aquifer

Michael J. Nelson; John V. Kinsella; Terry Montoya

1990-01-01

90

Simulating Metabolic Reductive Decholorination with Multiple Cultures during Bioenhanced PCE-NAPL Dissolution  

NASA Astrophysics Data System (ADS)

A recently conducted laboratory experiment investigating metabolic reductive dechlorination in dense non-aqueous phase liquid (DNAPL) source zones demonstrated enhanced DNAPL dissolution by increasing the driving force for mass transfer due to reductions in the aqueous phase. Tetrachloroethene (PCE) was degraded sequentially to cis-1,2-dichloroethene (cis-DCE) through trichloroethylene (TCE) and to ethene via vinyl chloride (VC) by Geobacter and Dehalococcoides, respectively. Significant PCE dechlorination led to bioenhanced DNAPL dissolution, with a 5-fold increase in dissolution observed relative to an abiotic system. A multiphase, compositional simulator, the Michigan Subsurface Environmental Simulator (MISER), was modified to model 9 chemical constituents and 3 microbial populations (a fermentor and two dechlorinators) within the column. Monod kinetics, including electron donor thresholds, electron acceptor competition, and competitive inhibition, were used to model contaminant dechlorination and biomass growth. The model was calibrated to the experimental data using effluent concentrations. Model results were compared to analyses of side port samples collected along the column length to determine the ability of the model to reproduce the biomass growth and reductive dechlorination occurring within the column. Results suggest that the model as formulated is capable of capturing the general trends observed in the column. Work is on-going to investigate the influence of initial biomass distribution, DNAPL source zone distribution, and applied boundary conditions on bioenhanced dissolution predictions. This model is expected to provide valuable insights for future experimental design and identification of conditions that may govern bioenhanced dissolution in the field.

Chen, M.; Abriola, L.; Christ, J.; Amos, B. K.; Suchomel, E. J.; Pennell, K. D.; Loeffler, F.

2009-12-01

91

Infiltration of PCE in a system containing spatial wettability variations  

Microsoft Academic Search

A two-dimensional infiltration experiment was conducted to investigate and quantify the effect of spatial wettability variations on DNAPL migration and entrapment in saturated sands. Experimental observations of tetrachloroethylene (PCE) infiltration showed that organic-wet sand lenses acted as very effective capillary barriers, retaining PCE and inhibiting its downward migration. A multiphase numerical simulator was used to model this sand box experiment.

Denis M. O'Carroll; Scott A. Bradford; Linda M. Abriola

2004-01-01

92

PCE oxidation by sodium persulfate in the presence of solids.  

PubMed

Batch reactor experiments were performed to determine the effects of solids on the oxidation of tetracholoroethylene (PCE) by sodium persulfate in aqueous solution. Based on the rates of PCE degradation and chloride formation, PCE oxidation by heat-activated sodium persulfate at 50 °C in the presence of solids ranged from no detectable oxidation of PCE to the levels observed in water-only reactors. Repeated doses of sodium persulfate, undertaken to overcome the inherent solids oxidant demand, improved the rate and extent of PCE oxidation in reactors containing reference solids; however, no improvement was observed in reactors containing field soils. Additionally, no improvements in PCE oxidation were observed after pretreating Great Lakes and Appling soils with ca. 15 g/kg of sodium persulfate or 30% hydrogen peroxide to remove oxidizable fractions, or acetic acid to remove the carbonate fraction. Based on these results, in situ treatment of Great Lakes and Appling soils with heat-activated sodium persulfate is not anticipated to result in substantial PCE oxidation, while in situ treatment of Fort Lewis soils is anticipated to result in PCE oxidation. This work demonstrates the need to perform soil-specific contaminant treatability tests rather than soil oxidant demand tests when determining oxidant dosage requirements. PMID:21070044

Costanza, Jed; Otaño, Gretell; Callaghan, John; Pennell, Kurt D

2010-11-11

93

Hydrogen peroxide treatment of TCE contaminated soil  

SciTech Connect

Solvent contaminated soils are ubiquitous in the industrial world and represent a significant environmental hazard due to their persistence and potentially negative impacts on human health and the environment. Environmental regulations favor treatment of soils with options which reduce the volume and toxicity of contaminants in place. One such treatment option is the in-situ application of hydrogen peroxide to soils contaminated with chlorinated solvents such as trichloroethylene (TCE). This study investigated hydrogen peroxide mass loading rates on removal of TCE from soils of varying organic matter content. Batch experiments conducted on contaminated loam samples using GC headspace analysis showed up to 80% TCE removal upon peroxide treatment. Column experiments conducted on sandy loam soils with high organic matter content showed only 25% TCE removal, even at hydrogen peroxide additions of 25 g peroxide per kg soil.

Hurst, D.H.; Robinson, K.G. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Civil Engineering; Siegrist, R.L. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.

1993-12-31

94

Monitoring Anaerobic TCE Degradation by Evanite Cultre in Column Packed with TCE-Contaminated Soil  

NASA Astrophysics Data System (ADS)

Trichloroethylene (TCE) is a long-term common groundwater pollutant because the compound with high density is slowly released into groundwater. Physical and chemical remediation processes have been used to clean-up the contaminant, but novel remediation technology is required to overcome a low efficiency of the traditional treatment process. Many researchers focused on biological process using an anaerobic TCE degrading culture, dehalococcoides spp., but it still needs to evaluate whether the process can be applied into field scale under aerobic condition. Therefore, in this work we examined two different types (i.e., Natural attenuation and bioaugmentation) of biological remediation process in anaerobic column packed with TCE-contaminated soil. A TCE degradation by indigenous microorganisms was confirmed by monitoring TCE and the metabolites (c-DCE, VC, ETH). However, TCE was transformed and stoichiometry amount of c-DCE was produced, and VC and ETH was not detected. To test bioaugmentation of Evanite culture containing dehalococcoides spp., Evanite culture was injected into the column and TCE degradation to c-DCE, VC, ETH was monitored. We are evaluating the transport of the Evanite culture in the column by measuring TCE and VC reductases. In the result, the TCE was completely degraded to ETH using hydrogen as electron donor generate by hydrogen-production fermentation from formate.

Ko, J.; Han, K.; Ahn, G.; Park, S.; Kim, N.; Ahn, H.; Kim, Y.

2011-12-01

95

Cometabolic degradation of TCE and DCE without intermediate toxicity  

Microsoft Academic Search

Trichloroethylene (TCE) and cis-1,2-dichloroethylene (DCE) cometabolic degradation by a filamentous, phenol-oxidizing enrichment from a surface-water source were investigated in batch tests. No intermediate toxicity effects were evident during TCE or DCE degradation for loadings up to 0.5 mg TCE\\/mg VSS or 0.26 mg DCE\\/mg VSS. Phenol addition up to 40 mg\\/L did not inhibit TCE or DCE degradation. TCE specific

A. R. Bielefeldt; H. D. Stensel; S. E. Strand

1995-01-01

96

Activated carbon adsorption of trichloroethylene (TCE) vapor stripped from TCE-contaminated water  

Microsoft Academic Search

Ground water contaminated with trichloroethylene (TCE) used in electronic, electric, dry cleaning and the like industries is often treated by air-stripping. In this treatment process, TCE in its vapor form is stripped from ground water by air stream and sometimes emitted into the atmosphere without any additional treatments. Activated carbon adsorption is one of the practical and useful processes for

Yusaku Miyake; Akiyoshi Sakoda; Hiroaki Yamanashi; Hirotaka Kaneda; Motoyuki Suzuki

2003-01-01

97

BIODEGRADATION OF PCE AND TCE IN LANDFILL, LEACHATE PREDICTED FROM CONCENTRATIONS OF MOLECULAR HYDROGEN: A CASE STUDY  

EPA Science Inventory

The Refuse Hideaway Landfill (23-acre) was designed as a "natural attenuation" landfill and no provision was made to collect and treat contaminated water. Natural biological degradation through sequential reductive dechlorination had been an important mechanism for natural atten...

98

Effect of source variability and transport processes on carbon isotope ratios of TCE and PCE in two sandy aquifers  

Microsoft Academic Search

Chlorinated ethenes often migrate over extended distances in aquifers and may originate from different sources. The aim of this study was to determine whether stable carbon isotope ratios remain constant during dissolution and transport of chlorinated ethenes and whether the ratios can be used to link plumes to their sources. Detailed depth-discrete delineation of the carbon isotope ratio in a

D. Hunkeler; N. Chollet; X. Pittet; R. Aravena; J. A. Cherry; B. L. Parker

2004-01-01

99

Infiltration of PCE in a system containing spatial wettability variations  

Microsoft Academic Search

Abstract A two-dimensional infiltration experiment was conducted to investigate and quantify the effect of spatial wettability variations on DNAPL migration and entrapment in saturated sands. Experimental observations of tetrachloroethylene (PCE) infiltration showed,that organic-wet sand lenses acted as very effective capillary barriers, retaining PCE and inhibiting its downward migration. A multiphase numerical,simulator was,used to model,this sand box,experiment. The simulator incorporates wettability-modified

Denis M. O'Carroll; Scott A. Bradford; Linda M. Abriola

100

Effect of trichloroethylene (TCE) and toluene concentrations on TCE and toluene biodegradation and the population density of TCE and toluene degraders in soil  

SciTech Connect

Toluene is one of several cosubstrates able to support the cometabolism of trichloroethylene (TCE) by soil microbial communities. Indigenous microbial populations in soil degraded TCE in the presence, but not the absence, of toluene after a 60- to 80-h lag period. Initial populations of toluene and TCE degraders ranged from 0.2 x 10{sup 3} to 4 x 10{sup 3} cells per g of soil and increased by more than 4 orders of magnitude after the addition of 20 {mu}g of toluene and 1 {mu}g of TCE per mol of soil solution. The numbers of TCE and toluene degraders and the percent removal of TCE increased with an increase in initial toluene concentration. As the initial TCE concentration was increased from 1 to 20 {mu}g/ml, the numbers of toluene and TCE degraders and the rate of toluene degradation decreased, and no TCE degradation occurred. No toluene or TCE degradation occurred at a TCE concentration of 50 {mu}g/ml. 22 refs., 3 figs., 2 tabs.

Mu, D.Y.; Scow, K.M. [Univ. of California, Davis, CA (United States)

1994-07-01

101

Occupational exposure to perchloroethylene in the dry cleaning industry.  

PubMed

Field surveys were conducted of 67 dry cleaning establishments to assess working conditions and potential for exposure to perchloroethylene, a solvent of choice in this industry. Evaluation of ventilation controls showed that 28% of cleaning machines (transfer type) did not have functioning local exhaust systems, and an additional 32% had inadequately maintained systems providing less than the recommended face velocity at the door opening. Personal sampling was performed in 20 firms to relate operator exposure levels to the process used and degree of local exhaust ventilation. Utilization of the dry-to-dry (closed system) process resulted in a lower mean TWA exposure, 28.3 ppm, as compared to 86.6 ppm for transfer operations. Five-minute peak samples taken during clothing transfer demonstrated significant exposure levels ranging from 11.3 to 533.8 ppm. A lower mean peak exposure (25.3 ppm) was found for firms with local exhaust ventilation at the recommended rate than for facilities with poorly or unventilated cleaning machines (159.7 ppm). The study points out the manner in which available control measures can be used optimally to reduce employee exposure. Increased involvement of trade associations and local health authorities is also recommended to promote the safe use of perchloroethylene in the dry cleaning industry. PMID:4003279

Materna, B L

1985-05-01

102

National Exposure Registry Trichloroethylene (TCE) Subregistry Baseline through Followup 3.  

National Technical Information Service (NTIS)

This report provides an overview of the ATSDR Trichloroethylene (TCE) Subregistry population for Baseline through Followup 3 activities, and the results of the comparison of reporting rates of health outcomes with national norms. The TCE Subregistry inclu...

1999-01-01

103

TCE decomposition by the nonthermal plasma process concerning ozone effect  

Microsoft Academic Search

Dilute trichloroethylene (TCE) and other volatile organic compounds (VOC) in air were decomposed by using the nonthermal plasma process combined with catalysts. To enhance the energy efficiency of the TCE decomposition, some catalysts were tested including their location. It was found that the newly proposed indirect process (VOC cannot be exposed in the plasma region) can also decompose TCE and

Testuji Oda; Tadashi Takahashi; Kei Yamaji

2004-01-01

104

3D-CSIA: Carbon, Chlorine, and Hydrogen Isotope Fractionation in Transformation of TCE to Ethene by a Dehalococcoides Culture.  

PubMed

Carbon (C), chlorine (Cl), and hydrogen (H) isotope effects were determined during dechlorination of TCE to ethene by a mixed Dehalococcoides (Dhc) culture. The C isotope effects for the dechlorination steps were consistent with data published in the past for reductive dechlorination (RD) by Dhc. The Cl effects (combined with an inverse H effect in TCE) suggested that dechlorination proceeded through nucleophilic reactions with cobalamin rather than by an electron transfer mechanism. Depletions of (37)Cl in daughter compounds, resulting from fractionation at positions away from the dechlorination center (secondary isotope effects), further support the nucleophilic dechlorination mechanism. Determination of C and Cl isotope ratios of the reactants and products in the reductive dechlorination chain offers a potential tool for differentiation of Dhc activity from alternative transformation mechanisms (e.g., aerobic degradation and reductive dechlorination proceeding via outer sphere mechanisms), in studies of in situ attenuation of chlorinated ethenes. Hydrogenation of the reaction products (DCE, VC, and ethene) showed a major preference for the (1)H isotope. Detection of depleted dechlorination products could provide a line of evidence in discrimination between alternative sources of TCE (e.g., evolution from DNAPL sources or from conversion of PCE). PMID:23895211

Kuder, Tomasz; van Breukelen, Boris M; Vanderford, Mindy; Philp, Paul

2013-08-23

105

Pharmacokinetic/Mechanism-Based Analysis of the Carcinogenic Risk of Perchloroethylene,  

National Technical Information Service (NTIS)

The implications of existing pharmacokinetic information for the human carcinogenic risk of perchloroethylene were explored using physiologically based pharmacokinetic modeling. The models used were easily implemented on the Apple MacIntosh microcomputer ...

D. Hattis S. Tuler L. Finkelstein Z. O. Luo

1986-01-01

106

The temperature dependence of the emission of perchloroethylene from dry cleaned fabrics.  

PubMed

A study was conducted to evaluate the emission of perchloroethylene (tetrachloroethylene) from freshly dry cleaned fabrics using small environmental test chambers. The temperature dependence of the release of perchloroethylene was evaluated over a temperature range of 20 to 45 degrees C. A linear relation exists between the logarithm of perchloroethylene retention time (tau) and the reciprocal of the absolute temperature (1/T). The temperature dependence of the retention time can be expressed as tau = 2.36 x 10(-16)e13,892/T and 8.38 x 10(-9)e8766/T sec for 100% wool and 55% polyester/45% wool fabrics, respectively. These results indicate that "airing out" freshly dry cleaned fabrics at temperatures near 20 degrees C for short time periods (e.g., 5 hr) will not appreciably reduce the total emissions of perchloroethylene. PMID:2351125

Guo, Z S; Tichenor, B A; Mason, M A; Plunket, C M

1990-06-01

107

Two-Year Evolution of Perchloroethylene-lnduced Color-Vision Loss  

Microsoft Academic Search

Progression of perchloroethylene-induced color-vision impairment was studied in 33 dry-cleaner workers at 12 establishments in Modena, Italy. In an initial survey, we evaluated exposure with personal passive samplers, and we assessed color vision with the Lanthony D-15 desaturated panel. Two years later, workers were reexamined. In 19 workers (subgroup A), exposure to perchloroethylene had increased (median of 1.7 ppm versus

Fabriziomaria Gobba; Elena Righi; Guglielmina Fantuzzi; Guerrino Predieri; Lucia Cavazzuti; Gabriella Aggazzotti

1998-01-01

108

Occupational exposure to perchloroethylene in dry-cleaning shops in Tehran, Iran.  

PubMed

Perchloroethylene, the most widely used solvent in dry cleaning, is toxic to the liver, kidneys and central nervous system and may be a human carcinogen. An exposure assessment was carried out in 69 dry-cleaning shops using perchloroethylene in Tehran city, Iran. The 8-h time weighted average (TWA) breathing zone air samples and end-exhaled air samples were obtained from 179 workers who worked as the job titles included machine operator (n=71), presser (n=63) and counter area (clerk) (n=45). The mean perchloroethylene concentrations in breathing zone air were 11.5 ppm, 9.6 ppm and 7.2 ppm respectively. The mean perchloroethylene concentrations in end-exhaled air of the same participants in Saturday morning (prior to shift of workweek) were 1.7 ppm, 1.5 ppm and 1.1 ppm, but in Thursday evening (end of shift at end of workweek) were 2.4 ppm, 2.0 ppm and 1.5 ppm respectively. This study found that, the mean perchloroethylene concentrations in breathing zone air and end-exhaled air in the dry-cleaning workers were lower than the TLV (25 ppm) and BEI (5 ppm) recommended by ACGIH. Regression analysis showed that the concentration of perchloroethylene in breathing zone air (TWA) was highly and significantly correlated with the concentration of perchloroethylene in end-exhaled air in Saturday morning with a regression equation Y=0.147X + 0.031 (r=0.99, p<0.001) and also in Thursday evening with a regression equation Y=0.201X + 0.072 (r=0.98, p<0.001) where X is the concentration of perchloroethylene in breathing zone air and Y is that the concentration of perchloroethylene in end-exhaled air. The results also showed the potential utility of measuring the concentration of perchloroethylene in end-exhaled air as a method for assessing relative exposure in dry cleaning shops which use it. PMID:19367044

Azimi Pirsaraei, Seyed Reza; Khavanin, Ali; Asilian, Hassan; Soleimanian, Ardalan

2009-04-01

109

Well Installation and Sampling Report for Monitoring Wells TCM6 TCM7, and TNX 28D - 40D and GeoSiphon Cell TGSC-2  

SciTech Connect

The shallow groundwater and sediments beneath the TNX Area are contaminated with both dissolved and residual chlorinated volatile organic compounds (CVOCs) such as trichloroethylene (TCE), carbon tetrachloride and perchloroethylene (PCE). The Savannah River Technology Center (SRTC) is studying a new technology for remediating CVOCs known as GeoSiphon.

Nichols, R.L.

1999-09-20

110

Methanotrophic TCE biodegradation in a multi-stage bioreactor  

SciTech Connect

A two-stage bioreactor system was continuously fed a solution of TCE (concentrations ranging between 0.2 and 20 mg L{sup -1}) at 2 mL min{sup -1}; the system utilized a mutant (PP358) of the methane oxidizing bacterium Methylosinus trichosporium OB3b for the fortuitous cooxidation of TCE by the enzyme-soluble methane monooxygenase (sMMO). A methane-free environment was maintained in the TCE treatment portion of the reactor (plug-flow columns), minimizing the effects of competitive inhibition between TCE and methane for the sMMO. The reactor was operated in two separate flow configurations, single-pass and cross-flow, with TCE removal percentages exceeding 78% (for a TCE feed concentration of 20 mg L{sup -1}) and 93% (for a TCE feed concentration of 10 mg L{sup -1}), respectively. A r{sub max} of 109.4 mg of TCE (g of VS){sup -1} d{sup -1} for a TCE feed concentration of 20 mg L{sup -1} was obtained, suggesting that high rates of degradation occurred within the reactor. TCE-induced toxicity effects occurred at TCE feed concentrations of 10 mg L{sup -1} and greater, resulting in declines of the biomass concentrations and the enzyme activities. A model describing the rate of TCE degradation in the plug-flow columns was proposed by Alvarez-Cohen et al. and was modified to incorporate the suboptimal activities of sMMO. 29 refs., 7 figs., 1 tab.

Tschantz, M.L.F.; Bowman, J.P.; Bienkowski, P.R.; Sayler, G.S. [Univ. of Tennessee, Knoxville, TN (United States); Donaldson, T.L.; Strong-Gunderson, J.M.; Palumbo, A.V.; Herbes, S.E. [Oak Ridge National Lab., TN (United States)

1995-08-01

111

TCE degradation in a methanotrophic attached-film bioreactor  

Microsoft Academic Search

Trichloroethene was degraded in expanded-bed bioreactors operated with mixed-culture methanotrophic attached films. Biomass concentrations of 8 to 75 g volatile solids (VS) per liter static bed (L[sub sb]) were observed. Batch TCE degradation rates at 35C followed the Michaelis-Menten model, and a maximum TCE degradation rate (q[sub max]) of 10.6 mg TCE\\/gVS [center dot] day and a half velocity coefficient

Donna E. Fennell; Yarrow M. Nelson; Sheila E. Underhill; Thomas E. White; William J. Jewell

1993-01-01

112

Methanotrophic TCE biodegradation in a multi-stage bioreactor  

Microsoft Academic Search

A two-stage bioreactor system was continuously fed a solution of TCE (concentrations ranging between 0.2 and 20 mg L⁻¹) at 2 mL min⁻¹; the system utilized a mutant (PP358) of the methane oxidizing bacterium Methylosinus trichosporium OB3b for the fortuitous cooxidation of TCE by the enzyme-soluble methane monooxygenase (sMMO). A methane-free environment was maintained in the TCE treatment portion of

Michael F. Tschantz; John P. Bowman; P. R. Bienkowski; G. S. Sayler; T. L. Donaldson; J. M. Strong-Gunderson; A. V. Palumbo; S. E. Herbes

1995-01-01

113

Molecular biomarker-based biokinetic modeling of a PCE-dechlorinating and methanogenic mixed culture.  

PubMed

Bioremediation of chlorinated ethenes via anaerobic reductive dechlorination relies upon the activity of specific microbial populations--most notably Dehalococcoides (DHC) strains. In the lab and field Dehalococcoides grow most robustly in mixed communities which usually contain both fermenters and methanogens. Recently, researchers have been developing quantitative molecular biomarkers to aid in field site diagnostics and it is hoped that these biomarkers could aid in the modeling of anaerobic reductive dechlorination. A comprehensive biokinetic model of a community containing Dehalococcoides mccartyi (formerly D. ethenogenes) was updated to describe continuously fed reactors with specific biomass levels based on quantitative PCR (qPCR)-based population data (DNA and RNA). The model was calibrated and validated with subsets of chemical and molecular biological data from various continuous feed experiments (n = 24) with different loading rates of the electron acceptor (1.5 to 482 ?eeq/L-h), types of electron acceptor (PCE, TCE, cis-DCE) and electron donor to electron acceptor ratios. The resulting model predicted the sum of dechlorination products vinyl chloride (VC) and ethene (ETH) well. However, VC alone was under-predicted and ETH was over predicted. Consequently, competitive inhibition among chlorinated ethenes was examined and then added to the model. Additionally, as 16S rRNA gene copy numbers did not provide accurate model fits in all cases, we examined whether an improved fit could be obtained if mRNA levels for key functional enzymes could be used to infer respiration rates. The resulting empirically derived mRNA "adjustment factors" were added to the model for both DHC and the main methanogen in the culture (a Methanosaeta species) to provide a more nuanced prediction of activity. Results of this study suggest that at higher feeding rates competitive inhibition is important and mRNA provides a more accurate indicator of a population's instantaneous activity than 16S rRNA gene copies alone as biomass estimates. PMID:23363057

Heavner, Gretchen L W; Rowe, Annette R; Mansfeldt, Cresten B; Pan, Ju Khuan; Gossett, James M; Richardson, Ruth E

2013-03-26

114

77 FR 6863 - Proposed Collection; Comment Request for VITA/TCE Program Forms  

Federal Register 2010, 2011, 2012, 2013

...Proposed Collection; Comment Request for VITA/TCE Program Forms AGENCY: Internal Revenue...the IRS is soliciting comments concerning VITA/TCE Program Forms 14310, 8653, 8654...gov. SUPPLEMENTARY INFORMATION: Title: VITA/TCE Program Forms. OMB Number:...

2012-02-09

115

Expert system methodology for evaluating reductive dechlorination at TCE sites  

Microsoft Academic Search

An expert knowledge site-screening methodology has been developed to evaluate naturally occurring reductive dechlorination as a remedial option for sites with TCE-contaminated groundwater. This methodology combines a causative model for the reductive dechlorination of TCE and expert knowledge within a Bayesian Belief Network. The knowledge base for this expert system was obtained from 22 experts via an expert elicitation protocol

Neil A. Stiber; Marina Pantazidou; Mitchell J. Small

1999-01-01

116

PERCHLOROETHYLENE (PERC) INHIBITS FUNCTION OF VOLTAGE-GATED CALCIUM CHANNELS IN PHEOCHROMOCYTOMA CELLS.  

EPA Science Inventory

The industrial solvent perchloroethylene (PERC) is listed as a hazardous air pollutant in the 1990 Ammendments to Clean Air Act and is a known neurotoxicant. However, the mechanisms by which PERC alters nervous system function are poorly understood. In recent years, it has been d...

117

AMBIENT PERCHLOROETHYLENE LEVELS INSIDE COIN-OPERATED LAUNDRIES WITH DRYCLEANING MACHINES ON THE PREMISES  

EPA Science Inventory

In this study, ambient perchloroethylene (PERC) levels were measured inside and in the vicinity of six self serve laundries containing coin-type dry cleaning operations. Inside two of the laundries, evaluations of organic vapor monitoring badges were performed in addition to the ...

118

Anaerobic biodegradation of TCE in laboratory columns of fractured saprolite.  

PubMed

An experiment was conducted to determine if biodegradation of trichloroethylene (TCE) can occur in previously uncontaminated ground water in saturated fractured saprolite (highly weathered material derived from sedimentary rocks). Two undisturbed columns (0.23 m diameter by 0.25 m long) of fractured saprolite were collected from approximately 2 m depth at an uncontaminated site on the Oak Ridge Reservation, Oak Ridge, Tennessee. Natural, uncontaminated ground water from the site, which was degassed and spiked with dissolved phase TCE, was continuously pumped through one column containing the natural microbial communities (the biotic column). In a second column, the microorganisms were inhibited and the dissolved phase TCE was added under aerobic conditions (dissolved oxygen conditions > 2 ppm). In effluent from the biotic column, reducing conditions rapidly developed and evidence of anaerobic biodegradation of TCE, by the production of cDCE, first appeared approximately 31 days after addition of TCE. Reductive dechlorination of TCE occurred after iron-reducing conditions were established and about the same time that sulfate reduction began. There was no evidence of methanogenesis. Analyses using polymerase chain reaction with specific primers sets detected the bacteria Geothrix, Geobacter, and Desulfococcus-Desulfonema-Desulfosarcina in the effluent of the biotic column, but no methanogens. The presence of these bacteria is consistent with iron- and sulfate-reducing conditions. In the inhibited column, there were no indicators of TCE degradation. Natural organic matter that occurs in the saprolite and ground water at the site is the most likely primary electron donor for supporting reductive dechlorination of TCE. The relatively rapid appearance of indicators of TCE dechlorination suggests that these processes may occur even in settings where low oxygen conditions occur seasonally due to changes in the water table. PMID:15318776

Lenczewski, Melissa E; McKay, Larry D; Layton, Alice

119

Dechlorination of PCE by Mixed Methanogenic Cultures Using Hollow-Fiber Membranes  

Microsoft Academic Search

The study investigated the use of hollow-fiber membranes for hydrogen (H2) delivery to support the biological reductive dechlorination of tetrachloroethene (PCE) Two experiments were performed in which H2 was supplied through membranes placed in stirred batch reactors containing a mixed methanogenic\\/dechlorinating culture and PCE (?10?µM. Reductive dechlorination of PCE to cis-dichloroethene was sustained in the reactors receiving H2 (1% H2

H. D. Muenzner; L. W. Clapp; R. M. Hozalski; M. J. Semmens; P. J. Novak

2002-01-01

120

Large two-dimensional laboratory experiment with biodegradation of a PCE source zone  

NASA Astrophysics Data System (ADS)

To investigate the effects of bioremediation on DNAPL source zones, we carried out an experiment in a two-dimensional tank filled with sand. A microbial assemblage originating from a contaminated field site was used for inoculation without enrichment. Injection of 250 ml PCE into the tank yielded a residual zone of PCE with a pool at the bottom. After this injection, the tank was continuously flushed with anaerobic water containing sufficient electron donor and various nutrients. Chlorinated ethenes analysis, microbial groups counting, and the visual observation of the colored PCE show that PCE was degraded in the source zone. Bio-enhanced dissolution occurred as cDCE concentrations were measured four times the solubility limit of PCE and because the PCE solubility limit in the source zone increased. Degradation of cDCE to VC and ethene occurred when PCE concentrations were low (<0.1 mM). After one year of experiment, approximately 135 ml of chlorinated ethenes were removed from the tank. PCE left in the tank was 90 ml and was only present in the pool. keywords: 2D tank experiment, PCE-DNAPL, reductive dechlorination, source zone, bio-enhanced dissolution, mobilization.

Langevoort, M.; Hassanizadeh, S.; Kleingeld, P.; Heimovaara, T.; Leijnse, T.

2008-12-01

121

Field demonstration of vapor phase TCE bioreactor. Final report  

SciTech Connect

The objective of this Cooperative Research and Development Agreement (CRADA), was to demonstrate the effectiveness of a vapor-phase bioreactor system for the destruction of trichloroethylene (TCE) from contaminated groundwater. A field demonstration was per-formed using groundwater at the Oak Ridge K-25 Site contaminated with a complex mixture of organic chemicals. This site is managed and operated by Martin Marietta Energy Systems, Inc. for the Department of Energy (DOE). Analysis of the data generated during the test can be summarized in three major observations. First, TCE was degraded in the presence of all the organics found in the steam strip condensate. This was observed during treatment of both the steam strip condensate and condensate amended with TCE to increase its concentration relative to the other components. The conclusion that TCE was being biodegraded was supported by performing mass balance control experiments with the reactor and by tracking recalcitrant chemicals also present in the steam stripper condensate. Second, there appeared to be an initial lag period of up to 24 hours before onset of TCE degradation in the reactor. The source of this lag was not determined but could be related to either an acclimation of the microorganisms to other chemicals found in the condensate or reversible inhibitory effects on TCE degradation. The duration of TCE degradative activity was relatively short for only 2 to 5 days. compared to previous demonstrations where TCE was the sole contaminant. However, several of the runs were interrupted due to mechanical and not biological issues. Third, other chemical contaminants were also degraded. by the bacteria used in the vapor phase reactor which is consistent with previous work performed both at ENVIROGEN and elsewhere.

NONE

1994-12-14

122

Biodegradation of trichloroethylene (TCE) adsorbed on granular activated carbon (GAC)  

Microsoft Academic Search

The objective of this study is to clarify the possibility of biodegradation of TCE adsorbed on granular activated carbon (GAC) and to determine the adsorption capacity of bioregenerated GAC. The amount of desorption and mineralization was estimated to account for 82.5% of the total TCE (26.2 mg) adsorbed in the GAC. It indicates that incinerators were saved from the damage by

Yoichi Nakano; Li Qing Hua; Wataru Nishijima; Eiji Shoto; Mitumasa Okada

2000-01-01

123

Long-term perchloroethylene exposure: a limited meta-analysis of neurobehavorial deficits in occupationally and residentially exposed groups  

EPA Science Inventory

The literature concerning the neurobehavioral and neurophysiological effects of long-term exposure to perchloroethylene (PERC) in humans was meta-analyzed to provide a quantitative review and synthesis. The useable data base from this literature comprised studies reporting effec...

124

Transcriptional Expression of the tceA Gene in a Dehalococcoides-Containing Microbial Enrichment  

Microsoft Academic Search

Dynamic changes in the transcriptional expression of the tceA gene, which encodes a trichloroethene reductive dehalogenase, were characterized in a Dehalococcoides-containing microbial enrichment culture. Expression was quantified by real-time PCR as the number of tceA transcripts per tceA gene. Expression of tceA increased 40-fold after chlorinated ethene-starved cells were exposed to trichloroethene (TCE), cis-dichlo- roethene (DCE), or 1,1-DCE but did

David R. Johnson; Patrick K. H. Lee; Victor F. Holmes; Alexander C. Fortin; Lisa Alvarez-Cohen

2005-01-01

125

Cosolvent effects of alcohols on the Henry's law constant and aqueous solubility of tetrachloroethylene (PCE)  

Microsoft Academic Search

The effects of selected cosolvents ethyl alcohol (EtOH), isopropyl alcohol (IPA), and tertbutyl alcohol (TBA) on the Henry's law constant (H) of tetrachloroethylene (PCE) in aqueous solutions were investigated using the static headspace method. Alcohols in solution at a concentration around 20% and above acted as cosolvents increasing the aqueous solubility of PCE, which resulted in lower H values for

Tarek I Ladaa; Cindy M Lee; John T Coates; Ronald W Falta

2001-01-01

126

Field vapor extraction test and long-term monitoring at a PCE contaminated site  

Microsoft Academic Search

The results of a field investigation, vapor extraction tests, and long-term monitoring at a PCE-contaminated site in Saga, Japan, are reported. The field investigation indicated that PCE likely was trapped in a surface clayey sand layer (vadose zone), and soil vapor extraction (SVE) was adopted as the remediation approach. The field test results the effectiveness of SVE in removing volatile

J.-C. Chai; N. Miura

2004-01-01

127

Genome sequence of the PCE-dechlorinating bacterium Dehalococcoides ethenogenes.  

PubMed

Dehalococcoides ethenogenes is the only bacterium known to reductively dechlorinate the groundwater pollutants, tetrachloroethene (PCE) and trichloroethene, to ethene. Its 1,469,720-base pair chromosome contains large dynamic duplicated regions and integrated elements. Genes encoding 17 putative reductive dehalogenases, nearly all of which were adjacent to genes for transcription regulators, and five hydrogenase complexes were identified. These findings, plus a limited repertoire of other metabolic modes, indicate that D. ethenogenes is highly evolved to utilize halogenated organic compounds and H2. Diversification of reductive dehalogenase functions appears to have been mediated by recent genetic exchange and amplification. Genome analysis provides insights into the organism's complex nutrient requirements and suggests that an ancestor was a nitrogen-fixing autotroph. PMID:15637277

Seshadri, Rekha; Adrian, Lorenz; Fouts, Derrick E; Eisen, Jonathan A; Phillippy, Adam M; Methe, Barbara A; Ward, Naomi L; Nelson, William C; Deboy, Robert T; Khouri, Hoda M; Kolonay, James F; Dodson, Robert J; Daugherty, Sean C; Brinkac, Lauren M; Sullivan, Steven A; Madupu, Ramana; Nelson, Karen E; Kang, Katherine H; Impraim, Marjorie; Tran, Kevin; Robinson, Jeffrey M; Forberger, Heather A; Fraser, Claire M; Zinder, Stephen H; Heidelberg, John F

2005-01-01

128

Two-year evolution of perchloroethylene-induced color-vision loss.  

PubMed

Progression of perchloroethylene-induced color-vision impairment was studied in 33 dry-cleaner workers at 12 establishments in Modena, Italy. In an initial survey, we evaluated exposure with personal passive samplers, and we assessed color vision with the Lanthony D-15 desaturated panel. Two years later, workers were reexamined. In 19 workers (subgroup A), exposure to perchloroethylene had increased (median of 1.7 ppm versus 4.3 ppm, respectively), whereas in the remaining 14 workers (subgroup B) exposure was reduced (2.9 ppm versus 0.7 ppm, respectively). Color vision worsened in subgroup A, but no vision changes were apparent in subgroup B. The results indicated that an increase in exposure during a 2-y period, even if slight, can cause color vision to deteriorate. A similar slight reduction in exposure did not lead to color-vision improvement; perhaps this lack of improvement resulted from (a) an insufficient reduction in exposure, (b) an insufficient reduction in duration of exposure, or (c) irreversible perchloroethylene-induced color-vision loss. PMID:9814715

Gobba, F; Righi, E; Fantuzzi, G; Predieri, G; Cavazzuti, L; Aggazzotti, G

129

Coupling Surfactant Flushing and Bioaugmentation for PCE-DNAPL Source Zone Treatment  

NASA Astrophysics Data System (ADS)

Enhanced solubilization flushing using a biodegradable surfactant (Tween 80) was combined with bioaugmentation to initiate microbial reductive dechlorination and detoxify residual tetrachloroethene (PCE)- dense nonaqueous phase liquid (DNAPL). Dechlorination activity, spatial distribution of Dehalococcoides spp., and down-gradient plume development were monitored in a 2-D aquifer cell equipped with eighteen sampling ports. Saturation distributions of the PCE-DNAPL source zone were quantified using a light transmission system to determine the ganglia-to-pool (GTP) volume ratio, which was approximately 1.5 (i.e., 60% ganglia and 40% pools) prior to surfactant flushing. Flushing with three pore volumes (PVs) of 4% (w/w) Tween 80 solution recovered approximately 55% of the original PCE mass and reduced PCE effluent concentration from saturation (200 mg/L) to less than 50 mg/L. Following the introduction of reduced basal salts medium amended with 10 mM lactate, nine side ports located upstream and within the initial PCE- DNAPL source zone were augmented with Bio-Dechlor INOCULUM (BDI), a PCE-to-ethene dechlorinating consortium. Flux-averaged measurements of aqueous effluent samples revealed the conversion of PCE to cis-dichloroethene (DCE) with minimal lag time (7 days, approx. 1 PV), and vinyl chloride and ethene were detected within 10 PVs after bioaugmentation. Quantitative real-time PCR (qPCR) targeting Dehalococcoides spp. demonstrated growth once aqueous PCE concentrations decreased below inhibitory levels (~540 mM), with significant growth (2 to 4-orders of magnitude) near the remaining source zone. These results demonstrate the successful colonization of a pool-dominated (NAPL saturation >0.13) PCE- DNAPL source zone by a dechlorinating consortium following partial mass removal, and the potential for locally bioenhanced DNAPL dissolution.

Cápiro, N. L.; Granbery, E. K.; Amos, B. K.; Löffler, F. E.; Pennell, K. D.

2008-12-01

130

In Situ Dechlorination of TCE During Aquifer Heating  

SciTech Connect

Laboratory and field efforts were undertaken to examine trichloroethene (TCE) dechlorination as a function of temperature as an aquifer is heated to temperatures approaching boiling. Experiments were conducted using sediment samples during electrical resistance heating (ERH) treatment at the Fort Lewis East Gate Disposal Yard, which contains non-aqueous phase TCE and hydrocarbon contamination. Laboratory microcosms with these sediments showed TCE dechlorination at 70oC with measured products of acetylene, ethene, and ethane, indicating an abiotic component of the degradation. In contrast, TCE was dechlorinated to cis-1,2-dichloroethene in experiments at 10oC, likely by biological reductive dechlorination. The observed products at 70oC suggest dechlorination catalyzed by reduced sediment iron. Indications of in situ dechlorination were observed in periodic groundwater samples collected during field-scale electrical resistance heating from an average ambient temperature of about 19oC to near boiling. Dechlorination indicators included an increase in chloride concentration at the onset of heating and observation of acetylene, ethene, and methane at elevated temperatures. The data collected in this study suggest that dechlorination can occur during ERH. The overall cost-effectiveness of ERH may be enhanced by fortuitous in situ dechlorination and, potentially, can be further enhanced by specifically designing and operating ERH to maximize in situ dechlorination.

Truex, Michael J.; Powell, Thomas; Lynch, Kira P.

2007-04-01

131

FRACTIONATION OF STABLE CARBON ISOTOPES DURING ABIOTIC TRANSFORMATION OF TCE  

EPA Science Inventory

At a Superfund Site in Minnesota, ground water is contaminated with trichloroethylene (TCE) with the contaminant plume stretching over five miles long. The ground water is iron and manganese reducing, and the complete absence of dichloroethylene, vinyl chloride, and ethene in th...

132

Trichloroethylene (TCE) and toluene effects on the structure and function of the soil community  

Microsoft Academic Search

The effects of trichloroethylene (TCE) and toluene on indigenous soil communities were examined in soil microcosms, with special emphasis on community structure and function. Soil communities were exposed to TCE (1, 30 and 60 ?g ml?1) plus toluene (20 ?g ml?1), TCE only (1, 30 and 60 ?g ml?1), and toluene only (20, 60, 100 and 200 ?g ml?1) (all

Mark E. Fuller; Kate M. Scow; Sean Lau; Howard Ferris

1997-01-01

133

Gas phase trichloroethylene (TCE) photooxidation and byproduct formation: photolysis vs. titania\\/silica based photocatalysis  

Microsoft Academic Search

Photooxidation of trichloroethylene (TCE) was examined in comparative study using photolysis and photocatalysis. Degussa P25 titania coated on reactor wall and deposited on silica based microporous support were used as photocatalyst. The destruction of TCE and formation of potential byproducts were investigated under steady state conditions using annular photoreactors. Experimental work involved passing polluted air containing TCE through the UV

Madjid Mohseni

2005-01-01

134

COMPARISON OF HYDROGEN CONCENTRATIONS IN PCE-DEHALOGENATING AND SULFATE-REDUCING ESTUARINE SEDIMENTS  

EPA Science Inventory

The primary transformation pathway for PCE in anoxic environments is through sequential reductive dehalogenation, and information concerning dehalogenation processes that occur in environments containing alternative electron acceptors (sulfate) is limited. Hydrogen is postulated ...

135

Coupling Surfactants with Permanganate for PCE DNAPL Removal: Coinjection or Sequential Application as Delivery Methods  

Microsoft Academic Search

Batch experiments and two-dimensional (2-D) flow-through cell experiments were conducted to investigate coupling surfactant-enhanced aquifer remediation (SEAR) with in situ chemical oxidation (ISCO) of tetrachloroethene (PCE) dense nonaqueous phase liquid (DNAPL) for PCE mass destruction. Previous batch screening tests were performed on surfactants and cosolvents in the presence of the oxidant potassium permanganate, to assess compatibility for coupling with permanganate.

P. J. Dugan; R. L. Siegrist; M. L. Crimi

2008-01-01

136

Neoantigen formation and clastogenic action of HCFC-123 and perchloroethylene in human MCL-5 cells.  

PubMed

In this study, the metabolic activation of 2,2-dichloro-1,1,1-trifluoroethane (hydrochlorofluorocarbons-123, HCFC-123), halothane or 1,1-dichloro-1-fluoroethane (HCFC-141b) was compared to that of perchloroethylene, using lymphoblastoma derived cell lines expressing human CYP1A1, CYP1A2, CYP2E1, CYP2A6 and CYP3A4 (MCL-5 cells). A dose dependent increase in micronucleus formation was detected over a nominal concentration range of 0.05-2 mM for HCFC-123 and halothane, but this was not seen with HCFC-141b. No dose response for HCFC-123 was seen in a control cHo1 cell line not expressing this cytochrome P450's. Cell lines expressing individual human cytochrome P-450 (CYP) forms were also used to define the enzymes responsible for the clastogenic events and to investigate the formation of immunoreactive protein by microsomal fractions. It was shown that CYP2E1 or CYP2B6 catalysed the clastogenic response, but CYP2D6, CYP3A4, CYP1A2 or CYP1A1 all appeared to be inactive. The formation of neoantigenic trifluoroacetylated protein adducts by microsomal mixtures incubated with HCFC-123 and NADPH was catalysed primarily by CYP2E1 and to a lesser extent by CYP2C19, whereas, only trace levels of immunoreactive protein were seen with microsomes expressing CYP2B6 or CYP2C8. With perchloroethylene as a substrate, the extent of activation was low in comparison with HCFC-123, as judged by the absence of micronuclei formation in the MCL-5 cell line and the weak immunoreactivity of proteins following Western blotting. CYP1A2, CYP2B6 and CYP2C8 appeared to be responsible for perchloroethylene immunoreactivity and in contrast to the findings with the HCFC's, no activation of perchloroethylene by CYP2E1 could be detected. These results show that even though both saturated and unsaturated halocarbons can result in neoantigen formation, there is a marked difference in the specificity of the CYP enzymes involved in their metabolic activation. PMID:11684365

White, I N; Razvi, N; Gibbs, A H; Davies, A M; Manno, M; Zaccaro, C; De Matteis, F; Pähler, A; Dekant, W

2001-10-15

137

Characterization of Microbial Communities in TCE-Contaminated Seep Zone Sediments  

SciTech Connect

Hundreds of sites across the United States contain trichloroethene (TCE) contamination, including the Department of Energy's Savannah River Site (SRS) in Aiken, South Carolina. Previous studies have indicated that microorganisms are capable of efficiently degrading TCE to nonhazardous end products. In this project, molecular and growth based methods were used for microbial characterization of a TCE impacted seepzone where TCE degradation is naturally occurring. The results from this work provide clear evidence that the SRB may play a significant role in TCE degradation along the Twin Lakes seepline.

ROBIN, BRIGMON

2005-03-07

138

Field assessment of carboxymethyl cellulose stabilized iron nanoparticles for in situ destruction of chlorinated solvents in source zones  

Microsoft Academic Search

This study pilot-tested carboxymethyl cellulose (CMC) stabilized zero-valent iron (ZVI) nanoparticles (with a trace amount of Pd catalyst) for in situ destruction of chlorinated ethenes such as perchloroethylene (PCE) and trichloroethylene (TCE) and polychlorinated biphenyls (PCBs) that had been in groundwater for decades. The test site was located in a well-characterized secondary source zone of PCBs and chlorinated ethenes. Four

Feng He; Dongye Zhao; Chris Paul

2010-01-01

139

Well Installation Report for Monitoring Wells TCM4, TCM5, and TCM8 and Pilot Hole TGSC-2A  

Microsoft Academic Search

The shallow groundwater and sediments beneath the TNX Area are contaminated with both dissolved and residual chlorinated volatile organic compounds (CVOCs) such as trichloroethylene (TCE), carbon tetrachloride and perchloroethylene (PCE)..The Savannah River Technology Center (SRTC) is studying a new technology for remediating CVOCs known as GeoSiphon. The GeoSiphon Cell is a large diameter well uses granular cast iron for filter

1998-01-01

140

Enhanced Reductive Dechlorination of TCE in a Basalt Aquifer  

SciTech Connect

A field evaluation of enhanced reductive dechlorination of trichloroethene (TCE) in groundwater has been in progress since November 1998 to determine whether in situ biodegradation can be significantly enhanced through the addition of an electron donor (lactate). An in situ treatment cell was established in the residual source area of a large TCE plume in a fractured basalt aquifer utilizing continuous ground water extraction approximately 150 meters downgradient of the injection location. After a 1-month tracer test and baseline sampling period, the pulsed injection of lactate was begun. Ground water samples were collected from 11 sampling points on a biweekly basis and in situ water quality parameters were recorded every 4 hours at two locations. Within 2 weeks after the initial lactate injection, dissolved oxygen and redox potential were observed to decrease substantially at all sampling locations within 40 m of the injection well. Decreases in nitrate and sulfate concentrations were also observed. Both quantitative in situ rate estimation methods and qualitative measures such as changes in redox conditions, decreases in chlorine number, and changes in biomass indicator parameters are being used throughout the test to evaluate the extent to which biodegradation of TCE is enhanced.

K. S. Sorenson; L. N. Peterson (INEEL); R. Ely (U of Idaho)

1999-04-01

141

A Planet Hunters Search of the Kepler TCE Inventory  

NASA Astrophysics Data System (ADS)

NASA's Kepler spacecraft has spent the past 4 years monitoring ~160,000 stars for the signatures of transiting exoplanets. Planet Hunters (http://www.planethunters.org), part of the Zooniverse (http://www.zooniverse.org) collection of citizen science projects, uses the power of human pattern recognition via the World Wide Web to identify transits in the Kepler public data. We have demonstrated the success of a citizen science approach with the project's discoveries including PH1 b, a transiting circumbinary planet in a four star system., and over 20 previously unknown planet candidates. The Kepler team has released the list of 18,406 potential transit signals or threshold-crossing events (TCEs) identified in Quarters 1-12 (~1000 days) by their automated Transit Planet Search (TPS) algorithm. The majority of these detections found by TPS are triggered by transient events and are not valid planet candidates. To identify planetary candidates from the detected TCEs, a human review of the validation reports, generated by the Kepler pipeline for each TCE, is performed by several Kepler team members. We have undertaken an independent crowd-sourced effort to perform a systematic search of the Kepler Q1-12 TCE list. With the Internet we can obtain multiple assessments of each TCE's data validation report. Planet Hunters volunteers evaluate whether a transit is visible in the Kepler light curve folded on the expected period identified by TPS. We present the first results of this analysis.

Schwamb, Meg; Lintott, Chris; Fischer, Debra; Smith, Arfon; Boyajian, Tabetha; Brewer, John; Giguere, Matt; Lynn, Stuart; Schawinski, Kevin; Simpson, Rob; Wang, Ji

2013-07-01

142

Enhanced Reductive Dechlorination of TCE in a Basalt Aquifer  

SciTech Connect

A field evaluation of enhanced reductive dechlorination of trichloroethene (TCE) in ground water has been in progress since November 1998 to determine whether in situ biodegradation can be significantly enhanced through the addition of an electron donor (lactate). An in situ treatment cell was established in the residual source area of a large TCE plume in a fractured basalt aquifer utilizing continuous ground water extraction approximately 150 meters downgradient of the injection location. After a 1-month tracer test and baseline sampling period, the pulsed injection of lactate was begun. Ground water samples were collected from 11 sampling points on a biweekly basis and in situ water quality parameters were recorded every 4 hours at two locations. Within 2 weeks after the initial lactate injection, dissolved oxygen and redox potential were observed to decrease substantially at all sampling locations within 40 m of the injection well. Decreases in nitrate and sulfate concentrations were also observed. Both quantitative in situ rate estimation methods and qualitative measures such as changes in redox conditions, decreases in chlorine number, and changes in biomass indicator parameters are being used throughout the test to evaluate the extent to which biodegradation of TCE is enhanced.

Sorenson, Kent Soren; Peterson, Lance Nutting; Ely, R. L.

1999-04-01

143

Bacteria associated with oak and ash on a TCE-contaminated site: Characterization of isolates with potential to avoid evapotranspiration of TCE  

SciTech Connect

Along transects under a mixed woodland of English Oak (Quercus robur) and Common Ash (Fraxinus excelsior) growing on a trichloroethylene (TCE)-contaminated groundwater plume, sharp decreases in TCE concentrations were observed, while transects outside the planted area did not show this remarkable decrease. This suggested a possibly active role of the trees and their associated bacteria in the remediation process. Therefore, the cultivable bacterial communities associated with both tree species growing on this TCE-contaminated groundwater plume were investigated in order to assess the possibilities and practical aspects of using these common native tree species and their associated bacteria for phytoremediation. In this study, only the cultivable bacteria were characterized because the final aim was to isolate TCE-degrading, heavy metal resistant bacteria that might be used as traceable inocula to enhance bioremediation. Cultivable bacteria isolated from bulk soil, rhizosphere, root, stem, and leaf were genotypically characterized by amplified rDNA restriction analysis (ARDRA) of their 16S rRNA gene and identified by 16S rRNA gene sequencing. Bacteria that displayed distinct ARDRA patterns were screened for heavy metal resistance, as well as TCE tolerance and degradation, as preparation for possible future in situ inoculation experiments. Furthermore, in situ evapotranspiration measurements were performed to investigate if the degradation capacity of the associated bacteria is enough to prevent TCE evapotranspiration to the air. Between both tree species, the associated populations of cultivable bacteria clearly differed in composition. In English Oak, more species-specific, most likely obligate endophytes were found. The majority of the isolated bacteria showed increased tolerance to TCE, and TCE degradation capacity was observed in some of the strains. However, in situ evapotranspiration measurements revealed that a significant amount of TCE and its metabolites was evaporating through the leaves to the atmosphere. The characterization of the isolates obtained in this study shows that the bacterial community associated with Oak and Ash on a TCE-contaminated site, was strongly enriched with TCE-tolerant strains. However, this was not sufficient to degrade all TCE before it reaches the leaves. A possible strategy to overcome this evapotranspiration to the atmosphere is to enrich the plant-associated TCE-degrading bacteria by in situ inoculation with endophytic strains capable of degrading TCE.

Weyens, N.; van der Lelie, D.; Taghavi, S.; Barac, T.; Boulet, J.; Artois, T.; Carleer, R.; Vangronsveld, J.

2009-11-01

144

A PCE/GMPLS-based collision-avoiding wavelength assignment scheme for WSONs  

NASA Astrophysics Data System (ADS)

In order to solve the wavelength resource reserve collision problem in distributed wavelength assignment senario for PCE/GMPLS-based WSONs, a half-centralized wavelength assignment scheme has been proposed, which efficiently avoids the collision by adding several functions to PCE and doing some extensions to the GMPLS signaling. Simulation results show that the proposed scheme performs much better in decreasing total blocking probability than two traditional ones under various traffic conditions, especially when the traffic load is low while the arrival rate is high.

Xie, Jiuyu; Zhang, Min; Zhang, Lifang; Ji, Yuefeng; Zhang, Jie; Ye, Peida

2010-12-01

145

Review of a draft addendum to the health-assessment document for perchloroethylene. Final report  

SciTech Connect

The Committee previously reviewed a draft Health Assessment Document on May 9-20, 1984 and an Addendum is desirable because of newly available data, primarily an inhalation bioassay of rodents by the National Toxicology Program. The Subcommittee believes it is reasonable to describe the weight of the epidemiological evidence in humans as conforming to the EPA guideline for carcinogen risk-assessment definition of inadequate. The Subcommittee concluded that the animal evidence of carcinogenicity is limited because of positive results in only one strain of mouse of a type of tumor that is common and difficult to interpret. Therefore, the Subcommittee concluded that perchloroethylene belongs in the overall weight-of-the-evidence category C (possible human carcinogen).

Not Available

1987-01-27

146

The enhancement methods for the degradation of TCE by zero-valent metals  

Microsoft Academic Search

Batch tests were performed to compare the degradation rates of TCE on Fe0 and Zn0. Our results indicated that the degradating capability of Zn0 to TCE was nearly 10 times higher than that of Fe0. On the other hand, the degradation rates of Fe0 or Zn0 in conjunction with other metals for reduction of TCE was investigated. The selected metals

Shu-Fen Cheng; Shian-Chee Wu

2000-01-01

147

Pure-Phase Transport and Dissolution of TCE in Sedimentary Rock Saprolite  

Microsoft Academic Search

The objective of this study was to experimentally determine the influence of pore structure on the transport and dissolution of trichloroethylene (TCE) in clay-rich saprolite. In order to simulate a “spill,” pure-phase TCE containing a water-insoluble fluorescent dye was injected into two heterogeneous 24-cm-diameter by 37-cm-long undisturbed columns of water-saturated saprolite. TCE entry occurred at capillary pressures of 2.7 and

M. Lenczewski; Larry McKay; A. Pitner; S. Driese; V. Vulava

2006-01-01

148

The study of lag phase and rate improvement of TCE decay in UV\\/surfactant systems  

Microsoft Academic Search

The photodegradation of trichloroethene (TCE) in surfactant micelles was investigated. The decay of TCE was studied in the Rayonet RPR-200 merry-go-round photoreactor, at 253.7 nm monochromatic ultraviolet (UV) lamps, in the presence of surfactants. Surfactants are used as additional hydrogen sources to improve the photodegradation rates of TCE. About three times the rate increment is observed in the presence of

Wei Chu; Wing-Ki Choy

2000-01-01

149

Removal of gaseous trichloroethylene (TCE) in a composite membrane biofilm reactor  

Microsoft Academic Search

A membrane biofilm reactor (MBfR) was investigated for the degradation of trichloroethylene (TCE) vapors inoculated by Burkholderia vietnamiensis G4. Toluene (TOL) was used as the primary substrate. The MBfR was loaded sequentially with TOL, TCE (or both) during 110 days. In this study, a maximum steady-state TCE removal efficiency of 23% and a maximum volumetric elimination capacity (EC) of 2.1

Amit Kumar; Aline Vercruyssen; Jo Dewulf; Piet Lens; Herman Van Langenhove

2012-01-01

150

Field study of TCE diffusion profiles below DNAPL to assess aquitard integrity  

Microsoft Academic Search

An area where a free-product accumulation of trichloroethylene (TCE) dense non-aqueous phase liquid (DNAPL) occurs at the bottom of a 10-m-thick surficial sand aquifer was studied to determine the integrity of the underlying, 20-m-thick, clayey silt aquitard formed of glaciolacustrine sediment. TCE concentration-versus-depth profiles determined from aquitard cores collected at five locations indicated penetration of detectable TCE 2.5 to 3.0

Beth L. Parker; John A. Cherry; Steven W. Chapman

2004-01-01

151

Transcriptional Expression of the tceA Gene in a Dehalococcoides-Containing Microbial Enrichment  

PubMed Central

Dynamic changes in the transcriptional expression of the tceA gene, which encodes a trichloroethene reductive dehalogenase, were characterized in a Dehalococcoides-containing microbial enrichment culture. Expression was quantified by real-time PCR as the number of tceA transcripts per tceA gene. Expression of tceA increased 40-fold after chlorinated ethene-starved cells were exposed to trichloroethene (TCE), cis-dichloroethene (DCE), or 1,1-DCE but did not increase after exposure to tetrachloroethene or vinyl chloride. Surprisingly, tceA expression also increased 30-fold after cellular exposure to the nonmetabolic substrate trans-DCE, indicating that expression of tceA is induced by both growth-supporting and non-growth-supporting chlorinated ethenes. Additional experiments revealed that the level of tceA expression was independent of the concentration of chlorinated ethenes (sum concentrations of TCE and DCEs of 2.2 to 333 ?M), the concentration of the electron donor hydrogen (concentrations of 12 nM to 17 ?M), and the presence of alternate bacterial electron acceptors (5 mM concentrations of fumarate, sulfate, sulfite, thiosulfate, nitrate, or nitrite) but was highly dependent on incubation temperature.

Johnson, David R.; Lee, Patrick K. H.; Holmes, Victor F.; Fortin, Alexander C.; Alvarez-Cohen, Lisa

2005-01-01

152

Surfactant foam/bioaugmentation technology for in situ treatment of TCE-DNAPLs.  

SciTech Connect

Chlorinated solvents such as trichloroethylene (TCE) are prevalent aquifer contaminants. Depending on the degree of contamination, their physical properties may cause them to occur as dense nonaqueous-phase liquids (DNAPLs) making them difficult to remediate by pump-and-treat methods. Successful in situ bioremediation requires mobilization and dispersion of DNAPLs in order to reduce sediment concentrations to levels nontoxic to degradative bacteria. A bench-scale study was conducted to evaluate a novel remediation technology that utilized surfactant foam for mobilizing and dispersing TCE-DNAPLs combined with a bioaugmentation technology to remediate TCE in situ. Results using the anionic surfactant Steol CS-330 showed that foam injected into TCE-DNAPL-contaminated sand columns enhanced mobilization of TCE-DNAPLs. Mobilization was maximized when the foam was injected in a pulsed operation. Injection of foam followed by artificial groundwater (AGW) and then by foam again resulted in flushing 75% of the initial TCE-DNAPL through an 8-in. column (884 cm3 of sand). The residual TCE was dispersed within the column at concentration levels compatible with biodegradation (<500 {micro}g/g). Adding the TCE-degrading bacterial strain ENV 435 simultaneously with the second pulse of foam resulted in 95-99% degradation of the residual TCE. This level of remediation was achieved with a total of 3 pore volumes (foam/AGW/foam + bacteria) and an aqueous column retention time of 1 h.

Rothmel, R. K.; Peters, R. W.; St. Martin, E.; Deflaun, M. F.; Energy Systems; Envirogen, Inc.

1998-06-01

153

Steam and air co-injection in removing residual TCE in unsaturated layered sandy porous media  

NASA Astrophysics Data System (ADS)

Steam and air co-injection is a promising technique for volatile and semi-volatile organic contaminant remediation in heterogeneous porous media. In this study, removal of trichloroethene (TCE) with steam–air co-injection was investigated through a series of 2D sandbox experiments with different layered sand structures, and through numerical simulations. The results show that a layered structure with coarse sand, in which steam and air convection are relatively rapid, resulted in a higher removal rate and a larger removal ratio than those observed in an experiment using finer sand; however, the difference was not significant, and the removal ratios from three experiments ranged from 85% to 94%. Slight downward movement of TCE was observed for Experiment 1 (TCE initially in a fine sand zone encased in a coarse sand), while no such movement was observed for Experiment 2 (TCE initially in two fine sand layers encased in a coarse sand) or 3 (TCE initially in a silty sand zone encased in a coarse sand). Simulations show accumulation of TCE at the interface of the layered sands, which indicates a capillary barrier effect in restraining the downward movement of TCE. This effect is illustrated further by a numerical experiment with homogeneous coarse sand, in which continuous downward TCE movement to the bottom of the sandbox was simulated. Another numerical experiment with higher water saturation was also conducted. The results illustrate a complicated influence of water saturation on TCE removal in a layered sand structure.

Peng, Sheng; Wang, Ning; Chen, Jiajun

2013-10-01

154

Steam and air co-injection in removing residual TCE in unsaturated layered sandy porous media.  

PubMed

Steam and air co-injection is a promising technique for volatile and semi-volatile organic contaminant remediation in heterogeneous porous media. In this study, removal of trichloroethene (TCE) with steam-air co-injection was investigated through a series of 2D sandbox experiments with different layered sand structures, and through numerical simulations. The results show that a layered structure with coarse sand, in which steam and air convection are relatively rapid, resulted in a higher removal rate and a larger removal ratio than those observed in an experiment using finer sand; however, the difference was not significant, and the removal ratios from three experiments ranged from 85% to 94%. Slight downward movement of TCE was observed for Experiment 1 (TCE initially in a fine sand zone encased in a coarse sand), while no such movement was observed for Experiment 2 (TCE initially in two fine sand layers encased in a coarse sand) or 3 (TCE initially in a silty sand zone encased in a coarse sand). Simulations show accumulation of TCE at the interface of the layered sands, which indicates a capillary barrier effect in restraining the downward movement of TCE. This effect is illustrated further by a numerical experiment with homogeneous coarse sand, in which continuous downward TCE movement to the bottom of the sandbox was simulated. Another numerical experiment with higher water saturation was also conducted. The results illustrate a complicated influence of water saturation on TCE removal in a layered sand structure. PMID:23962760

Peng, Sheng; Wang, Ning; Chen, Jiajun

2013-07-16

155

Effect of inorganic ions in heterogeneous photocatalysis of TCE  

Microsoft Academic Search

The influence of 12 ionic compounds (NaâSOâ, NaHCOâ, NaâHPOâ, NaNOâ, NaCl, MnClâ, NiClâ, CaClâ, MgClâ, AlClâ, FeClâ, and MgSOâ) on performance of a fixed-bed photocatalytic reactor is examined. The fixed-bed photocatalyst was developed at Michigan Technological University and comprises 1% Pt-TiOâ on a silica-based support. The degradation of trichloroethylene (TCE) in Milli-Q water is used to monitor catalyst performance. All

Robert A. Burns; John C. Crittenden; David W. Hand; Volker H. Selzer; Lawrence L. Sutter; Salman R. Salman

1999-01-01

156

DEPENDENCE OF A HIGH-RATE, PCE-DECHLORINATING ENRICHMENT CULTURE ON METHANOGENIC ACTIVITY. (R825549C053)  

EPA Science Inventory

The role served by the presence of methanogenic activity within a tetrachloroethene (PCE)-dechlorinating culture was investigated through a series of supplementation experiments. An acclimated lactate-enrichment culture (LEC 1) capable of rapidly converting PCE to ethene was s...

157

The Impact of Composition on the Physical Properties and Evaporative Mass Transfer of a PCE-Diesel Immiscible Liquid  

PubMed Central

The impact of immiscible-liquid composition on mass transfer between immiscible liquid and vapor was evaluated for a complex mixture of chlorinated solvents and petroleum hydrocarbons. A mixture of PCE (tetrachloroethene) and diesel was discovered at a site in Tucson, Arizona. Partitioning of PCE into a previously spilled diesel free product has been observed, with resultant concentrations of PCE above 15% by weight. The density, viscosity, surface tension, and interfacial tension were measured for PCE-diesel mixtures with PCE fractions from 7 to 32%, and the results indicated that immiscible-liquid composition did impact the physical properties of the PCE-diesel mixture. Comparison of gas and aqueous phase partitioning results to predictions based on Raoult's Law indicated that the immiscible liquid behaved essentially as an ideal mixture. Flow-cell experiments were conducted to characterize PCE removal from the PCE-diesel mixture via vapor extraction. The effluent concentrations for the experiment conducted with free-phase immiscible liquid were comparable to equilibrium values. Conversely, they were significantly lower for the experiment wherein a residual saturation of immiscible liquid was distributed within sand. These results suggest that evaporation for the latter experiment was constrained by rate-limited mass transfer, which was attributed to dilution effects associated with a nonuniform immiscible-liquid distribution.

Carroll, Kenneth C.; Taylor, Renee; Gray, Evan; Brusseau, Mark L.

2010-01-01

158

Adult neuropsychological performance following prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water.  

PubMed

This population-based retrospective cohort study examined adult performance on a battery of neuropsychological tests in relation to prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using pipe network information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling software, and a Geographic Information System (GIS). Results of crude and multivariate analyses among 35 exposed and 28 unexposed subjects showed no association between prenatal and early postnatal exposure and decrements on tests that assess abilities in the domains of omnibus intelligence, academic achievement or language. The results were suggestive of an association between prenatal and early postnatal PCE exposure and diminished performance on tests that assessed abilities in the domains of visuospatial functioning, learning and memory, motor, attention and mood. Because the sample size was small, most findings were not statistically significant. Future studies with larger sample sizes should be conducted to further define the neuropsychological consequences of early developmental PCE exposure. PMID:22522125

Janulewicz, Patricia A; White, Roberta F; Martin, Brett M; Winter, Michael R; Weinberg, Janice M; Vieira, Veronica; Aschengrau, Ann

2012-04-12

159

Reductive dechlorination of TCE by zero valent bimetals.  

PubMed

Six zero valent bimetal combinations were tested for trichloroethene (TCE) dechlorination. Palladium, nickel, and copper were coated at 500 mg kg(-1) or less onto zero valent iron, producing Pd/Fe, Ni/Fe, and Cu/Fe bimetals, and zinc, producing Pd/Zn, Ni/Zn, and Cu/Zn bimetals. The order of reactivity of the six bimetals and two metals based on surface area normalized pseudo first order rate constants was observed to be: Pd/Fe > Pd/Zn > Ni/Fe > Cu/Fe > Ni/Zn > Cu/Zn > Fe > Zn. Thus, in general, 1) iron metal and bimetals exhibit faster reaction rates than the corresponding zinc reductants, 2) bimetals exhibit faster reaction rates than pure metals, and 3) metal coating enhance reactivity in the order of Pd > Ni > Cu. Chlorinated intermediate products were observed in small amounts for Fe only. In all cases, the chloride balance, calculated from TCE and chloride concentrations, ranged from 90 to 111%. The results are discussed in terms of the effects of bimetal combinations on catalytic dechlorination, prevention of nonreactive film and metal corrosion. PMID:12641254

Kim, Y H; Carraway, E R

2003-01-01

160

Degradation of TCE with iron: The role of competing chromate and nitrate reduction  

Microsoft Academic Search

This study evaluates the potential of using granular iron metal for the abiotic removal of the organic ground water pollutant trichloroethene (TCE) in the presence of the common inorganic co-contaminants chromate and nitrate, respectively. Their long-term column experiments indicate a competitive process between TCE dechlorination and reductive transformation of chromate and nitrate, which is reflected in a significantly delayed onset

Oliver Schlicker; Markus Ebert; Margit Fruth; Markus Weidner; W. Wuest; Andreas Dahmke

2000-01-01

161

Laboratory column studies for evaluating a barrier system for providing oxygen and substrate for TCE biodegradation  

Microsoft Academic Search

The industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination. The objective of this study was to develop a biobarrier system containing oxygen–organic releasing material to enhance the aerobic cometabolism of TCE in situ. The oxygen–organic material, which contains calcium peroxide and peat, is able to release oxygen and primary substrates continuously upon contact

C. M. Kao; S. C. Chen; M. C. Su

2001-01-01

162

RATE OF TCE DEGRADATION IN PASSIVE REACTIVE BARRIERS CONSTRUCTED WITH PLANT MULCH (BIOWALLS)  

EPA Science Inventory

This presentation reviews a case study at Altus AFB on the extent of treatment of TCE in a passive reactive barrier constructed with plant mulch. It presents data from a tracer test to estimate the rate of ground water flow at the site, and the residence time of water and TCE in...

163

MICROFRACTURE SURFACE GEOCHEMISTRY AND ADHERENT MICROBIAL POPULATION METABOLISM IN TCE-CONTAMINATED COMPETENT BEDROCK  

EPA Science Inventory

A TCE-contaminated competent bedrock site in Portsmouth, NH was used to determine if a relation existed between microfracture (MF) surface geochemistry and the ecology and metabolic activity of attached microbes relative to terminal electron accepting processes (TEAPs) and TCE bi...

164

[Effects of soil and ground water pollution with perchloroethylene from the public health service viewpoint].  

PubMed

A routine analysis of drinking water conducted in September 1987 in a Rhenish water works revealed a perchloroethylene (PER) content of 3 micrograms/l. Within less than 3 months the concentration in the two northern wells of the entire battery consisting of 4 wells rose to 20 micrograms/l, and hence the complete battery had to be shut off from the water supply network. The pumped-up water was diverted to a draining plant via the precipitation tank of the water works. During the two subsequent months the PER concentration continued to rise, especially in well No. 1, to more than 120 micrograms/l. The present report deals with the measures undertaken to assess the extent of the damage and the effects of the incident on drinking water supply, on the storage of foods in a warehouse, on a planned sewer construction and on the systems installed by various parties for their own water supply, and on wells in private gardens and in a gardening nursery. PMID:2143281

Hauswirth, S

1990-07-01

165

Experimental Results on the Destruction of PCE using a Photo-Chemical Remediation Reactor  

NASA Astrophysics Data System (ADS)

A vapor-phase tetrachloroethylene (PCE) destruction experiment using a newly constructed photo-chemical remediation (PCR) reactor is performed. One of the applications for the PCR reactor is subsurface remediation of volatile organic compounds (VOCs). Ultraviolet (UV) light, when emitted at an effective absorption frequency (primary wavelengths of 185 and 254 nm), cleaves a VOC's carbon-chlorine bond thus reducing harmful contaminants to harmless products. The PCR reactor consists of a stainless steel tubular vessel with internal dimensions 0.32 m in diameter and 1.05 m in length. Sixteen Suprasil glass sleeves (Heraeus Inc.) with external dimensions of 25 mm in diameter and 1.1 m in length are inserted along the length of the reactor. The Suprasil sleeves are positioned in a geometrical pattern to provide maximum UV exposure. An amalgam UV lamp (Heraeus Inc. NIQ 200/110) is placed inside every Suprasil sleeve. Each UV lamp has its own igniter and ballast for versatile power control. The Suprasil sleeves provide barrier protection between the UV lamps and the vapor-phase contaminant, and at the same time allow transmission of UV light to the interior of the PCR reactor. A gas heater is installed to increase the influent vapor-phase temperature and the PCR reactor is insulated to minimize heat loss. However, the PCE destruction experiment is presently being performed without the aid of the gas heater. During the experiment, the PCR reactor temperature reached in excess of 200 degrees Celsius from heat generated from the UV lamps. Vapor-phase samples are collected at the influent and effluent reactor sampling ports prior and after UV lamp ignitions. Preliminary results show good PCE destruction efficiency for the range of influent PCE concentrations considered in this study.

Lee, J. J.; Lee, K. Y.; Stencel, J. R.; Khinast, J.

2001-12-01

166

Experimental Results on the Destruction of PCE using a PhotoChemical Remediation Reactor  

Microsoft Academic Search

A vapor-phase tetrachloroethylene (PCE) destruction experiment using a newly constructed photo-chemical remediation (PCR) reactor is performed. One of the applications for the PCR reactor is subsurface remediation of volatile organic compounds (VOCs). Ultraviolet (UV) light, when emitted at an effective absorption frequency (primary wavelengths of 185 and 254 nm), cleaves a VOC's carbon-chlorine bond thus reducing harmful contaminants to harmless

J. J. Lee; K. Y. Lee; J. R. Stencel; J. Khinast

2001-01-01

167

A risk-based cleanup criterion for PCE in soil. [Tetrachloroethylene  

SciTech Connect

The most important attribute of a chemical contaminant at a hazardous-wastes site for decision makers to consider with regard to its cleanup is the potential risk associated with human exposure. For this reason we have developed a strategy for establishing a risk-based cleanup criterion for chemicals in soil. We describe this strategy by presenting a cleanup criterion for tetrachloroethylene (PCE) in soil associated with a representative California landscape. We being by discussing the environmental fate and transport model, developed at the Lawrence Livermore National Laboratory (LLNL), that we used to predict the equilibrium concentration of PCE in five environmental media from a steady-state source in soil. Next, we explain the concept and application of pathway-exposure factors (PEFs), the hazard index, and cancer-potency factors (CPFs) for translating the predicted concentrations of PCE into estimated potential hazard or risk for hypothetically exposed individuals. Finally, the relationship between concentration and an allowable level of risk is defined and the societal and financial implications are discussed. 22 refs., 6 tabs.

Daniels, J.I.; McKone, T.E.; Hall, L.C.

1990-09-26

168

Use of emulsified vegetable oil to support bioremediation of TCE DNAPL in soil columns.  

PubMed

The interaction between emulsified vegetable oil (EVO) and trichloroethylene (TCE) dense non-aqueous phase liquid (DNAPL) was observed using two soil columns and subsequent reductive dechlorination of TCE was monitored over a three year period. Dyed TCE DNAPL (~75 g) was emplaced in one column (DNAPL column), while the second was DNAPL-free (plume column). EVO was added to both columns and partitioning of the EVO into the TCE DNAPL was measured and quantified. TCE (1.9 mM) was added to the influent of the plume column to simulate conditions down gradient of a DNAPL source area and the columns were operated independently for more than one year, after which they were connected in series. Initially limited dechlorination of TCE to cDCE was observed in the DNAPL column, while the plume column supported complete reductive dechlorination of TCE to ethene. Upon connection and reamendment of the plume column with EVO, near saturation levels of TCE from the effluent of the DNAPL column were rapidly dechlorinated to c-DCE and VC in the plume column; however, this high rate dechlorination produced hydrochloric acid which overwhelmed the buffering capacity of the system and caused the pH to drop below 6.0. Dechlorination efficiency in the columns subsequently deteriorated, as measured by the chloride production and Dehalococcoides counts, but was restored by adding sodium bicarbonate buffer to the influent groundwater. Robust dechlorination was eventually observed in the DNAPL column, such that the TCE DNAPL was largely removed by the end of the study. Partitioning of the EVO into the DNAPL provided significant operational benefits to the remediation system both in terms of electron donor placement and longevity. PMID:23697993

Harkness, Mark; Fisher, Angela

2013-04-15

169

Structure, inheritance, and transcriptional effects of Pce1, an insertional element within Phanerochaete chrysosporium lignin peroxidase gene lipI  

SciTech Connect

A 1747-bp insertion within a lignin peroxidase allele of Phanerochaete chrysosporium BKM-F-1767 is described. Pce1, the element, lies immediately adjacent to the fourth intron of lipI2. Southern blots reveal the presence of Pce1-homologous sequences in other P. chrysosporium strains. Transposon-like features include inverted terminal repeats and a dinucleotide (TA) target duplication. Atypical of transposons, Pce1 is present at very low copy numbers (one to five copies), and conserved transposase motifs are lacking. The mutation transcriptionally inactivates lipI2 and is inherited in a 1:1 Mendelian fashion among haploid progeny. Thus, Pce1 is a transposon-like element that may play a significant role in generating ligninolytic variation in certain P. chrysosporium strains. 39 refs., 7 figs.

Gaskell, J. [Department of Agriculture, Madison, WI (United States); Wymelenberg, A.V. [Univ. of Wisconsin, Madison, WI (United States); Cullen, D. [U.S. Department of Agriculture, Madison, WI (United States)]|[Univ. of Wisconsin, Madison, WI (United States)

1995-08-01

170

76 FR 13182 - Settlement Agreement for Recovery of Past Response Costs; 345 North 700 East, Richfield PCE Site...  

Federal Register 2010, 2011, 2012, 2013

...9606(a), 9607, and 9622, between the United States Environmental Protection Agency (EPA) and Jerry Thomas and Katrina Thomas (Settling Parties) regarding the Richfield PCE Site (Site), located at 345 North 700 East,...

2011-03-10

171

Solubilities of Toluene, Benzene and TCE in High-Biomass Systems  

SciTech Connect

We report measurements of solubility limits for benzene, toluene, and TCE in systems that contain varying levels of biomass up to 0.13 g/mL. The solubility limit increased from 20 to 48 mM when biomass (in the form of yeast) was added to aqueous batch systems containing benzene. The toluene solubility limit increased from 4.9 to greater than 20 mM. For TCE, the solubility increased from 8 mM to more than 1000 mM. Solubility for TCE was most heavily impacted by biomass levels, changing by two orders of magnitude.

Barton, John W. [Battelle Eastern Science & Technology Center; Vodraska, Christopher D [ORNL; Flanary, Sandie A. [Oak Ridge National Laboratory (ORNL); Davison, Brian H [ORNL

2008-01-01

172

Laboratory evaluation of a two-stage treatment system for TCE cometabolism by a methane-oxidizing mixed culture  

SciTech Connect

The objective of this research was to evaluate several factors affecting the performance of a two-stage treatment system employing methane-oxidizing bacteria for trichloroethylene (TCE) biodegradation. The system consists of a completely mixed growth reactor and a plug-flow transformation reactor in which the TCE is cometabolized. Laboratory studies were conducted with continuous growth reactors and batch experiments simulating transformation reactor conditions. Performance was characterized in terms of TCE transformation capacity (T{sub C}, g TCE/g cells), transformation yield (T{sub Y}, g TCE/g CH{sub 4}), and the rate coefficient ratio k{sub TCE}/K{sub S,TCE} (L/mg-d). The growth reactor variables studied were solids retention time (SRT) and nutrient nitrogen (N) concentration. Formate and methane were evaluated as potential transformation reactor amendments.

Smith, L.H. [Massey Univ., Palmerston North (New Zealand). Dept. of Process and Environmental Technology; McCarty, P.L. [Stanford Univ., CA (United States). Dept. of Civil Engineering

1997-08-20

173

TCE Flagship Technical Paper: Data for Validaton of Human PBPK Model.  

National Technical Information Service (NTIS)

The Armstrong Laboratory Occupational and Environmental Health Directorate, Toxicology Division is supporting the current flagship review of the environmental risks of trichloroethylene (TCE) being conducted by the U.S. Environmental Protection Agency (EP...

E. A. Merrill T. R. Sterner L. A. May

1997-01-01

174

In situ detection of organic molecules: Optrodes for TCE and CHCl(sub 3).  

National Technical Information Service (NTIS)

We have developed new absorption-based chemical indicators for detecting chloroform (CHCl(sub 3)) and trichloroethylene (TCE). These indicators were used to make very sensitive optical chemical sensors (optrodes) for each of these two contaminants. Concen...

S. M. Angel K. C. Langry M. N. Ridley

1990-01-01

175

IDENTIFICATION OF CHLOROMETHANE FORMATION PATHS DURING ELECTROCHEMICAL DECHLORINATION OF TCE USING GRAPHITE ELECTRODES  

EPA Science Inventory

The purpose of this research is to investigate the formation of chloromethane during TCE dechlorination in a mixed electrochemical reactor using graphite electrodes. Chloromethane was the major chlorinated organic compound detected in previous dechlorination experiments. In order...

176

IDENTIFICATION OF CHLOROMETHANE FROMATION PATHS DURING ELECTROCHEMICAL DECHLORINATION OF TCE USING GRAPHITE ELECTRODES  

EPA Science Inventory

The purpose of this research is to investigate the formation of chloromethane during TCE dechlorination in a mixed electrochemical reactor using graphite electrodes. Chloromethane was the major chlorinated organic compound detected in previous dechlorination experiments. In order...

177

UNCERTAINTY ANALYSIS OF TCE USING THE DOSE EXPOSURE ESTIMATING MODEL (DEEM) IN ACSL  

EPA Science Inventory

The ACSL-based Dose Exposure Estimating Model(DEEM) under development by EPA is used to perform art uncertainty analysis of a physiologically based pharmacokinetic (PSPK) model of trichloroethylene (TCE). This model involves several circulating metabolites such as trichloroacet...

178

In-situ bioremediation of TCE-contaminated groundwater  

SciTech Connect

This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). A barrier to wider use of in situ bioremediation technology is that results are often variable and difficult to predict. In situ bioremediation has shown some very notable and well publicized successes, but implementation of the technology is complex. An incomplete understanding of the effects of variable site characteristics and the lack of adequate tools to predict and measure success have made the design, control and validation of bioremediation more empirical than desired. The long-term objective of this project is to improve computational tools used to assess and optimize the expected performance of bioremediation at a site. An important component of the approach is the explicit inclusion of uncertainties and their effect on the end result. The authors have extended their biokinetics model to include microbial competition and predation processes. Predator species can feed on the microbial species that degrade contaminants, and the simulation studies show that species interactions must be considered when designing in situ bioremediation systems. In particular, the results for TCE indicate that protozoan grazing could reduce the amount of biodegradation by about 20%. These studies also indicate that the behavior of barrier systems can become complex due to predator grazing.

Travis, B.J. [Los Alamos National Lab., NM (United States); Rosenberg, N.D. [Lawrence Livermore National Lab., CA (United States)

1998-12-31

179

Effect of inorganic ions in heterogeneous photocatalysis of TCE  

SciTech Connect

The influence of 12 ionic compounds (Na{sub 2}SO{sub 4}, NaHCO{sub 3}, Na{sub 2}HPO{sub 4}, NaNO{sub 3}, NaCl, MnCl{sub 2}, NiCl{sub 2}, CaCl{sub 2}, MgCl{sub 2}, AlCl{sub 3}, FeCl{sub 3}, and MgSO{sub 4}) on performance of a fixed-bed photocatalytic reactor is examined. The fixed-bed photocatalyst was developed at Michigan Technological University and comprises 1% Pt-TiO{sub 2} on a silica-based support. The degradation of trichloroethylene (TCE) in Milli-Q water is used to monitor catalyst performance. All compounds are found to inhibit photocatalysis at some or all of the concentrations tested, although only MnCl{sub 2} seems to suppress it altogether. Fouling appears to be a least partially reversible. Electron microprobe analysis is employed to investigate how selected fouling agents interact with the catalyst and support.

Burns, R.A.; Crittenden, J.C.; Hand, D.W.; Selzer, V.H.; Sutter, L.L. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Civil and Environmental Engineering; Salman, S.R. [Yarmouk Univ., Irbid (Jordan). Dept. of Chemistry

1999-01-01

180

Remediation of TCE contaminated soils by in situ EK-Fenton process  

Microsoft Academic Search

The treatment performance and cost analysis of in situ electrokinetic (EK)-Fenton process for oxidation of trichloroethylene (TCE) in soils were evaluated in this work. In all experiments, an electric gradient of 1V\\/cm, de-ionized water as the cathode reservoir fluid and a treatment time of 10 days were employed. Treatment efficiencies of TCE were evaluated in terms of the electrode material,

Gordon C. C. Yang; Chyi-Yech Liu

2001-01-01

181

Degradation of phenol and TCE using suspended and chitosan-bead immobilized Pseudomonas putida  

Microsoft Academic Search

The degradability of phenol and trichloroethene (TCE) by Pseudomonas putida BCRC 14349 in both suspended culture and immobilized culture systems are investigated. Chitosan beads at a size of about 1–2mm were employed to encapsulate the P. putida cells, becoming an immobilized culture system. The phenol concentration was controlled at 100mg\\/L, and that of TCE was studied from 0.2 to 20mg\\/L.

Yan-Min Chen; Tsair-Fuh Lin; Chih Huang; Jui-Che Lin; Feng-Ming Hsieh

2007-01-01

182

Anaerobic dechlorination of trichloroethylene (TCE) to ethylene using complex organic materials  

Microsoft Academic Search

Reductive dechlorination of trichloroethylene (TCE) to ethylene was supported by complex organic matter such as cane molasses and ligno-cellulosic materials as a substrate and electron donor under methanogenic conditions. The studies were performed with an anaerobic dechlorinating, methanogenic microbial consortium at 20–22°C. A high molar ratio between methane and ethylene (158mol\\/mol) was observed during rapid dechlorination of TCE with cane

Wei-Min Wu; Jeffery Nye; Mahendra K. Jain; Robert F. Hickey

1998-01-01

183

Correlation of TCE cometabolism with growth characteristics on aromatic substrates in toluene-degrading bacteria  

Microsoft Academic Search

We have constructed a bacterial library consisting of 97 strains of toluene-degrading bacteria from soil and activated sludge samples for examining their physiological properties in terms of cometabolism of TCE. Large variation of TCE degradation ability was observed in Gram-positive and Gram-negative strains, as well as diverse patterns of availability of aromatics as a growth substrate. No clear correlation was

Yuki Morono; Hajime Unno; Katsutoshi Hori

2006-01-01

184

Effects of hydrogeological characteristics on the attenuation of TCE- contaminated groundwater plume in Wonju, Korea  

NASA Astrophysics Data System (ADS)

Key attributes to temporal and seasonal variation of TCE and its daughter products at an industrial complex, Wonju, Korea were evaluated using groundwater monitoring data along with data from field investigations. The purpose of this study is to analyze the hydrogeological characteristics and seasonal variations associated with the plume attenuation of TCE and its daughter products. Study site is underlain by Jurassic biotite granite which is covered by quarternary alluvium. Average hydraulic conductivities of alluvial layer and bed rock are 2.4*10-3 and 2.0*10-4 cm/sec, respectively. The alluvial layer acts as a main layer for TCE contaminated groundwater flow. Average annual rainfall in this study area is 1,414 mm/year and over 65% of annual precipitation is concentrated in July, August and September. Seasonal variation of TCE contaminant plume shape near the source area and downgradient area are different depending on the surface recharge characteristics. The downgradient area is not much affected by seasonal rainfalls, but TCE contaminant concentration in the source area is greatly affected by the seasonal rainfalls. The water table fluctuation at the source area was maximally 1.95 m but the downgradient at industrial complex area was 0.9 m during concentrated rainfall events. General tendency of TCE contaminant concentrations at source zone was highly fluctuated and temporally increased due to rainfall events. As a result, due to the limited recharge and time-lag of the impact of precipitation in summer season, the TCE contaminant plume distribution and the impact of seasonal effect diminish as the distance from the source area increases. Keywords : TCE, recharge, precipitation, plume attenuation, seasonal variation

Lee, H.; Yang, J.; Lee, K.

2010-12-01

185

Assessing TCE source bioremediation by geostatistical analysis of a flux fence.  

PubMed

Mass discharge across transect planes is increasingly used as a metric for performance assessment of in situ groundwater remediation systems. Mass discharge estimates using concentrations measured in multilevel transects are often made by assuming a uniform flow field, and uncertainty contributions from spatial concentration and flow field variability are often overlooked. We extend our recently developed geostatistical approach to estimate mass discharge using transect data of concentration and hydraulic conductivity, so accounting for the spatial variability of both datasets. The magnitude and uncertainty of mass discharge were quantified by conditional simulation. An important benefit of the approach is that uncertainty is quantified as an integral part of the mass discharge estimate. We use this approach for performance assessment of a bioremediation experiment of a trichloroethene (TCE) source zone. Analyses of dissolved parent and daughter compounds demonstrated that the engineered bioremediation has elevated the degradation rate of TCE, resulting in a two-thirds reduction in the TCE mass discharge from the source zone. The biologically enhanced dissolution of TCE was not significant (~5%), and was less than expected. However, the discharges of the daughter products cis-1,2, dichloroethene (cDCE) and vinyl chloride (VC) increased, probably because of the rapid transformation of TCE from the source zone to the measurement transect. This suggests that enhancing the biodegradation of cDCE and VC will be crucial to successful engineered bioremediation of TCE source zones. PMID:22352471

Cai, Zuansi; Wilson, Ryan D; Lerner, David N

2012-02-21

186

Effects of a nutrient-surfactant compound on solubilization rates of TCE  

SciTech Connect

BioTreat{trademark}, a commercially available nutrient-surfactant compound, was investigated for its ability to solubilize TCE. Potential mechanisms for enhancing biodegradation rates by the use of nutrient-surfactant mixtures are: increased solubilization of TCE into the aqueous phase, and increased nutrients for the bacteria and greater numbers of colony forming units (CFUs). In aqueous systems, no measured solubilization of 0.1 and 1.0 ppm TCE from the headspace into the liquid phase was observed with BioTreat added at concentrations <0.5%. However, at BioTreat concentrations in excess of the CMC (>0.5%), increased solubilization of TCE was measured. A second question was the nutrient effect of BioTreat on the growth of the TCE-degrading bacterium, Burkholderia cepacia G4 PR1{sub 301}. The added nutrients provided by BioTreat was evident and lead to increased cell numbers. The effect of BioTreat on the expression of ortho-monooxgenase, the enzyme necessary for TCE degradation by B. cepacia was also investigated. Enzyme expression as detected by a calorimetric assay was inhibited for BioTreat concentrations >0.05%. 17 refs., 5 figs., 3 tabs.

Gillespie, M.T.; Strong-Gunderson, J.M. [Oak Ridge National Lab., TN (United States)

1997-12-31

187

Endophytic bacteria improve phytoremediation of Ni and TCE co-contamination  

SciTech Connect

The aim of this work was to investigate if engineered endophytes can improve phytoremediation of co-contaminations by organic pollutants and toxic metals. As a model system, yellow lupine was inoculated with the endophyte Burkholderia cepacia VM1468 possessing (a) the pTOM-Bu61 plasmid, coding for constitutive trichloroethylene (TCE) degradation, and (b) the ncc-nre Ni resistance/sequestration system. Plants were exposed to Ni and TCE and (a) Ni and TCE phytotoxicity, (b) TCE degradation and evapotranspiration, and (c) Ni concentrations in the roots and shoots were determined. Inoculation with B. cepacia VM1468 resulted in decreased Ni and TCE phytotoxicity, as measured by 30% increased root biomass and up to 50% decreased activities of enzymes involved in anti-oxidative defence in the roots. In addition, TCE evapotranspiration showed a decreasing trend and a 5 times higher Ni uptake was observed after inoculation. Engineered endophytes can improve phytoremediation of mixed contaminations via enhanced degradation of organic contaminants and improved metal uptake and translocation.

Weyens, N.; van der Lelie, D.; Croes, S.; Dupae, J.; Newman, L.; Carleer, R.; Vangronsveld, J.

2010-07-01

188

Microbial enhancement of TCE and 1,2-DCA solute flux in UF-membrane bioreactors  

SciTech Connect

An ultrafiltration membrane process was used to remove and biograde chlorinated aliphatic hydrocarbons trichloroethylene (TCE) and 1,2-dichloroethane (1,2-DCA) from dilute aqueous streams. The effect of microbial biodegradative activity on TCE and 1,2-DCA solute flux in a polypropylene membrane was examined using microbial strains Pseudomonas cepacia PRI{sub 31} for the biodegradation of TCE and Xanthobacter autotrophicus GJ10 for the biodegradation of 1,2-DCA. Initial experiments were conducted in diaphragm cells in the absence of microorganisms to determine the diffusion coefficient of 1,2-DCA and TCE in the polypropylene ultrafiltration (UF) membranes. The diffusivities were 4.7 {times} 10{sup {minus}8} cm{sup 2}/s for 1,2-DCA and 1.41 {times} 10{sup {minus}7} cm{sup 2}/s for TCE. Subsequent experiments were conducted with microorganisms on the permeate side to examine the effect of microbial degradation of 1,2-DCA and TCE on the solute flux across the UF membrane. Experiments were conducted sequentially in batch and flow diaphragm cells and then in a hollow-fiber UF module to systematically examine the effect of microbial activity on the solute flux in each configuration and the ability of mathematical models to predict the microbial enhancement of solute flux. Microbial biodegradation of TCE and 1,2-DCA significantly enhanced the solute flux, and experimental results were correlated with steady- and nonsteady-state solute component balance models for the flow and batch diaphragm cells, respectively. Model and experimental results agree well. Implications for using membrane bioreactors to treat CAH contaminated groundwater and industrial effluents are discussed.

Inguva, S.; Boensch, M.; Shreve, G.S. [Wayne State Univ., Detroit, MI (United States). Dept. of Chemical Engineering and Materials Science

1998-09-01

189

Degradation of TCE with iron: The role of competing chromate and nitrate reduction  

SciTech Connect

This study evaluates the potential of using granular iron metal for the abiotic removal of the organic ground water pollutant trichloroethene (TCE) in the presence of the common inorganic co-contaminants chromate and nitrate, respectively. Their long-term column experiments indicate a competitive process between TCE dechlorination and reductive transformation of chromate and nitrate, which is reflected in a significantly delayed onset of TCE dechlorination. Delay times and therefore the ranges of the nonreactive flowpaths increased with increasing experimental duration, resulting in a migration of the contaminants through the iron metal treatment zone. The present investigation also indicates that the calculated migration rates of TCE and the added cocontaminants chromate and nitrate are linearly related to the initial content of the cocontaminants. With an average pore water velocity of 0.6 m/d and a surface area concentration of 0.55 m{sup 2}/mL in the column, the calculated migration rates varied between 0.10 cm/d and 5.86 cm/d. The particular similarity between the values of TCE migration and the migration of the strong oxidants chromate and nitrate and the long-term steady state of the TCE dechlorination in the absence of the chromate and nitrate indicates that these competitive transformations are the driving force for the gradual passivation of the granular iron due to the buildup of an electrically insulating Fe(III)-oxyhydroxide. Based on these passivation processes, general formulae were developed that allow a simplified approximation of breakthrough times for the contaminants TCE, chromate, and nitrate.

Schlicker, O.; Ebert, M.; Fruth, M.; Weidner, M.; Wuest, W.; Dahmke, A.

2000-06-01

190

Microbial community changes associated with a shift from reductive dechlorination of PCE to reductive dechlorination of cis-DCE and VC  

SciTech Connect

Subcultures that reductively dechlorinate cis-dichloroethene (cis-DCE) or vinyl chloride (VC) were derived from three independent enrichments that completely dechlorinated tetrachloroethene (PCE) to ethene in order to study the reductive dechlorination of the lesser chlorinated ethenes. These subcultures completely dechlorinated cis-DCE and VC and could be transferred indefinitely in basal salts minimal medium with H{sub 2} as the electron donor. After 10 transfers (1% V/V) the cis-DCE and VC-dechlorinating subcultures from two of the PCE enrichments failed to dechlorinate PCE, but the subcultures from the third PCE enrichment maintained the ability to dechlorinate PCE. Analysis of the 16S rRNA genes from these enrichments by terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE) demonstrated shifts in the community composition of the subcultures that had lost the PCE-dechlorinating activity but not in the subcultures that maintained the PCE-dechlorinating activity. Analysis of the changes in community composition of the different enrichments suggested that at least two populations were responsible for the sequential dechlorination of PCE to ethene in these cultures and that consortia can cooperate in the complete dechlorination of PCE.

Flynn, S.J.; Loeffler, F.E.; Tiedje, J.M.

2000-03-15

191

Numerical simulation of transport and sequential biodegradation of chlorinated aliphatic hydrocarbons using CHAIN_2D  

NASA Astrophysics Data System (ADS)

Microbiological degradation of perchloroethylene (PCE) under anaerobic conditions follows a series of chain reactions, in which, sequentially, trichloroethylene (TCE), cis-dichloroethylene (c-DCE), vinylchloride (VC) and ethene are generated. First-order degradation rate constants, partitioning coefficients and mass exchange rates for PCE, TCE, c-DCE and VC were compiled from the literature. The parameters were used in a case study of pump-and-treat remediation of a PCE-contaminated site near Tilburg, The Netherlands. Transport, non-equilibrium sorption and biodegradation chain processes at the site were simulated using the CHAIN_2D code without further calibration. The modelled PCE compared reasonably well with observed PCE concentrations in the pumped water. We also performed a scenario analysis by applying several increased reductive dechlorination rates, reflecting different degradation conditions (e.g. addition of yeast extract and citrate). The scenario analysis predicted considerably higher concentrations of the degradation products as a result of enhanced reductive dechlorination of PCE. The predicted levels of the very toxic compound VC were now an order of magnitude above the maximum permissible concentration levels.

Schaerlaekens, J.; Mallants, D.; Imûnek, J.; van Genuchten, M. Th.; Feyen, J.

1999-12-01

192

TCE Transport to Woburn Wells G and H  

NSDL National Science Digital Library

To prepare to view the TCE animation, students could view the 'A Civil Action' movie and the instructor could read to them excerpts from the trial testimony and images from Woburn, wells G and H, geologic materials, geologic cross sections, the trial participants, and the federal courtroom in Boston (available as a attachment to this activity and at a website listed below). The discussion in Bair (2001) about scientists in the courtroom, the specific (excerpted) testimony presented by the three expert witnesses in the 'A Civil Action' trial, a chart summarizing the differences in their testimony, and the views of a federal judge on the goal of science versus the goal of a civil trial may also be worthwhile reading by the class prior to the assignment. The instructor could also show students the large plates included in the USGS report by Myette and others (1987) that display potentiometric data and contours before and after the famous aquifer test performed in December 1985 and January 1986, just before the trial, and discuss the ramifications of having only two sets of water-level measurements to characterize all the changes in the flow system between 1964 and 1979, when wells G and H periodically operated. This makes students consider the substantial differences in making predictions based on a steady-state conceptualization of the flow system or a transient conceptualization. The instructor could also show the animation of induced infiltration from the Aberjona River to wells G and H that also was created by Martin van Oort (M.S., 2005) and based on the research of Maura Metheny (M.S., 1998; Ph.D., 2004) at Ohio State University. Viewing both animations enables students to see that the water produced by wells G and H is a highly transient mixture derived from many different source areas within the valley. The article by Bair and Metheny (2002) concerning the remediation activities at the Wells G & H Superfund Site could be used to show how groundwater contamination is cleaned up, why different remediation schemes needed to be used in different hydrogeologic settings, and why cleanup to U.S. EPA standards can take decades.

Bair, Scott

193

Characterization of an Enriched Anaerobic Culture Having Ability to Dechlorinate TCE  

NASA Astrophysics Data System (ADS)

An anaerobic mixed microbial culture was enriched from soil and groundwater taken from a site contaminated with trichloroethene (TCE). This enrichment culture could dechlorinate TCE sequentially to cis-dichloroethene (cis-DCE), vinyl chloride (VC), and ethene rapidly within 2 weeks. This enrichment culture could utilize various organic compounds, such as methanol, ethanol, and sodium acetate and so on, as electron donor. This culture had maintained high ability of TCE dechlorination for about 3 years since the start of enrichment cultivation. The optimum pH value for the dechlorination activity of this culture, which reacts from TCE to ethene, was 6.7. However above the pH value 7.1, it lost the dechlorination ability of cis-DCE and VC. So cis-DCE was remained at that pH conditions. From the DNA sequencing analysis of 16SrRNA gene, this enrichment culture includes Dehalococcoides sp. which has the ability to dechlorinate TCE to VC completely with hydrogen. It suggested that this Dehalococcoides sp. takes part in the dechlorination of chloroethenes.

Ise, K.; Suto, K.; Inoue, C.

2007-03-01

194

FY01 Phytoremediation of Chlorinated Ethenes in Southern Sector Seepline Sediments of SRS  

SciTech Connect

This treatability study is now in the second year of deployment for the Southern Sector Phytoremediation Project. Phytoremediation is the use of vegetation and associated media to treat contaminated soils, sediments, and groundwater. Phytoremediation is a rapidly developing technology that promises effective and safe cleanup of certain hazardous wastes. This ongoing work addresses the fate of volatile organic contaminants (VOCs) in an experiment that simulates a vegetated seepline supplied with trichloroethylene- (TCE-) and perchloroethylene- (PCE-) contaminated groundwater. The primary objective is to determine how the trees and sediments uptake groundwater TCE and PCE, biodegrade it, and/or transform it. The experimental focus of this project is the biological removal of VOCs from seepline groundwater and sediments.

Brigmon, R.L.

2004-01-30

195

The Observation of the Change of TCE Caused by Different Acupuncture Stimulation  

PubMed Central

Purpose. To observe the change of transcutaneous CO2 emission on meridian points or nonacupoints when the different needle sensations were gotten and study the associativity between Deqi acupuncture and periphery constitution energy metabolism effect. Method. 20 healthy volunteers were punctured on Neiguan (P6) in different ways including sham, shallow, Deqi acupuncture, and Deqi plus pressed P5, and measured TCE of different points before, during, and after acupuncture. Result. Needle sensations of sham acupuncture and shallow acupuncture were less than those of Deqi acupuncture. TCE of meridian points increased significantly and showed the specificity of meridian/channels. Conclusion. Verum acupuncture could cause the stronger needling sensations including distention, aching, numbness, and tingling than sham and shallow acupuncture. The strength of needling sensation caused by Deqi acupuncture is moderate and brought the best curative effects in TCE measurement. Deqi acupuncture could improve the energy metabolism of the points on the corresponding meridian/channel.

Huang, Tao; Cheng, Xinnong

2013-01-01

196

Characterization of uranium surfaces machined with aqueous propylene glycol-borax or perchloroethylene-mineral oil coolants  

SciTech Connect

The use of perchloroethylene (perc) as an ingredient in coolants for machining enriched uranium at the Oak Ridge Y-12 Plant has been discontinued because of environmental concerns. A new coolant was substituted in December 1985, which consists of an aqueous solution of propylene glycol with borax (sodium tetraborate) added as a nuclear poison and with a nitrite added as a corrosion inhibitor. Uranium surfaces machined using the two coolants were compared with respects to residual contamination, corrosion or corrosion potential, and with the aqueous propylene glycol-borax coolant was found to be better than that of enriched uranium machined with the perc-mineral oil coolant. The boron residues on the final-finished parts machined with the borax-containing coolant were not sufficient to cause problems in further processing. All evidence indicated that the enriched uranium surfaces machined with the borax-containing coolant will be as satisfactory as those machined with the perc coolant.

Cristy, S.S.; Bennett, R.K. Jr.; Dillon, J.J.; Richards, H.L.; Seals, R.D.; Byrd, V.R.

1986-12-31

197

A study of the effect of perchloroethylene exposure on the reproductive outcomes of wives of dry-cleaning workers  

SciTech Connect

The purpose of this investigation was to compare the reproductive outcomes of wives of men exposed to perchloroethylene in the dry-cleaning industry compared to those of wives of laundry workers. Seventeen female partners of dry cleaners and 32 partners of laundry workers were interviewed. The number of pregnancies and the standardized fertility ratios were similar between the two groups. Wives of dry cleaners did not have higher rates of spontaneous abortions. However, wives of dry cleaners were more than twice as likely to have a history of attempting to become pregnant for more than 12 months or to have sought care for an infertility problem. Cox proportional hazards models indicated that dry-cleaners' wives had half of the per-cycle pregnancy rate of wives of laundry workers, when controlling for other potential confounders (estimated rate ratio of 0.54, 95% C.I. = 0.23, 1.27).

Eskenazi, B.; Fenster, L.; Hudes, M.; Wyrobek, A.J.; Katz, D.F.; Gerson, J.; Rempel, D.M. (Program of Maternal and Child Health, School of Public Health, University of California, Berkeley (United States))

1991-01-01

198

INFLUENCE OF HYDRAULIC RETENTION TIME ON EXTENT OF PCE DECHLORINATION AND PRELIMINARY CHARACTERIZATION OF THE ENRICHMENT CULTURE. (R826694C703)  

EPA Science Inventory

The extent of tetrachloroethene (PCE) dechlorination in two chemostats was evaluated as a function of hydraulic retention time (HRT). The inoculum of these chemostats was from an upflow anaerobic sludge blanket (UASB) reactor that rapidly converts PCE to vinyl chloride (VC) an...

199

PCE-based scalable dynamic path control for large-scale photonic networks  

NASA Astrophysics Data System (ADS)

This paper proposes an inter-domain path control system based on PCE (Path Computation Element) for large-scale photonic networks, especially for a photonic network across over multiple carrier domains. We discuss the overall architecture of multi-domain optical network control system. The system utilizes maximum flow information in path computation and Path Key scheme in signaling, which improve the load-balancing and the confidentiality of the inside information for the route computation and the path provisioning among different carriers. We also provide measured performance results for inter-domain path computation and path setups using global optimization scheme, estimating the path provisioning time at the network scale dependency with the route computation time and the signaling time. As a result, we show its applicability to a 1000-node scale photonic network.

Araki, Soichiro; Shimada, Kohei; Hasegawa, Hiroshi; Sato, Ken-Ichi; Iizawa, Yohei; Ishida, Shinya; Nishioka, Itaru

2011-01-01

200

The PACSAT Communications Experiment (PCE). Final report, August 13, 1990--February 12, 1992  

SciTech Connect

While VITA (Volunteers in Technical Assistance) is the recognized world leader in low earth orbiting (LEO) satellite technology (below 1 GHz), its involvement in communications technologies is to facilitate renewable energy technology transfer to developing countries. A communications payload was incorporated into the UoSat 2 satellite (Surrey Univ., UK), launched in 1984; a prototype satellite (PCE) was also launched Jan 1990. US DOE awarded a second grant to VITA to design and test the prototype ground stations (command and field), install field ground stations in several developing country sites, pursue the operational licensing process, and transfer the evaluation results to the design of an operating system. This report covers the principal tasks of this grant.

Not Available

1993-02-12

201

Use Of Statistical Tools To Evaluate The Reductive Dechlorination Of High Levels Of TCE In Microcosm Studies  

EPA Science Inventory

A large, multi-laboratory microcosm study was performed to select amendments for supporting reductive dechlorination of high levels of trichloroethylene (TCE) found at an industrial site in the United Kingdom (UK) containing dense non-aqueous phase liquid (DNAPL) TCE. The study ...

202

Carbon isotope fractionation during reductive dechlorination of TCE in batch experiments with iron samples from reactive barriers  

Microsoft Academic Search

Reductive dechlorination of trichloroethene (TCE) by zero-valent iron produces a systematic enrichment of 13C in the remaining substrate that can be described using a Rayleigh model. In this study, fractionation factors for TCE dechlorination with iron samples from two permeable reactive barriers (PRBs) were established in batch experiments. Samples included original unused iron as well as material from a barrier

Christoph Schüth; Markus Bill; Johannes A. C. Barth; Gregory F. Slater; Robert M. Kalin

2003-01-01

203

Validation and application of pharmacokinetic models for interspecies extrapolations in toxicity risk assessments of volatile organics. Annual report No. 2, 1 July 1988-30 June 1989  

SciTech Connect

In pursuit of the goal of establishing a scientific basis for the interspecies extrapolation of pharmacokinetic data in health-risk assessments, a series of studies were conducted involving pharmacokinetic determinations in rats to several aliphatic halocarbons (with parallel studies initiated in the dog). Direct measurements of the uptake and elimination of halocarbon in rats were completed during the following inhalation exposures and following oral administration of dichloroethylene (DCE) and perchloroethylene (PCE). An assay for the measurement of halocarbons in the tissues of exposed animals has been successfully developed, and tissue-concentration profiles in the liver, kidney, lung, fat, brain, muscle, and heart were completed for oral and intraarterial administrations of PCE. The utility of the physiologically-based pharmacokinetic model for the accurate computer simulations of the pharmacokinetics of three halocarbons with wide variation in physicochemical properties (TRI, TCE, and PCE) has been demonstrated.

Dallas, C.E.; Bruckner, J.V.; Gallo, J.; Ramanathan, R.; Muralidhara, S.

1989-07-21

204

Preliminary technology report for Southern Sector bioremediation  

SciTech Connect

This project was designed to demonstrate the potential of intrinsic bioremediation and phytoremediation in the Southern Sector of the A/M-Area at the Savannah River Site. A subsurface plume of trichloroethylene (TCE) and perchloroethylene (PCE) is present in the Lost Lake aquifer upgradient of the study site and is predicted to impact the area at some point in the future. The surface area along the Lost lake aquifer seep line where the plume is estimated to emerge was identified. Ten sites along the seep line were selected for biological, chemical, and contaminant treatability analyses. A survey was undertaken in this area to to quantify the microbial and plant population known to be capable of remediating TCE and PCE. The current groundwater quality upgradient and downgradient of the zone of influence was determined. No TCE or PCE was found in the soils or surface water from the area tested at this time. A TCE biodegradation treatability test was done on soil from the 10 selected locations. From an initial exposure of 25 ppm of TCE, eight of the samples biodegraded up to 99.9 percent of all the compound within 6 weeks. This biodegradation of TCE appears to be combination of aerobic and anaerobic microbial activity as intermediates that were detected in the treatability test include vinyl chloride (VC) and the dichloroethenes (DCE) 1,2-cis-dichloroethylene and 1,1-dichloroethylene. The TCE biological treatability studies were combines with microbiological and chemical analyses. The soils were found through immunological analysis with direct fluorescent antibodies (DFA) and microbiological analysis with direct fluorescent antibodies (DFA) and microbiological analysis to have a microbial population of methanotrophic bacteria that utilize the enzyme methane monooxygenase (MMO) and cometabolize TCE.

Brigmon, R.L.; White, R.; Hazen, T.C.; Jones, D.; Berry, C.

1997-06-01

205

Prediction of temperature cycling life for SMT solder joints on TCE-mismatched substrates  

Microsoft Academic Search

A method for the prediction of solder-joint cycle life in surface-mount assemblies is presented. It is based on the conversion of plastic solder shear strain into cycle life with an equation derived by W. Engelmaier (1983). The shear strain is normally calculated from temperature and TCE (thermal coefficient of expansion) differentials between the package and interconnect board without consideration of

Dietrich E. Riemer

1990-01-01

206

Byproduct formation during the reduction of TCE by zero-valence iron and palladized iron  

Microsoft Academic Search

The use of zero-valence metals for reduction of chlorinated solvents such as trichloroethene (TCE) has been an area of significant recent research. The proposed method has great attraction because the reactive media, iron filings, are relatively inexpensive. Moreover, remedial systems can be designed that rely on a passive funnel and gate approach that would minimize the cost of operation and

Liyuan Liang; Nic Korte; J. D. Goodlaxson; Jay Clausen; Quintus Fernando; Rosy Muftikian

1997-01-01

207

Diversity of Pristine Methanotrophic Communities in a Basalt Aquifer: Implications for Natural Attenuation of TCE  

NASA Astrophysics Data System (ADS)

Natural attenuation of a large trichloroethylene (TCE) plume within the oxic Snake River Plain Aquifer (SRPA) appears to be occurring by aerobic co-metabolism. Methanotrophs are some of the key TCE degraders known to inhabit the aquifer. To better understand the role methanotrophs may have in TCE degradation and the relationship of methanotrophs to dissolved methane concentrations, groundwater collected from wells in the SRPA was analyzed for geochemical properties and methanotroph diversity. Microorganisms removed from groundwater by filtration were used as inocula for enrichments or were frozen and subsequently extracted for DNA. Primers that target Type I and Type II methanotroph 16S rDNA or genes that code for soluble (mmoX) and particulate (pmoA) methane monooxygenase subunits were used to characterize the indigenous methanotrophs via PCR, cloning, and sequencing. Groundwater had dissolved methane concentrations that ranged from 1 to >1000 nM. Analysis of sequencing results suggest that the group Methylocystaceae is a predominant Type II methanotroph in each sample. Methanotrophs can be detected and enriched from groundwater containing even low methane concentrations. Analysis of gene sequences provides assessments of methanotroph abundance and diversity with respect to the aquifer methane concentrations, imparting greater insight into the genetic potential of the microbial community capable of degrading TCE. This research will continue to focus on the evaluation of natural attenuation by methanotrophs.

Reed, D. W.; Newby, D. T.; Delwiche, M. E.; Igoe, A.; McKinley, J. P.; Roberto, F. F.; Colwell, F. S.

2001-12-01

208

Steam Stripping\\/Hydrous Pyrolysis Oxidation for In-Situ Remediation of a TCE DNAPL Spill  

Microsoft Academic Search

A field demonstration of Steam Stripping and Hydrous Pyrolysis Oxidation (SS\\/HPO) was conducted at the Portsmouth DOE facility in Ohio. A trichloroethene (TCE) release at the site had led to DNAPL concentration in a semi-confined water bearing zone in the overburden, and in the upper part of a bedrock shale layer. It was demonstrated that steam injection can heat the

Gorm Heron; Steven Carroll; Hank Sowers

209

RATE OF TCE DEGRADATION IN A PLANT MULCH PASSIVE REACTIVE BARRIER (BIOWALL)  

EPA Science Inventory

A passive reactive barrier was installed at the OU-1 site at Altus Air Force Base, Oklahoma to treat TCE contamination in ground water from a landfill. Depth to ground water varies from 1.8 to 2.4 meters below land surface. To intercept and treat the plume of contaminated groun...

210

EFFECTIVE REMOVAL OF TCE IN A LABORATORY MODEL OF A PRB CONSTRUCTED WITH PLANT MULCH  

EPA Science Inventory

Ground water contaminated with TCE is commonly treated with a permeable reactive barrier (PRB) constructed with zero-valence iron. The cost of iron as the reactive matrix has driven a search for less costly alternatives, and composted plant mulch has been used as an alternative ...

211

FIELD SCALE EVALUATION OF TREATMENT OF TCE IN A BIOWALL AT THE OU-1 SITE  

EPA Science Inventory

A passive reactive barrier (Biowall) was installed at the OU-1 site at Altus Air Force Base, Oklahoma to treat TCE contamination in ground water from a landfill. Depth to ground water varies from 1.8 to 2.4 meters below land surface. To intercept and treat the plume of contamin...

212

Remediation of TCE-contaminated groundwater by a permeable reactive barrier filled with plant mulch (Biowall).  

PubMed

A pilot-scale permeable reactive barrier filled with plant mulch was installed at Altus Air Force Base in Oklahoma, USA to treat trichloroethylene (TCE) contamination in groundwater emanating from a landfill. The barrier was constructed in June 2002. It was 139 meters long, 7 meters deep, and 0.5 meters wide. The barrier is also called a Biowall because one of the mechanisms for removal of TCE is anaerobic biodegradation. This study aimed at evaluating the performance of the pilot-scale Biowall after its installation. Data from over four years' monitoring indicated that the Biowall greatly changed geochemistry in the study area and stimulated TCE removal. The concentration of TCE in the Biowall and downgradient of the Biowall was greatly reduced as compared to that in ground water upgradient of the Biowall, while the concentration of cis-DCE in the Biowall and downgradient of the Biowall was much higher than that observed upgradient of the Biowall. Over time, the concentration of vinyl chloride in the Biowall and downgradient of the Biowall increased. Dehalococcoides DNA was detected within and downgradient of the Biowall, corresponding to the observation that vinyl chloride was produced at these locations. Results from a tracer study indicated that the regional groundwater flow pattern ultimately determined the flow direction in the area around the Biowall. The natural groundwater velocity was estimated at an average of 0.060 +/- 0.015 m/d. PMID:18161555

Lu, Xiaoxia; Wilson, John T; Shen, Hai; Henry, Bruce M; Kampbell, Donald H

2008-01-01

213

Outcomes from the targeted capacity expansion (TCE) substance abuse treatment program  

Microsoft Academic Search

The Substance Abuse and Mental Health Services Administration (SAMHSA) Center for Substance Abuse Treatment (CSAT), in carrying out its mission to improve access to and the quality of substance abuse treatment services, initiated the Targeted Capacity Expansion (TCE) program—a national initiative, to encourage community-based organizations to expand their existing treatment capacity and implement strategies to evaluate treatment outcomes. Additionally, CSAT

Maurice T. Wilson; Robert Atanda; Donna Durant Atkinson; Kevin Mulvey

2005-01-01

214

A SEARCH FOR RESIDUAL BEHAVIORAL EFFECTS OF TRICHLOROETHYLENE (TCE) IN RATS EXPOSED AS YOUNG ADULTS  

EPA Science Inventory

Trichloroethylene (TCE) is a solvent of concern to the EPA due to its extensive use in industry, its prevalence in urban air, and its appearance in water supplies. Human clinical studies have associated short and long-termsolvent exposures with cognitive dysfunction including att...

215

Remediation of TCE-contaminated groundwater by a permeable reactive barrier filled with plant mulch (Biowall)  

Microsoft Academic Search

A pilot-scale permeable reactive barrier filled with plant mulch was installed at Altus Air Force Base in Oklahoma, USA to treat trichloroethylene (TCE) contamination in groundwater emanating from a landfill. The barrier was constructed in June 2002. It was 139 meters long, 7 meters deep, and 0.5 meters wide. The barrier is also called a Biowall because one of the

Xiaoxia Lu; John T. Wilson; Hai Shen; Bruce M. Henry; Donald H. Kampbell

2007-01-01

216

Development of an updated PBPK model for trichloroethylene and metabolites in mice, and its application to discern the role of oxidative metabolism in TCE-induced hepatomegaly  

Microsoft Academic Search

Trichloroethylene (TCE) is a lipophilic solvent rapidly absorbed and metabolized via oxidation and conjugation to a variety of metabolites that cause toxicity to several internal targets. Increases in liver weight (hepatomegaly) have been reported to occur quickly in rodents after TCE exposure, with liver tumor induction reported in mice after long-term exposure. An integrated dataset for gavage and inhalation TCE

M. V. Evans; W. A. Chiu; M. S. Okino; J. C. Caldwell

2009-01-01

217

Reduction of occupational exposure to perchloroethylene and trichloroethylene in metal degreasing over the last 30 years: influences of technology innovation and legislation  

Microsoft Academic Search

Occupational exposure to trichloroethylene (TRIC) and perchloroethylene (PERC) in metal degreasing is analyzed by calculating airborne concentrations for a large set of possible exposure scenarios (Scenario-Based Risk Assessment, SceBRA). Different types of degreasing machines ranging from open-top machines used until the 1980s to closed-loop nonvented machines used since the 1990s are investigated; the scope of the study is Germany. Concentrations

Julia von Grote; Christian Hürlimann; Martin Scheringer; Konrad Hungerbühler

2003-01-01

218

Application of electrolysis to stimulate microbial reductive PCE dechlorination and oxidative VC biodegradation.  

PubMed

A novel approach was applied to stimulate biodegradation of chloroethenes bya coupled bioelectro-process. In a flow-through column system, microbial dechlorination of tetrachloroethene to cis-dichloroethene, vinyl chloride, and ethene was stimulated by hydrogen produced by water electrolysis. Dechlorinating bacteria (Dehalococcoides spp. and Desulfitobacterium spp.) and also methanogens and homoacetogens were detected in the anaerobic column. Simultaneously, oxidative biodegradation of lower chlorinated metabolites (vinyl chloride) was stimulated by electrolytic oxygen formation in the corresponding aerobic column. The process was stable for more than 100 days and an average removal of approximately 23 micromol/d PCE and 72 micromo/d vinyl chloride was obtained with a current density of 0.05 mA/cm2. Abiotic electrochemical degradation of the contaminants was not observed. Microbial dechlorination correlated with the current densities in the applied range of 0.01-0.05 mA/cm2. The results are promising for environmental applications, since with electrolysis hydrogen and oxygen can be supplied continuously to chloroethene degrading microorganisms, and the supply rates can be easily controlled by adjusting the electric current. PMID:19806748

Lohner, Svenja T; Tiehm, Andreas

2009-09-15

219

Modeling of TCE and Toluene Toxicity to Pseudomonas putida F1  

NASA Astrophysics Data System (ADS)

Prediction of viable bacterial distribution with respect to contaminants is important for efficient bioremediation of contaminated ground-water aquifers, particularly those contaminated with residual NAPLs. While bacterial motility and chemotaxis may help situate bacteria close to high concentrations of contaminant thereby enhancing bioremediation, prolonged exposure to high concentrations of contaminates is toxic to contaminant-degrading bacteria. The purpose of this work is to model the toxicity of trichloroethylene and toluene to Pseudomonas putida F1. The Live/Dead® bacterial viability assay was used to determine the toxic effect of chemical contaminants on the viability of P. putida F1 in a sealed zero head-space experimental environment. Samples of bacterial suspensions were exposed to common ground-water pollutants, TCE and toluene, for different durations. Changes in live and dead cell populations were monitored over the course of experiments using fluorescence microscopy. Data obtained from these toxicity experiments were fit to simple linear and exponential bacterial decay models using non-linear regression to describe loss of bacterial viability. TCE toxicity to P. putida F1 was best described with an exponential decay model (Figure 1a), with a decay constant kTCE = 0.025 h-4.95 (r2 = 0.956). Toluene toxicity showed a marginally better fit to the linear decay model (Figure 1b) (r2 = 0.971), with a decay constant ktoluene = 0.204 h-1. Best-fit model parameters obtained for both TCE and toluene were used to predict bacterial viability in toxicity experiments with higher contaminant concentrations and matched well with experimental data. Results from this study can be used to predict bacterial accumulation and viability near NAPL sources, and thus may be helpful in improving bioremediation performance assessment of contaminated sites. Figure 1: Survival ratios (S = N/No) of P. putida F1 in TCE- (a) and toluene- (b) stressed samples (observed (‘x’), linear model (‘—’) and exponential model (‘---’)) and non-TCE stressed samples (‘o’) at different time intervals throughout toxicity experiments. Error bars represent standard errors for five replicate experiments.

Singh, R.; Olson, M. S.

2009-12-01

220

A novel PCE-based algorithm for P2MP inter-domain traffic engineering in optical networks  

NASA Astrophysics Data System (ADS)

Point-to-Multipoint (P2MP) services in optical networks are more and more important for high-capacity applications. Steiner tree algorithms have been investigated to compute minimum-cost multicast tree. However, it is difficult to compute an optimal P2MP tree in multi-domain networks because of isolation of each domain. There are several algorithms based on Path Computation Element (PCE) for computing multi-domain Point-to-point path, but computing P2MP Traffic Engineering Label Switched Path (TE-LSP) in a multi-domain networks is still a challenge. In this paper, three PCE-based schemes for P2MP inter-domain LSP computation are compared in full splitting capability networks, and a novel Multi-Domain Minimum-cost Path Heuristic (MDMPH) algorithm is proposed. Simulation results proved that the MDMPH algorithm computes P2MP tree with less cost than the other three schemes.

Wu, Koubo; Zhang, Jie; Zhao, Yongli; Yu, Ziyan; Gu, Wanyi; Wang, Dajiang; Cao, Xuping

2011-11-01

221

Phenyl methyl ethers: novel electron donors for respiratory growth of Desulfitobacterium hafniense and Desulfitobacterium sp. strain PCE-S  

Microsoft Academic Search

Desulfitobacterium hafniense and Desulfitobacterium sp. strain PCE-S grew under anoxic conditions with a variety of phenyl methyl ethers as electron donors in combination with fumarate as electron acceptor. The phenyl methyl ethers were O-demethylated to the corresponding phenol compounds. O-demethylation was strictly dependent on the presence of fumarate; no O-demethylation occurred with CO 2 as electron acceptor. One mol phenyl

Anke Neumann; Tina Engelmann; Roland Schmitz; Yvonne Greiser; Adelheid Orthaus; Gabriele Diekert

2004-01-01

222

CIS-DCE AND VC MICROBIAL COMMUNITY CHANGES ASSOCIATED WITH A SHIFT FROM REDUCTIVE DECHLORINATION OF PCE TO REDUCTIVE DECHLORINATION OF  

EPA Science Inventory

Subcultures that reductively dechlorinate cis-dichloroethene (cis-DCE) or vinyl chloride (VC) were derived from three independent enrichments that completely dechlorinated tetrachloroethene (PCE) to ethene in order to study the reductive dechlorination of the lesser chlorinated e...

223

TCE field-scale simulation using immobile-mobile waste phase model  

SciTech Connect

Groundwater contamination resulting from releases of chlorinated volatile organic compounds into the environment is commonplace. Industrial solvents, such as trichloroethylene (TCE), were historically released into top soils as a means of disposal. At numerous sites nationwide, cleanup efforts are underway. To evaluate the benefits associated with proposed remediation alternatives, flow and transport modeling is playing an ever increasing role. In many situations site characterization of contaminant source terms is very sketchy, resulting in a lack of necessary data to develop a reliable source term model directly from a database. As such, investigators are forced into an approach of estimating the source term in an inverse modeling fashion. Field-scale attempts are made here to predict the fate and transport of TCE under various remediation alternatives. Under a no action scenario, inverse modeling to establish the source term is performed where comparison to field measurements are made.

Hamm, L.L.; Aleman, S.E.; Shadday, M.A.

1997-05-01

224

In Situ Redox Manipulation of Subsurface Sediments from Fort Lewis, Washington: Iron Reduction and TCE Dechlorination Mechanisms  

SciTech Connect

The feasibility of chemically treating sediments from the Ft. Lewis, Washington, Logistics Center to develop a permeable barrier for dechlorination of TCE was investigated in a series of laboratory experiments.

Szecsody, James E.; Fruchter, Jonathan S.; Sklarew, Deborah S.; Evans, John C.

2000-03-17

225

Use of Fenton's Reagent for the Degradation of TCE in Aqueous Systems and Soil Slurries  

Microsoft Academic Search

Fenton's reaction is comprised of hydrogen peroxide (H2O2) catalyzed by iron, producing the hydroxyl radical (·OH), a strong oxidant. ·OH in turn may react with H2O2 and iron and is capable of destroying a wide range of organic contaminants. In this laboratory study, Fenton's reaction was observed in aqueous and soil slurry systems using trichloroethylene (TCE) as the target contaminant,

Clifford J. Bruell; Nihar R. Mohanty

2000-01-01

226

Microcosm evaluation of bioaugmentation after field-scale thermal treatment of a TCE-contaminated aquifer.  

PubMed

This paper investigates effects of combining thermal and biological remediation, based on laboratory studies of trichloroethene (TCE) degradation. Aquifer material was collected 6 months after terminating a full-scale Electrical Resistance Heating (ERH), when the site had cooled from approximately 100 degrees C to 40 degrees C. The aquifer material was used to construct bioaugmented microcosms amended with the mixed anaerobic dechlorinating culture, KB-1(TM), and an electron donor (5 mM lactate). Microcosms were bioaugmented during cooling at 40, 30, 20, and 10 degrees C, as temperatures continually decreased during laboratory incubation. Redox conditions were generally methanogenic, and electron donors were present to support dechlorination. For microcosms bioaugmented at 10 degrees C and 20 degrees C, dechlorination stalled at cis-dichloroethene (cDCE) and vinyl chloride (VC) 150 days after bioaugmentation. However, within 300 days of incubation ethene was produced in the majority of these microcosms. In contrast, dechlorination was rapid and complete in microcosms bioaugmented at 30 degrees C. Microcosms bioaugmented at 40 degrees C also showed rapid dechlorination, but stalled at cDCE with partial VC and ethene production, even after 150 days of incubation when the temperature had decreased to 10 degrees C. These results suggest that sequential bioremediation of TCE is possible in field-scale thermal treatments after donor addition and bioaugmentation and that the optimal bioaugmentation temperature is approximately 30 degrees C. When biological and thermal remediations are to be applied at the same location, three bioremediation approaches could be considered: (a) treating TCE in perimeter areas outside the source zone at temperatures of approximately 30 degrees C; (b) polishing TCE concentrations in the original source zone during cooling from approximately 30 degrees C to ambient groundwater temperatures; and (c) using bioremediation in downgradient areas taking advantages of the higher temperature and potential release of organic matter. PMID:17225076

Friis, Anne Kirketerp; Kofoed, Julie L L; Heron, Gorm; Albrechtsen, Hans-Jørgen; Bjerg, Poul L

2007-01-16

227

Electrochemically induced dual reactive barriers for transformation of TCE and mixture of contaminants in groundwater.  

PubMed

A novel reactive electrochemical flow system consisting of an iron anode and a porous cathode is proposed for the remediation of mixture of contaminants in groundwater. The system consists of a series of sequentially arranged electrodes, a perforated iron anode, a porous copper cathode followed by a mesh-type mixed metal oxide anode. The iron anode generates ferrous species and a chemically reducing environment, the porous cathode provides a reactive electrochemically reducing barrier, and the inert anode provides protons and oxygen to neutralize the system. The redox conditions of the electrolyte flowing through this system can be regulated by controlling the distribution of the electric current. Column experiments are conducted to evaluate the process and study the variables. The electrochemical reduction on a copper foam cathode produced an electrode-based reductive potential capable of reducing TCE and nitrate. Rational electrodes arrangement, longer residence time of electrolytes and higher surface area of the foam electrode improve the reductive transformation of TCE. More than 82.2% TCE removal efficiency is achieved for the case of low influent concentration (<7.5 mg/L) and high current (>45 mA). The ferrous species produced from the iron anode not only enhance the transformation of TCE on the cathode, but also facilitates transformation of other contaminants including dichromate, selenate and arsenite. Removal efficiencies greater than 80% are achieved for these contaminants in flowing contaminated water. The overall system, comprising the electrode-based and electrolyte-based barriers, can be engineered as a versatile and integrated remedial method for a relatively wide spectrum of contaminants and their mixtures. PMID:23067023

Mao, Xuhui; Yuan, Songhu; Fallahpour, Noushin; Ciblak, Ali; Howard, Joniqua; Padilla, Ingrid; Loch-Caruso, Rita; Alshawabkeh, Akram N

2012-10-15

228

Surfactant foam\\/bioaugmentation technology for in situ treatment of TCE-DNAPLs  

Microsoft Academic Search

Chlorinated solvents such as trichloroethylene (TCE) are prevalent aquifer contaminants. Depending on the degree of contamination, their physical properties may cause them to occur as dense nonaqueous-phase liquids (DNAPLs) making them difficult to remediate by pump-and-treat methods. Successful in situ bioremediation requires mobilization and dispersion of DNAPLs in order to reduce sediment concentrations to levels nontoxic to degradative bacteria. A

Randi K. Rothmel; Robert W. Peters; Edward St. Martin; Mary F. DeFlaun

1998-01-01

229

Isolation of transfer-negative nif -plasmids (pCE1) and their integration into the chromosome of Escherichia coli with the help of phage Mu  

Microsoft Academic Search

Strain JC5466 of Escherichia coli K12 harbouring the nitrogen fixation plasmid pCE1 was lysogenized with bacteriophage Mu cts, followed by partial induction and infection with bacteriophage PRD1. This made it possible to obtain transfer-defective derivatives of pCE1, carrying Mu prophage. These derivatives could be mobilized by using the helper plasmid pME400 and it was possible to segregate the helper plasmid

M. Giitffert; W. Klingmiiller

1985-01-01

230

Characterization of four TCE-dechlorinating microbial enrichments grown with different cobalamin stress and methanogenic conditions.  

PubMed

To investigate the important supportive microorganisms responsible for trichloroethene (TCE) bioremediation under specific environmental conditions and their relationship with Dehalococcoides (Dhc), four stable and robust enrichment cultures were generated using contaminated groundwater. Enrichments were maintained under four different conditions exploring two parameters: high and low TCE amendments (resulting in inhibited and uninhibited methanogenic activity, respectively) and with and without vitamin B?? amendment. Lactate was supplied as the electron donor. All enrichments were capable of reductively dechlorinating TCE to vinyl chloride and ethene. The dechlorination rate and ethene generation were higher, and the proportion of electrons used for dechlorination increased when methanogenesis was inhibited. Biologically significant cobalamin biosynthesis was detected in the enrichments without B?? amendment. Comparative genomics using a genus-wide microarray revealed a Dhc genome similar to that of strain 195 in all enrichments, a strain that lacks the major upstream corrin ring biosynthesis pathway. Seven other bacterial operational taxonomic units (OTUs) were detected using clone libraries. OTUs closest to Pelosinus, Dendrosporobacter, and Sporotalea (PDS) were most dominant. The Clostridium-like OTU was most affected by B?? amendment and active methanogenesis. Principal component analysis revealed that active methanogenesis, rather than vitamin B?? limitation, exerted a greater effect on the community structures even though methanogens did not seem to play an essential role in providing corrinoids to Dhc. In contrast, acetogenic bacteria that were abundant in the enrichments, such as PDS and Clostridium sp., may be potential corrinoid providers for Dhc. PMID:23640361

Men, Yujie; Lee, Patrick K H; Harding, Katie C; Alvarez-Cohen, Lisa

2013-05-03

231

In situ detection of organic molecules: Optrodes for TCE (trichloroethylene) and CHCl sub 3  

SciTech Connect

We have developed new absorption-based chemical indicators for detecting chloroform (CHCl{sub 3}) and trichloroethylene (TCE). These indicators were used to make very sensitive optical chemical sensors (optrodes) for each of these two contaminants. Concentrations below 10 ppb can be accurately measured using these sensors. Furthermore, they are selective and do not response to similar contaminants commonly found with TCE and CHCl{sub 3} in contaminated groundwater. In addition, the sensor response is linearly proportional to the chemical concentration. In this report, we describe the details of this optrode and the putative reaction sequences of the indicator chemistries with CHCl{sub 3} and TCE and present an analysis of the spectral data obtained from the reaction products. A key part of the development of this optrode was designing a simple readout device. The readout is a dual-channel fiber-optic fluorimeter modified to measure transmission or absorption of light. The system is controlled by a lap-top microcomputer and is fully field portable. In addition to describing the final absorption optrode, details of the chemical indicator reactions are presented for both absorption- (colorimetric) and fluorescence-based optrodes. Finally, we report on the syntheses of several compounds used to evaluate the indicator chemical reactions that led to the development of the absorption optrode. 23 refs., 26 figs., 1 tab.

Angel, S. M.; Langry, K. C.; Ridley, M. N.

1990-05-01

232

The role of microbial reductive dechlorination of TCE at a phytoremediation site.  

PubMed

In April 1996, a phytoremediation field demonstration site at the Naval Air Station, Fort Worth, Texas, was developed to remediate shallow oxic ground water (< 3.7 m deep) contaminated with chlorinated ethenes. Microbial populations were sampled in February and June 1998. The populations under the newly planted cottonwood trees had not yet matured to an anaerobic community that could dechlorinate trichloroethene (TCE) to cis-1,2-dichloroethene (DCE); however, the microbial population under a mature (approximately 22-year-old) cottonwood tree about 30 m southwest of the plantings had a mature anaerobic population capable of dechlorinating TCE to DCE, and DCE to vinyl chloride (VC). Oxygen-free sediment incubations with contaminated groundwater also demonstrated that resident microorganisms were capable of the dechlorination of TCE to DCE. This suggests that a sufficient amount of organic material is present for microbial dechlorination in aquifer microniches where dissolved O2 concentrations are low. Phenol, benzoic acid, acetic acid, and a cyclic hydrocarbon, compounds consistent with the degradation of root exudates and complex aromatic compounds, were identified by gas chromatography/mass spectrometry (GC/MS) in sediment samples under the mature cottonwood tree. Elsewhere at the site, transpiration and degradation by the cottonwood trees appears to be responsible for loss of chlorinated ethenes. PMID:12710236

Godsy, E Michael; Warren, Ean; Paganelli, Victor V

2003-01-01

233

Development of a slow polycolloid-releasing substrate (SPRS) biobarrier to remediate TCE-contaminated aquifers.  

PubMed

In this study, an in situ slow polycolloid-releasing substrate (SPRS) biobarrier system was developed to continuously provide biodegradable substrates for the enhancement of trichloroethylene (TCE) reductive dechlorination. The produced SPRS contained vegetable oil (used as a slow-released substrate), cane molasses [used as an early-stage (fast-degradable) substrate], and surfactants [Simple Green (SG) and soya lecithin (SL)]. An emulsification study was performed to evaluate the globule droplet size and stability of SPRS. The distribution and migration of the SPRS were evaluated in a column experiment, and an anaerobic microcosm study was performed to assess the capability of SPRS to serve as a slow and long-term carbon-releasing substrate for TCE dechlorination. The results show that a stable oil-in-water (W/O, 50/50) emulsion (SPRS) with uniformly small droplets (D??, 0.93 ?m) has been produced, continuously supplying primary substrates. The emulsion containing the surfactant mixture (with 72 mg/L SL and 71 mg/L SG) had a small absolute value of the zeta potential, which reduced the inter-particle repulsion, leading the emulsion droplets to adhere to one another after collision. The addition of SPRS creates anaerobic conditions and leads to a more complete and thorough removal of TCE through biodegradation and sorption mechanisms. PMID:23611795

Liang, S H; Kuo, Y C; Chen, S H; Chen, C Y; Kao, C M

2013-03-26

234

Intercalation of TCE by Sediment-Associated Clay Minerals and Implications for Low-Concentration Elution Tailing and Back Diffusion  

NASA Astrophysics Data System (ADS)

Pump-and-treat systems are widely used to remediate hazardous waste sites wherein groundwater is contaminated by compounds such as TCE (trichloroethene). It is well known that removal of contaminant mass by pump and treat becomes less effective over time, with a persistent mass discharge causing greatly extended operational periods. One mechanism potentially responsible for this persistent mass discharge is "back diffusion", wherein dissolved contaminant stored in lower-permeability layers diffuses into the higher-permeability zones that are more readily swept via pump and treat. Because the lower-permeability layers typically contain high fractions of clay minerals, a question of great interest is whether contaminant-clay interactions may influence the back-diffusion process. For example, intercalation of TCE into the interlayer spaces of clay minerals could potentially exacerbate diffusive mass-transfer limitations. The primary objectives of this research were to evaluate the long-term elution of TCE from aquifer sediments, and to examine the potential for TCE intercalation. Sediment samples were collected from a TCE-contaminated field site in Tucson, AZ. A widely used Na- Montmorillonite specimen clay was used as a control. Miscible-displacement experiments were conducted to characterize TCE elution behavior. X-ray diffraction, conducted with a controlled environment chamber, was used to characterize smectite interlayer d-spacing for three treatments (bulk dry sample, sample mixed with synthetic groundwater, sample mixed with TCE-saturated synthetic groundwater). Extensive elution tailing was observed for the column experiments. Results of the XRD analysis indicate a greater d-spacing for the samples treated with TCE-saturated synthetic groundwater for all field samples as well as the specimen clay.

Matthieu, D. E.; Brusseau, M. L.; Bowden, M. E.; Johnson, G. R.; Artiola, J. F.; Curry, J. E.

2011-12-01

235

Remediation of TCE-contaminated groundwater using zero valent iron and direct current: experimental results and electron competition model  

Microsoft Academic Search

The objectives of this study are to design an optimal electro-enhanced permeable reactive barrier (E2PRB) system for the remediation\\u000a of trichloroethylene (TCE)-contaminated water using zero valent iron (ZVI) and direct current (DC) and to investigate the\\u000a mechanisms responsible for TCE degradation in different ZVI-DC configurations. A series of column experiments was conducted\\u000a to evaluate the effect of different arrangements of

Ji-Won Moon; Hi-Soo Moon; Heonki Kim; Yul Roh

2005-01-01

236

Electro-enhanced Permeable Reactive Barrier : Optimal Design of PRB System With External Current for Effective TCE Removal From Groundwater  

Microsoft Academic Search

The objective of this study was to design an optimal electro-enhanced permeable reactive barrier (E2PRB) system for remediation of trichloroethylene (TCE)-contaminated water using zero valent iron (ZVI) and direct current (DC). A series of column experiments were conducted to evaluate the location of Fe0 permeable reactive barrier (PRB) and the effects of electrode arrangement in the column on the TCE

J. Moon; H. Moon; Y. Roh; H. Kim; Y. Song

2002-01-01

237

Toward Distributed Translucent Wavelength Switched Optical Networks under GMPLS/PCE Architecture  

NASA Astrophysics Data System (ADS)

Recently, the GMPLS controlled WSON has emerged as a promising optical transport network. In order to guarantee the optical signal transmission feature without deformation, the optoelectronic 3R regenerators still need to be sparsely placed in the network, termed as translucent networks. The growing size and complexity of the translucent network requires a transition of control plane to move from the traditional centralized model to a fully distributed architecture in the future. However, centrally designed routing, wavelength assignment, and 3R regenerator allocation approaches become unfeasible under the distributed paradigm due to the outdated and inconsistent network state information. A common solution is to accelerate the update frequency of network state, but the fundamental problem remains that the inaccurate state information is still inevitable. Furthermore, it adds a significant increase to the control traffic volume which adversely degrades the performance and scalability of the network control system. In order to mitigate the impact of having inaccurate state information on network performance in the distributed systems, a novel RWA approach is proposed in this paper, termed as routing and distributed wavelength assignment with top ranked probing wavelength set computation. In our proposal, the wavelength assignment is performed by signalling process with a set of carefully preselected probing wavelengths. This set is dynamically computed based on the resource utilization each time the network state is refreshed. The PCE module is adopted in WSON control plane to be responsible for the computation of RWA and 3R allocation. The performance of the proposed approach is studied by extensive simulations. The experiment results reveal that by employing the proposed scheme, without loss on the blocking performance the inaccuracy of the wavelength availability information can be well tolerated, and the set-up delay in lightpath provisioning can be kept at a low level.

Wang, Xin; Chap, Tithra; Xu, Sugang; Tanaka, Yoshiaki

238

Electrocatalytic activity of Pd-loaded Ti/TiO2 nanotubes cathode for TCE reduction in groundwater.  

PubMed

A novel cathode, Pd loaded Ti/TiO2 nanotubes (Pd-Ti/TiO2NTs), is synthesized for the electrocatalytic reduction of trichloroethylene (TCE) in groundwater. Pd nanoparticles are successfully loaded on TiO2 nanotubes which grow on Ti plate via anodization. Using Pd-Ti/TiO2NTs as the cathode in an undivided electrolytic cell, TCE is efficiently and quantitatively transformed to ethane. Under conditions of 100 mA and pH 7, the removal efficiency of TCE (21 mg/L) is up to 91% within 120 min, following pseudo-first-order kinetics with the rate constant of 0.019 min(-1). Reduction rates increase from 0.007 to 0.019 min(-1) with increasing the current from 20 to 100 mA, slightly decrease in the presence of 10 mM chloride or bicarbonate, and decline with increasing the concentrations of sulfite or sulfide. O2 generated at the anode slightly influences TCE reduction. At low currents, TCE is mainly reduced by direct electron transfer on the Pd-Ti/TiO2NT cathode. However, the contribution of Pd-catalytic hydrodechlorination, an indirect reduction mechanism, becomes significant with increasing the current. Compared with other common cathodes, i.e., Ti-based mixed metal oxides, graphite and Pd/Ti, Pd-Ti/TiO2NTs cathode shows superior performance for TCE reduction. PMID:23726693

Xie, Wenjing; Yuan, Songhu; Mao, Xuhui; Hu, Wei; Liao, Peng; Tong, Man; Alshawabkeh, Akram N

2013-04-19

239

Neurotoxicologic examination of rats exposed to 1,1,2,2-tetrachloroethylene (perchloroethylene) vapor for 13 weeks.  

PubMed

Large evoked potential and EEG changes occurred in a pilot study in Fischer 344 rats during exposure to 800 ppm of 1,1,2,2-tetrachloroethylene [perchloroethylene (Perc)], a cleaning solvent with anesthetic properties. In the main study, rats were evaluated for persistent nervous system effects the week following exposure to 0, 50, 200, or 800 ppm Perc for 6 h/day, 5 days/week, for 13 weeks. The only effect related to treatment was in the flash evoked potential (FEP-V), recorded from the visual cortex. The longer latency potentials (N3) of the FEP-V had a greater amplitude in the 800 ppm Perc group. The FEP-Vs were of normal shape and latency. Although mild neurotoxicity could not be ruled out completely, amplitude changes in N3 can occur for a variety of psychophysiological reasons other than neurotoxicity. Consequently, as a stand-alone finding, the toxicologic significance of the larger FEP in the 800 ppm exposure group was unknown. Other data did not support a diagnosis of neurotoxicity. No treatment-related alterations were noted in expanded clinical observations, in the FEP recorded from the cerebellum (as opposed to visual cortex FEP-V), or in auditory, somatosensory, or caudal nerve evoked potentials. No treatment-related lesions were noted during histopathologic examination of eyes, optic nerves, optic tract, or multiple sections of brain, spinal cord, peripheral nerves, or limb muscles. The no-observed-effect-level (NOEL) was 200 ppm, based on increased amplitude of the longer latency potentials of the FEP at 800 ppm. PMID:9511173

Mattsson, J L; Albee, R R; Yano, B L; Bradley, G; Spencer, P J

240

Public health assessment for Newton County Wells (a/k/a Silver Creek TCE), Joplin, Jasper County, Missouri, Region 7: CERCLIS number MOD985798339. Final report  

SciTech Connect

The Newton County TCE site contains an uncontrolled groundwater plume of trichloroethylene (TCE) contamination. The source of contamination is believed to be FAG Bearings. From 1973 to 1982, FAG Bearings produced ball bearings using TCE as a commercial degreaser. It is alleged that improper disposal and leaks of an alleged closed system of TCE led to the contamination of soil at the industrial site, the groundwater aquifer, and subsequently, 82 private water wells. Exposure pathways at the site consist of inhalation of, ingestion of, and dermal contact with TCE-contaminated groundwater and surface water. Because completed and potential exposure pathways exist, the Newton County TCE site has been classified as a Public Health Hazard.

NONE

1999-07-19

241

Use of statistical tools to evaluate the reductive dechlorination of high levels of TCE in microcosm studies.  

PubMed

A large, multi-laboratory microcosm study was performed to select amendments for supporting reductive dechlorination of high levels of trichloroethylene (TCE) found at an industrial site in the United Kingdom (UK) containing dense non-aqueous phase liquid (DNAPL) TCE. The study was designed as a fractional factorial experiment involving 177 bottles distributed between four industrial laboratories and was used to assess the impact of six electron donors, bioaugmentation, addition of supplemental nutrients, and two TCE levels (0.57 and 1.90 mM or 75 and 250 mg/L in the aqueous phase) on TCE dechlorination. Performance was assessed based on the concentration changes of TCE and reductive dechlorination degradation products. The chemical data was evaluated using analysis of variance (ANOVA) and survival analysis techniques to determine both main effects and important interactions for all the experimental variables during the 203-day study. The statistically based design and analysis provided powerful tools that aided decision-making for field application of this technology. The analysis showed that emulsified vegetable oil (EVO), lactate, and methanol were the most effective electron donors, promoting rapid and complete dechlorination of TCE to ethene. Bioaugmentation and nutrient addition also had a statistically significant positive impact on TCE dechlorination. In addition, the microbial community was measured using phospholipid fatty acid analysis (PLFA) for quantification of total biomass and characterization of the community structure and quantitative polymerase chain reaction (qPCR) for enumeration of Dehalococcoides organisms (Dhc) and the vinyl chloride reductase (vcrA) gene. The highest increase in levels of total biomass and Dhc was observed in the EVO microcosms, which correlated well with the dechlorination results. PMID:22366331

Harkness, Mark; Fisher, Angela; Lee, Michael D; Mack, E Erin; Payne, Jo Ann; Dworatzek, Sandra; Roberts, Jeff; Acheson, Carolyn; Herrmann, Ronald; Possolo, Antonio

2012-02-10

242

Remediation of TCE-contaminated groundwater using zero valent iron and direct current: experimental results and electron competition model  

NASA Astrophysics Data System (ADS)

The objectives of this study are to design an optimal electro-enhanced permeable reactive barrier (E2PRB) system for the remediation of trichloroethylene (TCE)-contaminated water using zero valent iron (ZVI) and direct current (DC) and to investigate the mechanisms responsible for TCE degradation in different ZVI-DC configurations. A series of column experiments was conducted to evaluate the effect of different arrangements of electrodes and ZVI barriers in the column on the TCE removal capacity (RC). In twelve different combinations of ZVI and/or DC application in the test columns, the rate of reductive dechlorination of TCE was improved up to six times with simultaneous application of ZVI and DC compared to that using ZVI only. The most effective arrangement of electrode and ZVI for TCE removal was the column set with ZVI and a cathode installed at the down gradient. Based on the electrokinetic study for the column systems with only DC input, single acid front movement could explain different RCs. An enhanced dechlorination rate of TCE using E2PRB systems, compared to a conventional PRB system, was observed, and is considered to be attributed to more electron sources: (1) external DC, (2) electrolysis of water, (3) oxidation of ZVI, (4) oxidation of dissolved Fe2+, (5) oxidation of molecular hydrogen at the cathode, and (6) oxidation of Fe2+ in mineral precipitates. Each of these electron sources was evaluated for their potential influencing the TCE RC through the electron competition model and energy consumption. A strong correlation between the quantity of electrons generated, RC, and the energy-effectiveness was found.

Moon, Ji-Won; Moon, Hi-Soo; Kim, Heonki; Roh, Yul

2005-09-01

243

Use of statistical tools to evaluate the reductive dechlorination of high levels of TCE in microcosm studies  

NASA Astrophysics Data System (ADS)

A large, multi-laboratory microcosm study was performed to select amendments for supporting reductive dechlorination of high levels of trichloroethylene (TCE) found at an industrial site in the United Kingdom (UK) containing dense non-aqueous phase liquid (DNAPL) TCE. The study was designed as a fractional factorial experiment involving 177 bottles distributed between four industrial laboratories and was used to assess the impact of six electron donors, bioaugmentation, addition of supplemental nutrients, and two TCE levels (0.57 and 1.90 mM or 75 and 250 mg/L in the aqueous phase) on TCE dechlorination. Performance was assessed based on the concentration changes of TCE and reductive dechlorination degradation products. The chemical data was evaluated using analysis of variance (ANOVA) and survival analysis techniques to determine both main effects and important interactions for all the experimental variables during the 203-day study. The statistically based design and analysis provided powerful tools that aided decision-making for field application of this technology. The analysis showed that emulsified vegetable oil (EVO), lactate, and methanol were the most effective electron donors, promoting rapid and complete dechlorination of TCE to ethene. Bioaugmentation and nutrient addition also had a statistically significant positive impact on TCE dechlorination. In addition, the microbial community was measured using phospholipid fatty acid analysis (PLFA) for quantification of total biomass and characterization of the community structure and quantitative polymerase chain reaction (qPCR) for enumeration of Dehalococcoides organisms (Dhc) and the vinyl chloride reductase (vcrA) gene. The highest increase in levels of total biomass and Dhc was observed in the EVO microcosms, which correlated well with the dechlorination results.

Harkness, Mark; Fisher, Angela; Lee, Michael D.; Mack, E. Erin; Payne, Jo Ann; Dworatzek, Sandra; Roberts, Jeff; Acheson, Carolyn; Herrmann, Ronald; Possolo, Antonio

2012-04-01

244

Pilot-scale demonstration of surfactant-enhanced PCE solubilization at the Bachman Road site. 1. Site characterization and test design.  

PubMed

A pilot-scale demonstration of surfactant-enhanced aquifer remediation (SEAR) was conducted to recover dense nonaqueous phase liquid (DNAPL) tetrachloroethene (PCE) from a sandy glacial outwash aquifer underlying a former dry cleaning facility at the Bachman Road site in Oscoda, MI. Part one of this two-part paper describes site characterization efforts and a comprehensive approach to SEAR test design, effectively integrating laboratory and modeling studies. Aquifer coring and drive point sampling suggested the presence of PCE-DNAPL in a zone beneath an occupied building. A narrow PCE plume emanating from the vicinity of this building discharges into Lake Huron. The shallow unconfined aquifer, characterized by relatively homogeneous fine-medium sand deposits, an underlying clay layer, and the absence of significant PCE transformation products, was judged suitable for the demonstration of SEAR. Tween 80 was selected for application based upon its favorable solubilization performance in batch and two-dimensional sand tank treatability studies, biodegradation potential, and regulatory acceptance. Three-dimensional flow and transport models were employed to develop a robust design for surfactant delivery and recovery. Physical and fiscal constraints led to an unusual hydraulic design, in which surfactant was flushed across the regional groundwater gradient, facilitating the delivery of concentrations of Tween 80 exceeding 1% (wt) throughout the treatment zone. The potential influence of small-scale heterogeneity on PCE-DNAPL distribution and SEAR performance was assessed through numerical simulations incorporating geostatistical permeability fields based upon available core data. For the examined conditions simulated PCE recoveries ranged from 94to 99%. The effluent treatment system design consisted of low-profile air strippers coupled with carbon adsorption to trap off-gas PCE and discharge of treated aqueous effluent to a local wastewater treatment plant. The systematic and comprehensive design methodology described herein may serve as a template for application at other DNAPL sites. PMID:15819238

Abriola, Linda M; Drummond, Chad D; Hahn, Ernest J; Hayes, Kim F; Kibbey, Tohren C G; Lemke, Lawrence D; Pennell, Kurt D; Petrovskis, Erik A; Ramsburg, C Andrew; Rathfelder, Klaus M

2005-03-15

245

Potential for Methanotroph-Mediated Natural Attenuation of TCE in a Basalt Aquifer  

NASA Astrophysics Data System (ADS)

Methanotrophic bacteria are one of the microbial communities believed to be responsible for natural attenuation of a trichloroethylene (TCE) plume in the Snake River Plain Aquifer (SRPA). To better understand the role that indigenous methanotrophs may have in TCE degradation in the aquifer, groundwater was collected from four SRPA wells and analyzed for geochemical properties and methanotroph diversity. Dissolved methane concentrations in the aquifer ranged from 1 to >1000 nM. Stable carbon isotope ratios for dissolved methane suggest a microbial source for the methane (del 13C values of ca. -61 per mil in three wells). The combination of 13C enriched methane and 13C depleted-dissolved inorganic carbon in one of the wells suggests that microbial oxidation of methane occurs. Filtered groundwater yielded microorganisms that were used as inocula for enrichments or were frozen and subsequently extracted for DNA. Primers that target taxonomic (type I and type II 16S rDNA) or functional (mmoX and pmoA methane monooxygenase subunits) genes were used to characterize the indigenous methanotrophs via PCR, cloning, and sequencing. DNA sequencing and alignment results suggest that clones with sequences most similar to Methylocystis sp. (a type II methanotroph) and Methylobacter sp. (a type I methanotroph) are frequently present in filtered groundwater with the former often represented in enrichment cultures as well. Methanotroph genes are detected in the aquifer even in wells having methane concentrations as low as 1 nM. Methanotroph presence and a microbial origin for the dissolved methane indicate that microbial cycling of this key gas may play a role in the destruction of TCE in the aquifer.

Colwell, F. S.; Newby, D. T.; Reed, D. W.; Igoe, A.; Petzke, L.; Delwiche, M. E.; McKinley, J. P.; Roberto, F. F.; Whiticar, M. J.

2002-12-01

246

Simulating the fate and transport of TCE from groundwater to indoor air.  

PubMed

This work provides an exploratory analysis on the relative importance of various factors controlling the fate and transport of volatile organic contaminants (in this case, TCE) from a DNAPL source zone located below the water table and into the indoor air. The analysis is conducted using the multi-phase compositional model CompFlow Bio, with the base scenario problem geometry reminiscent of a field experiment conducted by Rivett [Rivett, M.O., (1995), Soil-gas signatures from volatile chlorinated solvents: Borden field experiments. Groundwater, 33(1), 84-98.] at the Borden aquifer where groundwater was observed to transport a contaminant plume a substantial distance without vertical mass transport of the contaminant across the capillary fringe and into the vadose zone. Results for the base scenario model indicate that the structure of the permeability field was largely responsible for deflecting the groundwater plume upward towards the capillary fringe, permitting aqueous phase diffusion to transport the TCE into the vadose zone. Alternative permeability realizations, generated as part of a Monte Carlo simulation process, at times deflected the groundwater plume downwards causing the extended thickness of the saturated zone to insulate the vadose zone from exposure to the TCE by upward diffusive transport. Comparison of attenuation coefficients calculated using the CompFlow Bio and Johnson and Ettinger [Johnson, P.C. and Ettinger, R.A., (1991), Heuristic model for predicting the intrusion rate of contaminant vapors into buildings. Environmental Science and Technology, 25, 1445-1452.] heuristic model exhibited fortuitous agreement for the base scenario problem geometry, with this agreement diverging for the alternative permeability realizations as well as when parameters such as the foundation slab fracture aperture, the indoor air pressure drop, the capillary fringe thickness, and the infiltration rate were varied over typical ranges. PMID:19525028

Yu, Soonyoung; Unger, Andre J A; Parker, Beth

2009-05-08

247

Preliminary study of propyl bromide exposure among New Jersey dry cleaners as a result of a pending ban on perchloroethylene.  

PubMed

Many states are considering, and some states have actively pursued, banning the use of perchloroethylene (PERC) in dry cleaning establishments. Proposed legislation has led many dry cleaners to consider the use of products that contain greater than 90% n-propyl bromide (n-PB; also called 1-bromopropane or 1-BP). Very little information is known about toxicity and exposure to n-PB. Some n-PB-containing products are marketed as nonhazardous and "green" or "organic." This has resulted in some users perceiving the solvent as nontoxic and has resulted in at least one significant poisoning incident in New Jersey. In addition, many dry cleaning operators may not realize that the machine components and settings must be changed when converting from PERC to n-PB containing products. Not performing these modifications may result in overheating and significant leaks in the dry cleaning equipment. A preliminary investigation was conducted of the potential exposures to n-PB and isopropyl bromide (iso-PB; also called 2-bromopropane or 2-BP) among dry cleaners in New Jersey who have converted their machines from PERC to these new solvent products. Personal breathing zone and area samples were collected using the National Institute for Occupational Safety and Health Sampling and Analytical Method 1025, with a slight modification to gas chromatography conditions to facilitate better separation of n-PB from iso-PB. During the preliminary investigation, exposures to n-PB among some workers in two of three shops were measured that were greater than the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for n-PB. The highest exposure measured among a dry cleaning machine operator was 54 parts per million (ppm) as an 8-hr time-weighted average, which is more than 5 times the ACGIH TLV of 10 ppm. The preliminary investigation also found that the work tasks most likely to result in the highest short-term exposures included the introduction of solvent to the machine, maintenance of the machine, unloading and handling of recently cleaned clothes, and interrupting the wash cycle of the machine. In addition, this assessment suggested that leaks may have contributed to exposure and may have resulted from normal machine wear over time, ineffective maintenance, and from the incompatibility of n-PB with gasket materials. PMID:20863050

Blando, James D; Schill, Donald P; De La Cruz, Mary Pauline; Zhang, Lin; Zhang, Junfeng

2010-09-01

248

Solar light induced degradation of trichloroethylene (TCE) using TiO2: effects of solar light intensity and seasonal variations.  

PubMed

The feasibility of the trichloroethylene (TCE) degradation using solar light was investigated. With both solar light and TiO2 present, TCE was more effectively degraded than either with solar light or TiO2 alone. The rate of photocatalytic degradation under a clear sky was about five and 18 times higher than that of photocatalytic degradation under cloudy and thick cloudy skies, respectively. The optimization of the degradation rates was strongly dependent on the solar light intensity. All experimental data were fit to a first-order rate equation. Summer showed faster degradation rate than winter. From the mass balance, this study showed that over 80% of chloride in clear and partly cloudy skies was mineralized from TCE degradation. PMID:12940492

Park, Jaehong; Choi, Euiso; Cho, Il-Hyoung; Kim, Young-Gyu

2003-09-01

249

Phylogenetic Microarray Analysis of a Microbial Community Performing Reductive Dechlorination at a TCE-contaminated Site  

PubMed Central

A high-density phylogenetic microarray (PhyloChip) was applied to track bacterial and archaeal populations through different phases of remediation at Ft. Lewis, WA, a trichloroethene (TCE)-contaminated groundwater site. Biostimulation with whey, and bioaugmentation with a Dehalococcoides-containing enrichment culture were strategies implemented to enhance dechlorination. As a measure of species richness, over 1300 operational taxonomic units (OTUs) were detected in DNA from groundwater samples extracted during different stages of treatment and in the bioaugmentation culture. In order to determine active members within the community, 16S rRNA from samples were analyzed by microarray and ~600 OTUs identified. A cDNA clone library of the expressed 16S rRNA corroborated the observed diversity and activity of some of the phyla. Principle component analysis of the treatment plot samples revealed that the microbial populations were constantly changing during the course of the study. Dynamic analysis of the archaeal population showed significant increases in methanogens at the later stages of treatment that correlated with increases in methane concentrations of over two orders of magnitude. Overall, the PhyloChip analyses in this study have provided insights into the microbial ecology and population dynamics at the TCE-contaminated field site useful for understanding the in situ reductive dechlorination processes.

Lee, Patrick K. H.; Warnecke, F.; Brodie, Eoin L.; Macbeth, Tamzen W.; Conrad, Mark E.; Andersen, Gary L.; Alvarez-Cohen, Lisa

2012-01-01

250

In Situ Chemical Reduction of Aquifer Sediments: Enhancement of Reactive Iron Phases and TCE Dechlorination  

SciTech Connect

In situ chemical reduction of aquifer sediments is currently being used for chromate and TCE remediation by forming a permeable reactive barrier. The chemical and physical processes that occur during abiotic reduction of natural sediments by sodium dithionite were investigated. In different aquifer sediments, 15 to 25% of Fe{sup III} -oxides were dissolved/reduced, which produces primarily adsorbed Fe{sup II}, and some siderite. The sediment reduction rate ({approx} 5h) was the chemically controlled (58 kJ/mole) reduction of a minor phase (<20%). It was necessary to maintain neutral to high pH to maintain reduction efficiency and prevent iron mobilization, as reduction generated H{sup +}. Sequential extractions on reduced sediment showed that adsorbed ferrous iron and iron oxides on the clay size fraction controlled TCE reactivity, and not structural ferrous iron in clay. The mass and rate of field-scale reduction of aquifer sediments were generally predicted with laboratory data using a single reduction reaction.

Szecsody, Jim E.; Fruchter, Jonathan S.; Williams, Mark D.; Vermeul, Vince R.; Sklarew, Debbie S.

2004-07-29

251

Biodegradation of TCE Improved with Lactate Injection in Deep, Fractured Rock  

SciTech Connect

After a recent one-year field evaluation, in situ biodegradation enhanced with the injection of lactate was selected by U.S. Environmental Protection Agency’s (EPA) Region 10, Idaho Department of Environmental Quality, and U.S. Department of Energy for use in a deep, fractured rock aquifer at the Idaho National Engineering and Environmental Laboratory’s (INEEL) Test Area North (TAN). The enhanced biodegradation will replace the default pump-and-treat remedy for the residual source area of a large trichloroethylene (TCE) plume. The field evaluation was conducted as part of an innovative technology evaluation process specified in the site Record of Decision. Five innovative technologies–enhanced in situ biodegradation, in situ chemical oxidation, metal enhanced reductive dechlorination, monolithic confinement, and natural attenuation–were evaluated in this process. Based on initial evaluation and bench-scale testing, biodegradation was selected for evaluation in the residual source area, where nonaqueous TCE is present in a sludge mixture due to the historical injection of waste into the basalt aquifer.

Sorenson, Kent Soren

2000-12-01

252

Acute Exposure to Perchlorethylene alters Rat Visual Evoked Potentials in Relation to Brain Concentration  

EPA Science Inventory

These experiments sought to establish a dose-effect relationship between the concentration of perchloroethylene (PCE) in brain tissue and concurrent changes in visual function. A physiologically-based pharmacokinetic (PBPK) model was implemented to predict concentrations of PCE ...

253

Experimental demonstration of an OpenFlow/PCE integrated control plane for IP over translucent WSON with the assistance of a per-request-based dynamic topology server.  

PubMed

To mitigate the potential scalability issues of an OpenFlow-based control plane, a seamless OpenFlow and Path Computation Element (PCE) integrated control plane is proposed, by means of an architecture in which the path computation function is formally decoupled from the controller so the controller can off-load the task to one or more dedicated PCEs using an open and standard interface and protocol, and where the PCE obtains its topology database by means of a dedicated dynamic topology server, which is accessed by the PCE on a per-request basis. The overall feasibility and performance metrics of this integrated control plane are experimentally verified and quantitatively evaluated on a real IP over translucent Wavelength Switched Optical Network (WSON) testbed. PMID:23481952

Liu, Lei; Casellas, Ramon; Tsuritani, Takehiro; Morita, Itsuro; Martínez, Ricardo; Muñoz, Raül

2013-02-25

254

Combined zero- and first-order kinetic model of the degradation of TCE and cis-DCE with commercial iron  

SciTech Connect

The design of a permeable iron wall depends to a great extent on the transformation kinetics of the chlorinated compounds. Therefore these degradation kinetics of TCE and cis-DCE with commercial iron and their dependence on the properties of the compounds and on the experimental conditions were studied in mixed-batch and column experiments. Since their data cannot sufficiently be described by a pseudo-first-order kinetics, the authors successfully applied an enhanced model accounting for both zero- and first-order kinetics. The fitted kinetic parameters, however, were found to depend on the experimental conditions and compound properties, which is interpreted in terms of different rate-limiting processes. The zero-order rate constant turned out to be twice as high for cis-DCE as for TCE in both experimental systems. Despite its slower transformation without transport control, the first-order rate constant was about 4 times higher for TCE than for cis-DCE in the mixed-batch vials. The authors attribute this to the lower water solubility and thus higher sorptivity of TCE at the polished iron surface. In the column experiments, transformation without transport control was twice as fast as in the batch experiments for both compounds. cis-DCE was degraded faster than TCE in the zero- and first-order region. At higher influent concentrations, the zero- and first-order rate constant of TCE decreased, which they assume to be due to the buildup of iron oxides, and transport to the reactive sites was found to depend a little on flow velocity. Due to the slow first-order kinetics of both compounds, they assume diffusion within micropores to be rate-limiting in flow-through systems. These variations in the kinetic parameters of the combined zero- and first-order model suggest that transport and sorption to reactive sites contribute to kinetic control of the degradation of chlorinated ethenes in addition to charge-transfer processes.

Wuest, W.F.; Koeber, R.; Schlicker, O.; Dahmke, A.

1999-12-01

255

Use of gene probes to assess the impact and effectiveness of aerobic in situ bioremediation of TCE  

SciTech Connect

Gene probe hybridization was used to determine distribution and expression of co-metabolic genes at a contaminated site as it underwent in situ methanotrophic bioremediation of trichloroethylene (TCE). The bioremediation strategies tested included a series of air, air:methane, and air:methane:nutrient pulses of the test plot using horizontal injection wells. During the test period, the levels of TCE reduced drastically in almost all test samples. Sediment core samples (n = 367) taken from 0 m (surface)-43 m depth were probed for gene coding for methanotrophic soluble methane monooxygenase (sMMO) and heterotrophic toluene dioxygenase (TOD), which are known to co-metabolize TCE. The same sediment samples were also probed for genes coding for methanol dehydrogenase (MDH) (catalyzing the oxidation of methanol to formaldehyde) to assess specifically changes in methylotrophic bacterial populations in the site. Gene hybridization results showed that the frequency of detection of sMMO genes were stimulated approximately 250% following 1% methane:air (v/v) injection. Subsequent injection of 4% methane:air (v/v) resulted in an 85% decline probably due to nutrient limitations, since addition of nutrients (gaseous nitrogen and phosphorus) thereafter caused an increase in the frequency of detection of sMMO genes. Detection of TOD genes declined during the process, and eventually they were non-detectable by the final treatment, suggesting that methanotrophs displaced the TOD gene containing heterotrophs. Active transcription of sMMO and TOD was evidenced by hybridization to mRNA. These analyses combined with results showing the concomitant decline in TCE concentrations, increases in chloride concentration and increases in methanotroph viable counts, provide multiple lines of evidence that TCE remediation was caused specifically by methanotrophs. Our results suggest that sMMO genes are responsible for most, if not all, of the observed biodegradation of TCE. This study demonstrates that the use of nucleic acid analytical methods provided a gene specific assessment of the effects of in situ treatment technologies.

Hazen, Terry C.; Chakraborty, Romy; Fleming, James M.; Gregory, Ingrid R.; Bowman, John P.; Jimenez, Luis; Zhang, Dai; Pfiffner, Susan M.; Brockman, Fred J.; Sayler, Gary S.

2009-03-15

256

Use of gene probes to assess the impact and effectiveness of aerobic In situ bioremediation of TCE.  

SciTech Connect

Gene probe hybridization was used to determine distribution and expression of co-metabolic genes at a contaminated site as it underwent in situ methanotrophic bioremediation of trichloroethylene (TCE). The bioremediation strategies tested consisted of a series of air, air:methane, and air:methane:nutrient pulses using a horizontal injection well. Sediment core samples (n=367) taken from 0 (surface)-43m depth were probed for genes coding for soluble methane monooxygenase (sMMO) and toluene dioxygenase (TOD), which are known to cometabolize TCE. The same samples were also probed for genes coding for methanol dehydrogenase (MDH) to access changes in methylotrophic bacterial populations. Hybridization results showed that the frequency of detection of sMMO genes were stimulated approximately 250% following 1% methane:air (v/v) injection. Subsequent 4% methane:air (v/v) injection resulted in an 85% decline probably due to nutrient limitations, since subsequent addition of nutrients (gaseous nitrogen and phosphorus) caused an increase in the frequency of detection of sMMO genes. Detection of TOD genes declined during the process becoming non-detectable by the final treatment. These patterns indicate methanotrophs displaced heterotrophs containing TOD genes. Active transcription of sMMO and TOD was evidenced by hybridization to mRNA. These analyses combined with studies showing the concomitant decline in TCE concentrations, increases in methanotroph viable counts, increased mineralization rates of TCE, and increases in chloride inventories provide multiple lines of evidence that TCE remediation was caused specifically by methanotrophs. This work suggests that sMMO genes are responsible for most, if not all, of the biodegradation of TCE observed. This study demonstrated that the use of nucleic acid analytical methods provided a gene specific assessment of the effects of in situ treatment technologies.

Hazen, Terry C.; Chakraborty, Romy; Fleming, James M.; Gregory, Ingrid R.; Bowman, John P.; Jimenez, Luis; Zhang, Dai; Pfiffner, Susan M.; Brockman, Fred J.; Sayler, Gary S.

2009-03-01

257

Different activity levels of Dehalococcoides mccartyi revealed by FISH and CARD-FISH under non-steady and pseudo-steady state conditions.  

PubMed

A mixed culture capable of dechlorinating perchloroethylene (PCE) to ethene was analyzed under non steady and pseudo-steady state conditions. Dehalococcoides mccartyi, considered to be the primary dechlorinating bacterium able to completely degrade chlorinated hydrocarbons to non toxic ethene, could be detected by CAtalyzed Reporter Deposition Fluorescence In Situ Hybridization (CARD-FISH) since the beginning of culture operation but highlighted by conventional FISH only during active PCE dechlorination to ethene and vinyl chloride (VC). Data generated from FISH and CARD-FISH analyses were compared to those generated from applying PCR-based techniques directed at defining cell abundances (Real Time PCR, qPCR) and assessing cell activities (Reverse Transcription qPCR, RT-qPCR) of Dehalococcoides strains involved in the PCE reductive dechlorination (RD) process. qPCR targeting reductive dehalogenase genes coding for enzymes involved in the individual steps of the RD process, showed that Dehalococcoides strains carrying the tceA gene dominated the community. This observation was consistent with PCE conversion products detected under pseudo-steady state (ethene and VC production), since this tceA gene is known to be associated to strains capable of reducing chlorinated solvents beyond 1,2-cis-dichloroethene (cis-DCE). In line with the FISH data, Dehalococcoides 16S rRNA and tceA genes were expressed only during pseudo-steady state conditions when PCE was converted completely to the final metabolic product ethene. Furthermore, Dehalococcoides cell abundances estimated by CARD-FISH correlated positively with their 16SrRNA gene copy numbers quantified by qPCR. This is consistent with the ability of both these methods to estimate total Dehalococcoides cell numbers including those with low metabolic activities. Thus, this study shows that application potential of FISH analysis to quantify rapidly and efficiently only active dechlorinators in complex communities. PMID:23917146

Matturro, Bruna; Tandoi, Valter; Rossetti, Simona

2013-08-01

258

Efficient Bayesian updating with PCE-based particle filters based on polynomial chaos expansion and CO2 storage  

NASA Astrophysics Data System (ADS)

Underground flow systems, such as oil or gas reservoirs and CO2 storage sites, are an important and challenging class of complex dynamic systems. Lacking information about distributed systems properties (such as porosity, permeability,...) leads to model uncertainties up to a level where quantification of uncertainties may become the dominant question in application tasks. History matching to past production data becomes an extremely important issue in order to improve the confidence of prediction. The accuracy of history matching depends on the quality of the established physical model (including, e.g. seismic, geological and hydrodynamic characteristics, fluid properties etc). The history matching procedure itself is very time consuming from the computational point of view. Even one single forward deterministic simulation may require parallel high-performance computing. This fact makes a brute-force non-linear optimization approach not feasible, especially for large-scale simulations. We present a novel framework for history matching which takes into consideration the nonlinearity of the model and of inversion, and provides a cheap but highly accurate tool for reducing prediction uncertainty. We propose an advanced framework for history matching based on the polynomial chaos expansion (PCE). Our framework reduces complex reservoir models and consists of two main steps. In step one, the original model is projected onto a so-called integrative response surface via very recent PCE technique. This projection is totally non-intrusive (following a probabilistic collocation method) and optimally constructed for available reservoir data at the prior stage of Bayesian updating. The integrative response surface keeps the nonlinearity of the initial model at high order and incorporates all suitable parameters, such as uncertain parameters (porosity, permeability etc.) and design or control variables (injection rate, depth etc.). Technically, the computational costs for constructing the response surface depend on the number of parameters and the expansion degree. Step two consists of Bayesian updating in order to match the reduced model to available measurements of state variables or other past or real-time observations of system behavior (e.g. past production data or pressure at monitoring wells during a certain time period). In step 2 we apply particle filtering on the integrative response surface constructed at step one. Particle filtering is a strong technique for Bayesian updating which takes into consideration the nonlinearity of inverse problem in history matching more accurately than Ensemble Kalman filter do. Thanks to the computational efficiency of PCE and integrative response surface, Bayesian updating for history matching becomes an interactive task and can incorporate real time measurements.

Oladyshkin, S.; Class, H.; Helmig, R.; Nowak, W.

2011-12-01

259

Expression of Reductive Dehalogenase Genes in Dehalococcoides ethenogenes Strain 195 Growing on Tetrachloroethene, Trichloroethene, or 2,3Dichlorophenol  

Microsoft Academic Search

Reductive dehalogenase (RD) gene transcript levels in Dehalococcoides ethenogenes strain 195 were investi- gated using reverse transcriptase quantitative PCR during growth and reductive dechlorination of tetrachlo- roethene (PCE), trichloroethene (TCE), or 2,3-dichlorophenol (2,3-DCP). Cells grown with PCE or TCE had high transcript levels (greater than that for rpoB) for tceA, which encodes the TCE RD, pceA, which encodes the PCE

Jennifer M. Fung; Robert M. Morris; Lorenz Adrian; Stephen H. Zinder

2007-01-01

260

Content Instruction through a Foreign Language. A Report on the 1992-1993 TCE Programme. Research and Fieldwork No. 18.  

ERIC Educational Resources Information Center

|This volume of articles is a report from the national teacher in-service development program in teaching content through a foreign language at the Continuing Education Centre of the University of Jyvaskyla, Finland. This publication is mainly in English, because of the basic rationale of the Teaching Content through English (TCE) programme, and…

Rasanen, Anne, Ed.; Marsh, David, Ed.

261

Quantitation of TCE-Induced Radicals in Liver of B6C3Fl Mice In Vivo: An EPR Study.  

National Technical Information Service (NTIS)

The total radicals generated in liver of B6C3Fl mice in vivo following exposure five days per week for 60 days to water, corn oil, or corn oil supplemented with trichloroethylene (TCE) was determined by EPR/spin trapping techniques. The concentration of t...

L. Steel-Goodwin W. Hurtle W. J. Schmidt S. Berty J. Drerup

1996-01-01

262

REVIEW OF INTRINSIC BIOREMEDIATION OF TCE IN GROUNDWATER AT PICATINNY ARSENAL, NEW JERSEY AND ST. JOSEPH, MICHIGAN  

EPA Science Inventory

Reductive dechlorination occurs frequently in large trichloro-ethylene (TCE) plumes. CE is transformed largely to cis-dichloroethylene (cis-DCE), then to vinyl chloride, and finally to compounds that do not contain organic chlorine. his abstract evaluates the rate and extent of n...

263

Abiotic Removal of TCE and cis-DCE by Magnetite under Aerobic Conditions in Ground Water (Maryland)  

EPA Science Inventory

The former Twin Cities Army Ammunition Plant (TCAAP) is located just north of St. Paul, Minnesota. Disposal of chlorinated solvents at the Building102 site on the TCAAP contaminated groundwater in the shallow, unconsolidated sand aquifer with TCE and cis-DCE. Concentrations of ...

264

Application of fluorescent antibody and enzyme-linked immunosorbent assays for TCE and PAH degrading bacteria  

SciTech Connect

Historically, methods used to identify methanotrophic and polyaromatic hydrocarbon-degrading (PAH) bacteria in environmental samples have been inadequate because isolation and identification procedures are time-consuming and often fail to separate specific bacteria from other environmental microorganisms. Methanotrophic bacteria have been isolated and characterized from TCE-contaminated soils (Bowman et al. 1993; Fliermans et al., 1988). Fliermans et al., (1988) and others demonstrated that cultures enriched with methane and propane could cometabolically degrade a wide variety of chlorinated aliphatic hydrocarbons including ethylene; 1,2-cisdichloroethylene (c-DCE); 1,2-trans-dichloroethylene (t-DCE); vinyl chloride (VC); toluene; phenol and cresol. Characterization of select microorganisms in the natural setting is important for the evaluation of bioremediation potential and its effectiveness. This realization has necessitated techniques that are selective, sensitive and easily applicable to soils, sediments, and groundwater (Fliermans, et al., 1994). Additionally these techniques can identify and quantify microbial types in situ in real time

Brigmon, R.L.; Franck, M.; Brey, J.; Scott, D.; Lanclos, K.; Fliermans, C.

1996-07-01

265

Electro-enhanced Permeable Reactive Barrier : Optimal Design of PRB System With External Current for Effective TCE Removal From Groundwater  

NASA Astrophysics Data System (ADS)

The objective of this study was to design an optimal electro-enhanced permeable reactive barrier (E2PRB) system for remediation of trichloroethylene (TCE)-contaminated water using zero valent iron (ZVI) and direct current (DC). A series of column experiments were conducted to evaluate the location of Fe0 permeable reactive barrier (PRB) and the effects of electrode arrangement in the column on the TCE removal efficiency and iron corrosion processes. In twelve different combinations of ZVI and/or DC application in the test columns, the rate of reductive dechlorination of TCE was improved with simultaneous application of both ZVI and DC compared to that used ZVI only to evaluate the synergistic effect (SE). The most effective arrangement of electrode and ZVI for TCE removal from simulated groundwater was a column set with ZVI and cathode installed at the down gradient (outlet side). Based on the electrochemical study in the E2PRB system, application of direct current provided external electrons to the system so that the system did not depend entirely on the oxidation of the medium for the reductive dechlorination of TCE. The enhanced dechlorination rate of TCE in ZVI-DC systems is considered to attributed to more generation and fast formation kinetic of electron by following reactions: (1) direct supply of electrons from external DC source (2) the electrolysis of water generating additional electrons at the vicinity of the anode (3) the electro-reduction of the compound by released electrons on the ZVI surfaces by oxidation (4) released electron through oxidation of dissolved ferrous iron, and (5) oxidation of atomic hydrogen at the cathode. The competition between five different electron sources generated from five sources evidently influenced on the TCE removal efficiency, valid lifetime of E2PRB system, and reduction of energy expenditure in both of electrochemical and electrokinetic aspects. The results from a series of experiments with twelve columns showed a trend that removal efficiency was more related to the electrode arrangement, but longevity of ZVI PRB and reduction of energy expenditure to location of ZVI installation.

Moon, J.; Moon, H.; Roh, Y.; Kim, H.; Song, Y.

2002-12-01

266

Degradation of trichloroethylene (TCE) and polychlorinated biphenyls (PCBs) by Fe and Fe-Pd bimetals in the presence of surfactants and cosolvents  

SciTech Connect

Surfactants and cosolvents are being used to enhance the removal of dense non-aqueous phase liquids (DNAPL) such as trichloroethylene (TCE) and polychlorinated biphenyls (PCBS) from contaminated soils. However, the waste surfactant solution containing TCE and PCBs must be treated before it can be disposed. This study evaluated the use of zero-valence iron and palladized iron fillings on the dechlorination of TCE and a PCB congener in a dihexylsulfosuccinate surfactant solution. Batch experimental results indicated that TCE can be rapidly degraded by palladized iron filings with a half-life of 27.4 min. PCB was degraded at a slower rate than TCE with a half-life ranging from 100 min to 500 min as the concentration of surfactant increased. In column flow-through experiments, both TCE and PCBs degrade at an enhanced rate with a half-life about 1.5 and 6 min because of an increased solid to solution ratio in the column than in the batch experiments. Results of this work suggest that Fe-Pd filings may be potentially applicable for ex-situ treatment of TCE and PCBs in the surfactant solutions that are generated during surfactant washing of the contaminated soils.

Gu, B.; Liang, L.; West, O.R. [Oak Ridge National Lab., TN (United States); Cameron, P. [Oak Ridge Research Inst., TN (United States); Davenport, D. [Wisconsin Univ., Madison, WI (United States)

1997-02-01

267

Microbially enhanced dissolution and reductive dechlorination of PCE by a mixed culture: Model validation and sensitivity analysis  

NASA Astrophysics Data System (ADS)

Reductive dechlorination catalyzed by organohalide-respiring bacteria is often considered for remediation of non-aqueous phase liquid (NAPL) source zones due to cost savings, ease of implementation, regulatory acceptance, and sustainability. Despite knowledge of the key dechlorinators, an understanding of the processes and factors that control NAPL dissolution rates and detoxification (i.e., ethene formation) is lacking. A recent column study demonstrated a 5-fold cumulative enhancement in tetrachloroethene (PCE) dissolution and ethene formation (Amos et al., 2009). Spatial and temporal monitoring of key geochemical and microbial (i.e., Geobacter lovleyi and Dehalococcoides mccartyi strains) parameters in the column generated a data set used herein as the basis for refinement and testing of a multiphase, compositional transport model. The refined model is capable of simulating the reactive transport of multiple chemical constituents produced and consumed by organohalide-respiring bacteria and accounts for substrate limitations and competitive inhibition. Parameter estimation techniques were used to optimize the values of sensitive microbial kinetic parameters, including maximum utilization rates, biomass yield coefficients, and endogenous decay rates. Comparison and calibration of model simulations with the experimental data demonstrate that the model is able to accurately reproduce measured effluent concentrations, while delineating trends in dechlorinator growth and reductive dechlorination kinetics along the column. Sensitivity analyses performed on the optimized model parameters indicate that the rates of PCE and cis-1,2-dichloroethene (cis-DCE) transformation and Dehalococcoides growth govern bioenhanced dissolution, as long as electron donor (i.e., hydrogen flux) is not limiting. Dissolution enhancements were shown to be independent of cis-DCE accumulation; however, accumulation of cis-DCE, as well as column length and flow rate (i.e., column residence time), strongly influenced the extent of reductive dechlorination. When cis-DCE inhibition was neglected, the model over-predicted ethene production ten-fold, while reductions in residence time (i.e., a two-fold decrease in column length or two-fold increase in flow rate) resulted in a more than 70% decline in ethene production. These results suggest that spatial and temporal variations in microbial community composition and activity must be understood to model, predict, and manage bioenhanced NAPL dissolution.

Chen, Mingjie; Abriola, Linda M.; Amos, Benjamin K.; Suchomel, Eric J.; Pennell, Kurt D.; Löffler, Frank E.; Christ, John A.

2013-08-01

268

Field performance of air-sparging system for removing TCE from groundwater  

SciTech Connect

The removal of volatile organic compounds from groundwater by air sparging (AS) is well-established, although reliable methods for predicting the time required to reach site closure have not been established. To develop and improved understanding of mass transfer processes that limit AS performance, two extended controlled shutdowns of an operating AS system were performed. Monitoring of TCE concentrations in source zone groundwater indicated tailing and rebound behavior similar to that observed for pump-and-treat systems. A simple two-compartment model provided a reasonable description of the 3-year AS history, using parameters calibrated from data collected during the first shutdown period. Comparison of the calibrated rate constants with parameters estimated from laboratory soil columns suggest that, for the study site, aqueous diffusion to discrete air channels has a stronger influence on system performance than rate-limited desorption. Predictions based on the calibrated model indicated that restoration of the source zone to drinking water standards would require approximately 1 decade for the current AS system.

Rabideau, A.J.; Blayden, J.M.; Ganguly, C. [State Univ. of New York, Buffalo, NY (United States). Dept. of Civil, Structural, and Environmental Engineering

1999-01-01

269

Spectral investigation of the phase-transition behavior in (DOEO)4HgBr4·TCE salt  

NASA Astrophysics Data System (ADS)

Room temperature electrical conductivity of (DOEO)4HgBr4·TCE single crystals measured along the a-direction is of the order of 1 S/cm, while perpendicularly to this direction is almost five orders of magnitude smaller. Besides, on cooling the resistivity increases until a maximum reached around 140 K, becomes metallic in the lower temperature, and finally undergoes an insulating transition around 50 K. To add some new observations and explain these interesting properties of the salt we present extended investigations of its spectral properties. In this paper, we discuss the temperature EPR studies of (DOEO)4HgBr4·TCE salt as well as the evolution of its IR spectra vs. temperature. In particular, the analysis of changes of selected normal modes wavenumbers is discussed. Significant changes of EPR shape and characteristic line splitting were observed. It was shown that possible explanation for the peculiar resistivity of (DOEO)4HgBr4·TCE salt observed at about 140 K relates to the disordering of anions and ethylene groups. Their partial ordering can lead to the observed metallic behavior but cannot prevent further localization at lower temperature.

?api?ski, Andrzej; G?secka, Alicja; Graja, Andrzej; Waplak, Stefan; Ostrowski, Adam; Kotov, Alexander I.

2012-08-01

270

Analysis of flow processes during TCE infiltration in heterogeneous soils at the Savannah River Site, Aiken, South Carolina  

SciTech Connect

Contamination of soils and groundwater from volatile organic compounds (VOCs), such as organic solvents and hydrocarbon fuels, is a problem at many industrial facilities. Key to successfully characterizing, containing, and eventually remediating the contamination is a thorough understanding, based on sound scientific principles, of the complex interplay of physical, chemical, and biological processes in geologic media, which affect the migration and distribution of the contaminants, and their response to remediation operations. This report focusses on physical mechanisms that affect contaminant behavior under the conditions encountered at the Savannah River site (SRS). Although other contaminants are present at the site, for the purpose of this discussion we will restrict ourselves to the processes following a spill and infiltration of trichloroethylene (TCE), which is the main contaminant at the location of the Integrated Demonstration Project. We begin by briefly describing the main physical processes following release of TCE into the subsurface. Subsequently we will present simple engineering models that can help to evaluate contaminant migration processes in a semi-quantitative way. Finally, we will discuss results of detailed numerical simulations of TCE infiltration into a heterogeneous medium consisting of sands and clays. These simulations attempt to shed light on the initial distribution of contaminants at the site prior to the start of remediation operations. We also point out limitations of present numerical modeling capabilities, and identify issues that require further research in order that a realistic description of contaminant behavior in the subsurface may be achieved.

Pruess, K.

1992-06-01

271

Transformation of reactive iron minerals in a permeable reactive barrier (biowall) used to treat TCE in groundwater.  

PubMed

Iron and sulfur reducing conditions generally develop in permeable reactive barrier systems (PRB) constructed to treat contaminated groundwater. These conditions allow formation of FeS mineral phases. FeS readily degrades TCE, but a transformation of FeS to FeS2 could dramatically slow the rate of TCE degradation in the PRB. This study uses acid volatile sulfide (AVS) and chromium reducible sulfur (CRS) as probes for FeS and FeS2 to investigate iron sulfide formation and transformation in a column study and PRB field study dealing with TCE degradation. Solid phase iron speciation shows that most of the iron is reduced and sulfur partitioning measurements show that AVS and CRS coexist in all samples, with the conversion of AVS to CRS being most significant in locations with potential oxidants available. In the column study, 54% of FeS was transformed to FeS2 after 2.4 years. In the field scale PRB, 43% was transformed after 5.2 years. Microscopy reveals FeS, Fe3S4 and FeS2 formation in the column system; however, only pyrite formation was confirmed byX-ray diffraction. The polysulfide pathway is most likely the primary mechanism of FeS transformation in the system, with S0 as an intermediate species formed through H2S oxidation. PMID:18800550

He, Y Thomas; Wilson, John T; Wilkin, Richard T

2008-09-01

272

Persulfate oxidation for in situ remediation of TCE. I. Activated by ferrous ion with and without a persulfate-thiosulfate redox couple.  

PubMed

The objective of the laboratory study is to examine the conditions under which transition metal ions (e.g., ferrous ion, Fe2+) could activate the persulfate anion (S2O8(2)-) to produce a powerful oxidant known as the sulfate free radical (SO4-*) with a standard redox potential of 2.6 V. The SO4-* is capable of destroying groundwater contaminants in situ such as trichloroethylene (TCE). Experiments using Fe2+ as an activator under various molar ratios of S2O8(2)-/Fe2+/TCE in an aqueous system indicated that partial TCE degradation occurred almost instantaneously and then the reaction stalled. Either destruction of SO4-* in the presence of excess Fe2+ or the rapid conversion of all Fe2+ to Fe3+ limited the ultimate oxidizing capability of the system. Sequential addition of Fe2+ in small increments resulted in an increased TCE removal efficiency. Therefore, it appeared that Fe2+ played an important role in generating SO4-*. An observation of oxidation-reduction potential (ORP) variations revealed that the addition of sodium thiosulfate (Na2S2O3) to the ferrous ion activated persulfate system could significantly decrease the strong oxidizing conditions. It was hypothesized that the thiosulfate induced reducing conditions might convert Fe3+ to a lower valence state of Fe2+, making the Fe2+ available to activate persulfate decomposition. The sequential addition of thiosulfate (S2O3(2)-), after the initial stalling of ferrous ion activated persulfate oxidation of TCE, resulted in an improvement in TCE removal. The ferrous ion activated persulfate-thiosulfate redox couple resulted in fairly complete TCE degradation in aqueous systems in a short time frame. In soil slurry systems, TCE degradation was slower in comparison to aqueous systems. PMID:15081762

Liang, Chenju; Bruell, Clifford J; Marley, Michael C; Sperry, Kenneth L

2004-06-01

273

Biobased surfactant-like molecules from organic wastes: the effect of waste composition and composting process on surfactant properties and on the ability to solubilize Tetrachloroethene (PCE).  

PubMed

In this work, four surfactant-like humic acids (HAs) obtained from garden lignocellulose wastes and kitchen food wastes mixed with garden-lignocellulose wastes, both before and after composting, were tested for surfactant properties and the ability to solubilize tetrachloroethene (PCE). The waste-derived HAs showed good surfactant properties, lowering the water surface tension from 74 mN m(-1) to 45.4 +/- 4.4 mN m(-1), with a critical micelle concentration (CMC) of 1.54 +/- 1.68 g L(-1), which is lower than many synthetic ionic surfactants. CMC was affected by both waste origin and composting processes. The addition of food waste and composting reduced CMC by adding alkyl-C (measured by CP MAS 13C NMR) and N- and S-HA contents (amide molecules), so that a multistep regression was found [CMC = 24.6 - 0.189 alkyl C - 2.64 (N + S); R2 = 0.77, P < 0.10, n = 6]. The four HAs solubilized PCE at the rate of 0.18-0.47 g PCE/g aqueous biosurfactant. These results were much higher than those reported in the literature for a commercial HA (0.026 g/g), but they were in line with those measured in this work for nonionic surfactants such as Tween-80 (0.69 g/g) and Triton X-100 (1.08 g/g). PMID:18505006

Quadri, Giorgia; Chen, Xiaosong; Jawitz, James W; Tambone, Fulvia; Genevini, Pierluigi; Faoro, Franco; Adani, Fabrizio

2008-04-01

274

Assessing in situ mineralization of recalcitrant organic compounds in vadose zone sediments using ?13C and 14C measurements  

NASA Astrophysics Data System (ADS)

Few techniques exist to measure the biodegradation of recalcitrant organic compounds such as chlorinated hydrocarbons (CHC) in situ, yet predictions of biodegradation rates are needed for assessing monitored natural attenuation. Traditional techniques measuring O2, CO2, or chemical concentrations (in situ respiration, metabolite and soil air monitoring) may not be sufficiently sensitive to estimate biodegradation rates for these compounds. This study combined isotopic measurements (14C and ?13C of CO2 and ?13C of CHCs) in conjunction with traditional methods to assess in situ biodegradation of perchloroethylene (PCE) and its metabolites in PCE-contaminated vadose zone sediments. CHC, ethene, ethane, methane, O2, and CO2 concentrations were measured over 56 days using gas chromatography (GC). ?13C of PCE, trichloroethylene (TCE) and cis-1,2-dichloroethylene (DCE), ?13C and 14C of vadose zone CO2 and sediment organic matter, and ?13C, 14C, and ?D of methane were measured using a GC-isotope ratio mass spectrometer or accelerator mass spectrometer. PCE metabolites accounted for 0.2% to 18% of CHC concentration suggesting limited reductive dechlorination. Metabolites TCE and DCE were significantly enriched in 13C with respect to PCE indicating metabolite biodegradation. Average ?13C-CO2 in source area wells (-23.5‰) was significantly lower compared to background wells (-18.4‰) indicating CHC mineralization. Calculated CHC mineralization rates were 0.003 to 0.01 mg DCE/kg soil/day based on lower 14C values of CO2 in the contaminated wells (63% to 107% modern carbon (pMC)) relative to the control well (117 pMC). Approximately 74% of the methane was calculated to be derived from in situ CHC biodegradation based on the 14C measurement of methane (29 pMC). 14C-CO2 analyses was a sensitive measurement for quantifying in situ recalcitrant organic compound mineralization in vadose zone sediments for which limited methodological tools exist.

Kirtland, Brian C.; Aelion, C. Marjorie; Stone, Peter A.

2005-01-01

275

Drinking Water Contamination and the Incidence of Leukemia and Non-Hodgkin's Lymphoma.  

PubMed Central

>A study of drinking water contamination and leukemia and non-Hodgkin's lymphoma (NHL) incidence (1979-1987) was conducted in a 75-town study area. Comparing incidence in towns in the highest trichloroethylene (TCE) stratum (>5 microg/l) to towns without detectable TCE yielded an age-adjusted rate ratio (RR) for total leukemia among females of 1.43 (95% CI 1.07-1.90). For females under 20 years old, the RR for acute lymphocytic leukemia was 3.26 (95% CI 1.27-8.15). Elevated RRs were observed for chronic myelogenous leukemia among females and for chronic lymphocytic leukemia among males and females. NHL incidence among women was also associated with the highest TCE stratum (RR = 1.36; 95% CI 1.08-1.70). For diffuse large cell NHL and non-Burkitt's high-grade NHL among females, the RRs were 1.66 (95% CI 1.07-2.59) and 3.17 (95% CI 1.23-8.18), respectively, and 1.59 (95% CI 1.04-2.43) and 1.92 (95% CI 0.54-6.81), respectively, among males. Perchloroethylene (PCE) was associated with incidence of non-Burkitt's high-grade NHL among females, but collinearity with TCE made it difficult to assess relative influences. The results suggest a link between TCE/PCE and leukemia/ NHL incidence. However, the conclusions are limited by potential misclassification of exposure due to lack of individual information on long-term residence, water consumption, and inhalation of volatilized compounds.

Cohn, P; Klotz, J; Bove, F; Berkowitz, M; Fagliano, J

1994-01-01

276

A Dechlorinating Community Resulting From In Situ Biostimulation of a TCE-contaminated Deep Fracture Basalt Aquifer  

SciTech Connect

Sodium lactate additions to a trichloroethene (TCE) residual source area in deep, fractured basalt at a U.S. Department of Energy site have resulted in the enrichment of the indigenous microbial community, the complete dechlorination of nearly all aqueous-phase TCE to ethene, and the continued depletion of the residual source since 1999. The bacterial and archaeal consortia in groundwater obtained from the residual source were assessed by using PCR-amplified 16S rRNA genes. A clone library of bacterial amplicons was predominated by those from members of the class Clostridia (57 of 93 clones), of which a phylotype most similar to that of the homoacetogen Acetobacterium sp. strain HAAP-1 was most abundant (32 of 93 clones). The remaining Bacteria consisted of phylotypes affiliated with Sphingobacteria, Bacteroides, Spirochaetes, Mollicutes, and Proteobacteria and candidate divisions OP11 and OP3. The two proteobacterial phylotypes were most similar to those of the known dechlorinators Trichlorobacter thiogenes and Sulfurospirillum multivorans. Although not represented by the bacterial clones generated with broad-specificity bacterial primers, a Dehalococcoides-like phylotype was identified with genus-specific primers. Only four distinct phylotypes were detected in the groundwater archaeal library, including predominantly a clone affiliated with the strictly acetoclastic methanogen Methanosaeta concilii (24 of 43 clones). A mixed culture that completely dechlorinates TCE to ethene was enriched from this groundwater, and both communities were characterized by terminal restriction fragment length polymorphism (T-RFLP). According to T-RFLP, the laboratory enrichment community was less diverse overall than the groundwater community, with 22 unique phylotypes as opposed to 43 and a higher percentage of Clostridia, including the Acetobacterium population. Bioreactor archaeal structure was very similar to that of the groundwater community, suggesting that methane is generated primarily via the acetoclastic pathway, using acetate generated by lactate fermentation and acetogenesis in both systems.

T. Wood; D. E. Cummings

2004-12-01

277

Comparison Of A Laboratory Consortium That Dechlorinates TCE To Ethene To The Field Community From Which It Was Derived  

SciTech Connect

Sodium lactate additions to a trichloroethene (TCE) residual source area in deep, fractured basalt at a U.S. Department of Energy site have resulted in the enrichment of the indigenous microbial community, the complete dechlorination of nearly all aqueous-phase TCE to ethene, and the continued depletion of the residual source since 1999. The bacterial and archaeal consortia in groundwater obtained from the residual source were assessed by using PCR-amplified 16S rRNA genes. A clone library of bacterial amplicons was predominated by those from members of the class Clostridia (57 of 93 clones), of which a phylotype most similar to that of the homoacetogen Acetobacterium sp. strain HAAP-1 was most abundant (32 of 93 clones). The remaining Bacteria consisted of phylotypes affiliated with Sphingobacteria, Bacteroides, Spirochaetes, Mollicutes, and Proteobacteria and candidate divisions OP11 and OP3. The two proteobacterial phylotypes were most similar to those of the known dechlorinators Trichlorobacter thiogenes and Sulfurospirillum multivorans. Although not represented by the bacterial clones generated with broad-specificity bacterial primers, a Dehalococcoides-like phylotype was identified with genus-specific primers. Only four distinct phylotypes were detected in the groundwater archaeal library, including predominantly a clone affiliated with the strictly acetoclastic methanogen Methanosaeta concilii (24 of 43 clones). A mixed culture that completely dechlorinates TCE to ethene was enriched from this groundwater, and both communities were characterized by terminal restriction fragment length polymorphism (T-RFLP). According to T-RFLP, the laboratory enrichment community was less diverse overall than the groundwater community, with 22 unique phylotypes as opposed to 43 and a higher percentage of Clostridia, including the Acetobacterium population. Bioreactor archaeal structure was very similar to that of the groundwater community, suggesting that methane is generated primarily via the acetoclastic pathway, using acetate generated by lactate fermentation and acetogenesis in both systems.

T. Wood; K. S. Sorenson; D. E. Cummings

2004-12-01

278

Global gene expression of Dehalococcoides within a robust dynamic TCE-dechlorinating community under conditions of periodic substrate supply.  

PubMed

A microarray targeting four sequenced strains in the Dehalococcoides (Dhc) genus was used to analyze gene expression in a robust long-term trichloroethene (TCE)-degrading microbial community (designated ANAS) during feeding cycles that involve conditions of periodic substrate supply. The Dhc transcriptome was examined at three time-points throughout a batch feeding cycle: T1 (27 h) when TCE, dichloroethene (DCE), and vinyl chloride (VC) were present; T2 (54 h) when only VC remained; and T3 (13 days) when Dhc had been starved of substrate for 9 days. Ninety percent of the Dhc open reading frames (ORFs) that were detected in the ANAS DNA were found to be expressed as RNA sometime during the time course, demonstrating extraordinary utilization of the streamlined genome. Ninety-seven percent of these transcripts were differentially expressed during the time course indicating efficiency of transcription through regulation in Dhc. Most Dhc genes were significantly down-regulated at T3 , responding to a lack of substrate as would be expected. The tceA and vcrA genes, which code for proteins with known chlorinated ethene reduction functions, were highly expressed at both T1 and T2 , whereas two other putative reductive dehalogenase genes (DET0173 and DET1545) were most highly expressed at T2 , likely in response to the presence of VC. Hydrogenases were most highly expressed at T1 , reflecting their important role in accumulating electrons used to initiate reductive dechlorination and other biosynthesis pathways. Cobalamin transport genes were preferentially expressed at T2 , reflecting an increase in corrinoid transport as chloroethenes were degraded and a decrease in activity of the transport system after dehalogenation was complete. This is the first application of a microarray targeting a known genus, including both core genomes and identified strain-specific genes, to improve our understanding of transcriptional dynamics within an undefined microbial community. PMID:23280440

West, Kimberlee A; Lee, Patrick K H; Johnson, David R; Zinder, Stephen H; Alvarez-Cohen, Lisa

2013-02-09

279

Fingerprinting TCE Sources and Natural Attenuation Capacity of a Sedimentary Bedrock Aquifer using Compound Specific Isotope Analysis - A Case Study in the City of Guelph, Ontario.  

NASA Astrophysics Data System (ADS)

Chlorinated volatile organic compounds were detected in an industrial facility (site) in the upper part of the underlying dolomite bedrock aquifer. The primary chlorinated solvent detected at the site is trichloroethene (TCE), and associated daughter products, such as cis-1,2- dichloroethene (cis-1,2-DCE) and vinyl chloride (VC), are also present. Several conventional monitoring wells installed at the site were recently sampled for VOCs analysis, inorganic sensitive REDOX parameters and Compound Specific Isotope Analyses (CSIA) of 13C and 37Cl in order to evaluate the natural attenuation capacity of the local upper bedrock aquifer. A municipal well was also included in this study. The municipal well is located approximately 500 meters southwest from the investigated site and consists of anuncased bedrock well completed to 102 meters below ground surface (mbgs). Chlorinated volatile organic compounds were detected in this well during the evaluation of municipal groundwater resources performed in the early 1990s by the City of Guelph. Neither the City nor the Ministry of the Environment of the Province of Ontario (MOE) have been able to satisfactorily determine the origin of these compounds. Groundwater for VOCs analysis and CSIA were therefore collected in the municipal well in order to evaluate the relationship between the TCE detected in the municipal well and the TCE plume detected in the nearby industrial facility. The inorganic data indicated that the local upper aquifer is under sulfate-reducing conditions in some areas where typical VOC's daughter products and highly enriched ?13C and ? 37Cl values of TCE and cis-1,2-DCE were observed. These findings indicated that microbial reductive dechlorination of TCE is occurring in some areas of the local aquifer. The ? 13C values of TCE obtained in groundwater from the conventional wells were approximately 10 ‰ more depleted than ? 13C values obtained for the deep municipal production well. These data indicate that there is no relationship between the TCE plume at the site and the TCE present in the water of the municipal well, suggesting that other potential regional TCE sources are likely to be present in the area.

Lima, P. L.; Aravena, R.; Parker, B. L.; Cherry, J. A.

2009-05-01

280

Efficacy of controlled-release KMnO4 (CRP) for controlling dissolved TCE plume in groundwater: a large flow-tank study.  

PubMed

A well-based, reactive barrier system using controlled-release potassium permanganate (CRP system) was recently developed as a long-term treatment option for dilute plumes of chlorinated solvents in groundwater. In this study, we performed large-scale (L x W x D = 8 m x 4 m x 2 m) flow-tank experiments to examine remedial efficacy of the CRP system. A total of 110 CRP rods (OD x L=5 cm x 150 cm) were used to construct a well-based CRP system (L x W x D = 3 m x 4 m x 1.5 m) comprising three discrete barriers installed at 1-m interval downstream. Natural sands having oxidant demand of 3.7 g MnO(4)(-)kg(-1) for 500 mg L(-1)MnO(4)(-) were used as porous media. After MnO(4)(-) concentrations were somewhat stabilized (0.5-6.0 mg L(-1)), trichloroethylene (TCE) plume was flowed through the flow-tank for 53 d by supplying 1.19 m(3)d(-1) of TCE solution. Mean initial TCE concentrations were 87 microg L(-1) for first 20 d and 172 microg L(-1) for the next 33 d. During TCE treatment, flow velocity (0.60md(-1)), pH (7.0-8.2), and concentrations of dissolved metals ([Al]=0.7 mg L(-1), [Fe]=0.01 mg L(-1)) showed little variations. The MnO(2)(s) contents in the sandy media measured after the TCE treatment ranged from 21 to 26 mg kg(-1), slightly increased from mean baseline value of 17 mg kg(-1). Strengths of the TCE plume considerably diminished by the CRP system. For the 87 microg L(-1) plume, TCE concentrations decreased by 38% (53), 67% (29), and 74% (23 microg L(-1)) after 1st, 2nd, and 3rd barriers, respectively. For the 172 microg L(-1) plume, TCE concentrations decreased by 27% (125), 46% (93), and 65% (61 microg L(-1)) after 1st, 2nd, and 3rd barriers, respectively. Incomplete destruction of TCE plume was attributed to the lack of lateral dispersion in the unpumped well-based barrier system. Development of delivery systems that can facilitate lateral spreading and mixing of permanganate with contaminant plume is warranted. PMID:19118857

Lee, Byung Sun; Kim, Jeong Hee; Lee, Ki Churl; Kim, Yang Bin; Schwartz, Franklin W; Lee, Eung Seok; Woo, Nam Chil; Lee, Myoung Ki

2008-12-31

281

Two types of charge carrier localization centers in (DOEO)4[HgBr4] · TCE single crystals  

NASA Astrophysics Data System (ADS)

Using ESR spectroscopy, it has been found that the additional paramagnetic centers appear in the (DOEO)4[HgBr4] · TCE crystals at temperatures of 5-70 K. The symmetry of their crystal field differs from that observed for charge carriers in a temperature range of 70-300 K. The comparison of the temperature dependences of resistivity with parameters of the ESR spectra makes it possible to assume that the carriers localize at two types of sites differing by the crystalline surrounding at 70 K.

Chernenkaya, A. S.; Koplak, O. V.; Kotov, A. I.; Morgunov, R. B.; Yagubskii, E. B.

2012-12-01

282

Desulfitobacterium sp. strain PCE1, an anaerobic bacterium that can grow by reductive dechlorination of tetrachloroethene or ortho-chlorinated phenols  

Microsoft Academic Search

A strictly anaerobic bacterium, strain PCE1, was isolated from a tetrachloroethene-dechlorinating enrichment culture. Cells\\u000a of the bacterium were motile curved rods, with approximately four lateral flagella. They possessed a gram-positive type of\\u000a cell wall and contained cytochrome c. Optimum growth occurred at pH 7.2–7.8 and 34–38??C. The organism grew with l-lactate, pyruvate, butyrate, formate, succinate, or ethanol as electron donors,

Jan Gerritse; Veronique Renard; Teresa M. Pedro Gomes; Paul A. Lawson; Matthew D. Collins; Jan C. Gottschal

1996-01-01

283

In situ redox manipulation of subsurface sediments from Fort Lewis, Washington: Iron reduction and TCE dechlorination mechanisms  

SciTech Connect

Pacific Northwest National Laboratory (PNNL) conducted a bench-scale study to determine how effective chemically treated Ft. Lewis sediments can degrade trichloroethylene (TCE). The objectives of this experimental study were to quantify: (1) sediment reduction and oxidation reactions, (2) TCE degradation reactions, and (3) other significant geochemical changes that occurred. Sediment reduction and oxidation were investigated to determine the mass of reducible iron in the Ft. Lewis sediments and the rate of this reduction and subsequent oxidation at different temperatures. The temperature dependence was needed to be able to predict field-scale reduction in the relatively cold ({approximately}11 C) Ft. Lewis aquifer. Results of these experiments were used in conjunction with other geochemical and hydraulic characterization to design the field-scale injection experiment and predict barrier longevity. For example, the sediment reduction rate controls the amount of time required for the dithionite solution to fully react with sediments. Sediment oxidation experiments were additionally conducted to determine the oxidation rate and provide a separate measure of the mass of reduced iron. Laboratory experiments that were used to meet these objectives included: (1) sediment reduction in batch (static) systems, (2) sediment reduction in 1-D columns, and (3) sediment oxidation in 1-D columns. Multiple reaction modeling was conducted to quantify the reactant masses and reaction rates.

JE Szecsody; JS Fruchter; DS Sklarew; JC Evans

2000-03-21

284

Final Report on Testing of Off-Gas Treatment Technologies for Abatement of Atmospheric Emissions of Chlorinated Volatile Organic Compounds  

SciTech Connect

The purpose of this report is to summarize the results of the program for off-gas treatment of atmospheric emissions of chlorinated volatile organic compounds (CVOCs), in particular trichloroethylene (TCE) and perchloroethylene (PCE). This program was funded through the Department of Energy Office of Technology Development`s VOC`s in Non-Arid Soils Integrated Demonstration (VNID). The off-gas treatment program was initiated after testing of in-situ air stripping with horizontal wells was completed (Looney et al., 1991). That successful test expectedly produced atmospheric emissions of CVOCs that were unabated. It was decided after that test that an off-gas treatment is an integral portion of remediation of CVOC contamination in groundwater and soil but also because several technologies were being developed across the United States to mitigate CVOC emissions. A single platform for testing off-gas treatment technologies would facilitate cost effective evaluation of the emerging technologies. Another motivation for the program is that many CVOCs will be regulated under the Clean Air Act Amendments of 1990 and are already regulated by many state regulatory programs. Additionally, compounds such as TCE and PCE are pervasive subsurface environmental contaminants, and, as a result, a small improvement in terms of abatement efficiency or cost will significantly reduce CVOC discharges to the environment as well as costs to United States government and industry.

Jarosch, T.R.; Haselow, J.S.; Rossabi, J.; Burdick, S.A.; Raymond, R.; Young, J.E.; Lombard, K.H.

1995-01-23

285

Stripping volatile organic compounds and petroleum hydrocarbons from water by tray aeration  

SciTech Connect

Volatile organic compounds (VOCS) and petroleum products are ubiquitous groundwater contaminants. Petroleum products, e.g., diesel fuel, contain a wide array of volatile, semivolatile, and long chain hydrocarbon compounds. This research sought to determine whether air stripping can provide a site specific treatment solution for petroleum contaminated groundwaters and to document the abilities and limitations of tray type (Shallow Tray) air stripping technology. Full factorial experimental trials were conducted to determine the influence of inlet water flow rate and temperature on trichloroethylene (TCE), perchloroethylene (PCE) and total petroleum hydrocarbon (TPH) removal. As expected, TPH removal controlled air stripper performance, and liquid temperature affected removal more than flow rate. The mass transfer rate of TCE and PCE from water to air was controlled by the compound`s volatility, while the TPH mass transfer rate was controlled by the compound`s concentration gradient. Results indicate that economical air stripping of VOC and TPH compounds can be achieved using low liquid flow rates (20-75 L/min) and medium liquid temperatures (16-28 deg C) in tray type air strippers.

Labranche, D.F.; Collins, M.R.

1997-03-01

286

The Relationship between Multiple Myeloma and Occupational Exposure to Six Chlorinated Solvents  

PubMed Central

Objectives Few studies have examined whether exposure to chlorinated solvents is associated with increased risk of multiple myeloma (MM). Using occupational exposure information, we evaluated associations between the risk of MM and exposure to six chlorinated solvents: 1,1,1-trichloroethane (TCA), trichloroethylene (TCE), methylene chloride (DCM), perchloroethylene (PCE), carbon tetrachloride, and chloroform. Methods MM cases were identified through cancer registries and controls were identified in the general population. In-person interviews obtained lifetime occupational histories and additional information on jobs with likely solvent exposure. We reviewed each job and assigned exposure metrics of probability, frequency, intensity, and confidence using job-exposure matrices modified by job-specific questionnaire information. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations between MM and having ever been exposed to each, and any, chlorinated solvent and also analyzed whether associations varied by duration and cumulative exposure. We also considered all occupations that were given the lowest confidence scores as unexposed and repeated all analyses. Results Risk of MM was significantly elevated for subjects ever exposed to TCA (OR (95% CI): 1.8 (1.1–2.9)). Ever-exposure to TCE or DCM also entailed elevated, but not statistically significant, risks of MM; these became statistically significant when occupations that had low confidence scores were considered unexposed (TCE: 1.7 (1.0–2.7); DCM: 2.0 (1.2–3.2)). Increasing duration and cumulative exposure to TCE were associated with significantly increasing risk of MM when jobs given low confidence were considered unexposed. Increasing cumulative exposure to PCE was also associated with increasing MM risk. We observed non-significantly increased MM risks with exposure to chloroform; however, few subjects were exposed. Conclusions Evidence from this relatively large case-control study suggests that exposures to certain chlorinated solvents may be associated with increased incidence of MM; however, the study is limited by relatively low participation (52%) among controls.

Gold, Laura S; Stewart, Patricia A; Milliken, Kevin; Purdue, Mark; Severson, Richard; Seixas, Noah; Blair, Aaron; Hartge, Patricia; Davis, Scott; De Roos, Anneclaire J

2011-01-01

287

A Three-electrode Column for Pd-Catalytic Oxidation of TCE in Groundwater with Automatic pH-regulation and Resistance to Reduced Sulfur Compound Foiling  

PubMed Central

A hybrid electrolysis and Pd-catalytic oxidation process is evaluated for degradation of trichloroethylene (TCE) in groundwater. A three-electrode, one anode and two cathodes, column is employed to automatically develop a low pH condition in the Pd vicinity and a neutral effluent. Simulated groundwater containing up to 5 mM bicarbonate can be acidified to below pH 4 in the Pd vicinity using a total of 60 mA with 20 mA passing through the third electrode. By packing 2 g of Pd/Al2O3 pellets in the developed acidic region, the column efficiency for TCE oxidation in simulated groundwater (5.3 mg/L TCE) increases from 44 to 59 and 68% with increasing Fe(II) concentration from 0 to 5 and 10 mg/L, respectively. Different from Pd-catalytic hydrodechlorination under reducing conditions, this hybrid electrolysis and Pd-catalytic oxidation process is advantageous in controlling the fouling caused by reduced sulfur compounds (RSCs) because the in situ generated reactive oxidizing species, i.e., O2, H2O2 and •OH, can oxidize RSCs to some extent. In particular, sulfite at concentrations less than 1 mM even greatly increases TCE oxidation by the production of SO4•?, a strong oxidizing radical, and more •OH.

Yuan, Songhu; Chen, Mingjie; Mao, Xuhui; Alshawabkeh, Akram N.

2013-01-01

288

Plume persistence caused by back diffusion from thin clay layers in a sand aquifer following TCE source-zone hydraulic isolation  

Microsoft Academic Search

This paper concludes that back diffusion from one or a few thin clayey beds in a sand aquifer can cause contaminant persistence above MCLs in a sand aquifer long after the source zone initially causing the plume is isolated or removed. This conclusion is based on an intensive case study of a TCE contaminated site in Florida, with the processes

Beth L. Parker; Steven W. Chapman; Martin A. Guilbeault

2008-01-01

289

Multiplexed selective detection and identification of TCE and xylene in water by on-chip absorption spectroscopy  

NASA Astrophysics Data System (ADS)

We demonstrate a device which can do multiplexed detection of two different chemicals on one chip by using infrared absorption spectroscopy. The signature of Trichloroethylene(TCE) and xylene in water enable multiplexed detection on one chip. We use the slow light effect in the photonic crystal design which enhances the absorption of the analytes by a factor of 30 as demonstrated by our previous works. In order to match the absorption peaks of these two analytes, photonic crystal slow light regions are designed at 1644nm and 1674nm with a SU8 cladding on top. Multiplexed detection is enabled by using a multimode interference (MMI) optical power splitter at the input, which divides optical power into two arms, and Y combiner at the output. Consequently, the absorption of these two chemicals can be enhanced by the slow light effect. The MMI structure and Y combiner also enable the multiplexed detection of two analytes on one chip.

Lai, Wei-Cheng; Chakravarty, Swapnajit; Zou, Yi; Chen, Ray T.

2013-03-01

290

MICROSCOPIC OBSERVATION AND QUANTIFICATION OF ENHANCED DNAPL REMOVAL BY COSOLVENT-AIR FLOODING  

EPA Science Inventory

The simultaneous injection of cosolvent and air has been suggested to improve sweep efficiency of cosolvent flooding for dense nonaqueous phase liquid (DNAPL) remediation. Glass micromodel experiments were conducted to investigate the factors that influence perchloroethylene (PCE...

291

Interactions of water contaminants. I. Plasma enzyme activity and response surface methodology following gavage administration of CCl4 and CHCl3 or TCE singly and in combination in the rat  

SciTech Connect

The joint hepatotoxicity of CCl4 and CHCl3 or TCE in male CD rats following simultaneous oral administration has been investigated. Rats with chronic indwelling arterial cannulas were administered a single oral dose of CCl4 and CHCl3 or CCl4 and TCE in 5% Emulphor at doses of 0 to 700 mg/kg. Hepatotoxicity was evaluated by measuring the activity of AST, ALT, and SDH in plasma at 0, 3, 6, 12, 24, 36, 48, and 72 hr postgavage. Response data were analyzed for interaction using response surface methodology. CCl4 alone displayed dose-dependent toxicity. TCE demonstrated little evidence of hepatotoxicity. In combination, both CCl4/CHCl3 and CCl4/TCE displayed a synergistic (supraadditive) response for peak plasma enzyme activity.

Borzelleca, J.F.; O'Hara, T.M.; Gennings, C.; Granger, R.H.; Sheppard, M.A.; Condie, L.W. Jr. (Medical College of Virginia, Richmond (USA))

1990-04-01

292

Degradation of TCE, Cr(VI), sulfate, and nitrate mixtures by granular iron in flow-through columns under different microbial conditions  

Microsoft Academic Search

Flow-through aquifer columns packed with a middle layer of granular iron (Fe0) were used to study the applicability and limitations of bio-enhanced Fe0 barriers for the treatment of contaminant mixtures in groundwater. Concentration profiles along the columns showed extensive degradation of hexavalent chromium Cr(VI), nitrate, sulfate, and trichloroethene (TCE), mainly in the Fe0 layer. One column was bioaugmented with Shewanella

Sumeet Gandhi; Byung-Taek Oh; Jerald L. Schnoor; Pedro J. J. Alvarez

2002-01-01

293

Persulfate oxidation for in situ remediation of TCE. I. Activated by ferrous ion with and without a persulfate–thiosulfate redox couple  

Microsoft Academic Search

The objective of the laboratory study is to examine the conditions under which transition metal ions (e.g., ferrous ion, Fe2+) could activate the persulfate anion (S2O82?) to produce a powerful oxidant known as the sulfate free radical (SO4?) with a standard redox potential of 2.6 V. The SO4? is capable of destroying groundwater contaminants in situ such as trichloroethylene (TCE).

Chenju Liang; Clifford J. Bruell; Michael C. Marley; Kenneth L. Sperry

2004-01-01

294

Tc of 11 K Identified for the Third Polymorph of the (BEDT-TTF)2Ag(CF3)4(TCE) Organic Superconductor  

NASA Astrophysics Data System (ADS)

The crystal structure of the third polymorph of the organic superconductor (BEDT-TTF)2Ag(CF3)4(TCE), where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene and TCE is 1,1,2-trichloroethane, has been investigated. The crystal consists of alternating stacks of two types of donor sheets, ?- and ?\\prime-types. Although this structure is similar to the previously solved two-layered high-Tc phase of (BEDT-TTF)2Ag(CF3)4(TCE), the axis perpendicular to the conducting layer of the unit cell of the new phase is twice as large as that of the two-layered phase; thus, four layers form the repeating unit. Superconductivity is attributed to the ?-type conducting layer, because the ?\\prime-type conducting layer is in an acentric charge-ordered state. The onset superconducting transition temperatures are approximately 11.0 and 9.5 K for the four-layered and two-layered phases, respectively.

Kawamoto, Tadashi; Mori, Takehiko; Nakao, Akiko; Murakami, Youichi; Schlueter, John A.

2012-02-01

295

Determination of partition coefficients for trichloroethanol (TCOH) and chioral hydrate (CH) - two metabolites of trichloroethylene (TCE). Interim report, August 1994-January 1995  

SciTech Connect

Trichioroethylene (TCE), a common groundwater contaminant, has been shown to be carcinogenic in some animal species. To determine the risk in humans, the use of physiologically-based pharmacokinetic models (PBPK) has become increasingly the method of choice. Formerly it was a common practice to calculate risk estimates on the basis of administered dose-toxicity/tumor incidence, it is now recognized that the dose delivered to the target organ is more accurate. Determination of partition coefficients (the solubility of the chemical in tissue) is one element important in the development of the PBPK model. This study focuses on two metabolites of TCE, chloral hydrate (CII) and trichloroethanol (TCOII). All studies were conducted in B6C3F1 mice since this species was used in the NCI/NTP carcinogenicity studies on TCE. Partition coefficients for CII and TCOII were determined using the nonvolatile method of Jepson et al., (Fund. and Appl. Tox 22:1994). Tissues used in CII studies were pre-treated with 20% lead acetate to insure no metabolism occurred during the incubation period.

Seckel, C.; Creech, J.R.; Black, R.K.; Garrity, B.L.

1995-02-01

296

Development of an integrated, in-situ remediation technology. Topical report for task No. 9. Part I. TCE degradation using nonbiological methods, September 26, 1994--May 25, 1996  

SciTech Connect

Contamination in low-permeability soils poses a significant technical challenge for in situ remediation efforts. Poor accessibility to the contaminants and difficulty in delivery of treatment reagents have rendered existing in situ treatments such as bioremediation, vapor extraction, pump and treat rather ineffective when applied to low-permeability soils present at many contaminated sites. The technology is an integrated in situ treatment in which established geotechnical methods are used to install degradation zones directly in the contaminated soil and electro-osmosis is used to move the contaminants back and forth through those zones until the treatment is completed. The present Draft Topical Report for Task No. 9 summarizes laboratory investigations into TCE degradation using nonbiological methods. These studies were conducted by the General Electric Company. The report concentrates on zero valent iron as the reducing agent and presents data on TCE and daughter product degradation rates in batch experiments, column studies, and electroosmotic cells. It is shown that zero valent iron effectively degrades TCE in electroosmotic experiments. Daughter product degradation and gas generation are shown to be important factors in designing field scale treatment zones for the Lasagna{trademark} process.

Shapiro, A.P.; Sivavec, T.M.; Baghel, S.S. [General Electric Research and Development, Schenectady, NY (United States)

1997-04-01

297

Reductive dechlorination of TCE by chemical model systems in comparison to dehalogenating bacteria: insights from dual element isotope analysis (13C/12C, 37Cl/35Cl).  

PubMed

Chloroethenes like trichloroethene (TCE) are prevalent environmental contaminants, which may be degraded through reductive dechlorination. Chemical models such as cobalamine (vitamin B12) and its simplified analogue cobaloxime have served to mimic microbial reductive dechlorination. To test whether in vitro and in vivo mechanisms agree, we combined carbon and chlorine isotope measurements of TCE. Degradation-associated enrichment factors ?(carbon) and ?(chlorine) (i.e., molecular-average isotope effects) were -12.2‰ ± 0.5‰ and -3.6‰ ± 0.1‰ with Geobacter lovleyi strain SZ; -9.1‰ ± 0.6‰ and -2.7‰ ± 0.6‰ with Desulfitobacterium hafniense Y51; -16.1‰ ± 0.9‰ and -4.0‰ ± 0.2‰ with the enzymatic cofactor cobalamin; -21.3‰ ± 0.5‰ and -3.5‰ ± 0.1‰ with cobaloxime. Dual element isotope slopes m = ??(13)C/ ??(37)Cl ? ?(carbon)/?(chlorine) of TCE showed strong agreement between biotransformations (3.4 to 3.8) and cobalamin (3.9), but differed markedly for cobaloxime (6.1). These results (i) suggest a similar biodegradation mechanism despite different microbial strains, (ii) indicate that transformation with isolated cobalamin resembles in vivo transformation and (iii) suggest a different mechanism with cobaloxime. This model reactant should therefore be used with caution. Our results demonstrate the power of two-dimensional isotope analyses to characterize and distinguish between reaction mechanisms in whole cell experiments and in vitro model systems. PMID:23627862

Cretnik, Stefan; Thoreson, Kristen A; Bernstein, Anat; Ebert, Karin; Buchner, Daniel; Laskov, Christine; Haderlein, Stefan; Shouakar-Stash, Orfan; Kliegman, Sarah; McNeill, Kristopher; Elsner, Martin

2013-05-28

298

Tc of 11K Identified for the Third Polymorph of the (BEDT-TTF)(BEDT-TTF){<_2}Ag(CF{<_3}){<_4}(TCE) Organic Superconductor.  

SciTech Connect

The crystal structure of the third polymorph of the organic superconductor (BEDT-TTF){sub 2}Ag(CF{sub 3}){sub 4}(TCE), where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene and TCE is 1,1,2-trichloroethane, has been investigated. The crystal consists of alternating stacks of two types of donor sheets, {Kappa}- and {alpha}-types. Although this structure is similar to the previously solved two-layered high-T{sub c} phase of (BEDT-TTF){sub 2}Ag(CF{sub 3}){sub 4}(TCE), the axis perpendicular to the conducting layer of the unit cell of the new phase is twice as large as that of the two-layered phase; thus, four layers form the repeating unit. Superconductivity is attributed to the {Kappa}-type conducting layer, because the {alpha}-type conducting layer is in an acentric charge-ordered state. The onset superconducting transition temperatures are approximately 11.0 and 9.5 K for the four-layered and two-layered phases, respectively.

Kawamoto, T.; Mori, T.; Nakao, A.; Murakami, Y.; Schlueter, J. A. (Materials Science Division); (Tokyo Inst. Tech.); (High Energy Accl. Res. Org.)

2012-01-01

299

Efficient degradation of TCE in groundwater using Pd and electro-generated H2 and O2: a shift in pathway from hydrodechlorination to oxidation in the presence of ferrous ions.  

PubMed

Degradation of trichloroethylene (TCE) in simulated groundwater by Pd and electro-generated H(2) and O(2) is investigated in the absence and presence of Fe(II). In the absence of Fe(II), hydrodechlorination dominates TCE degradation, with accumulation of H(2)O(2) up to 17 mg/L. Under weak acidity, low concentrations of oxidizing •OH radicals are detected due to decomposition of H(2)O(2), slightly contributing to TCE degradation via oxidation. In the presence of Fe(II), the degradation efficiency of TCE at 396 ?M improves to 94.9% within 80 min. The product distribution proves that the degradation pathway shifts from 79% hydrodechlorination in the absence of Fe(II) to 84% •OH oxidation in the presence of Fe(II). TCE degradation follows zeroth-order kinetics with rate constants increasing from 2.0 to 4.6 ?M/min with increasing initial Fe(II) concentration from 0 to 27.3 mg/L at pH 4. A good correlation between TCE degradation rate constants and •OH generation rate constants confirms that •OH is the predominant reactive species for TCE oxidation. Presence of 10 mM Na(2)SO(4), NaCl, NaNO(3), NaHCO(3), K(2)SO(4), CaSO(4), and MgSO(4) does not significantly influence degradation, but sulfite and sulfide greatly enhance and slightly suppress degradation, respectively. A novel Pd-based electrochemical process is proposed for groundwater remediation. PMID:22315993

Yuan, Songhu; Mao, Xuhui; Alshawabkeh, Akram N

2012-03-01

300

Efficient Degradation of TCE in Groundwater Using Pd and Electro-generated H2 and O2: A Shift in Pathway from Hydrodechlorination to Oxidation in the Presence of Ferrous Ions  

PubMed Central

Degradation of trichloroethylene (TCE) in simulated groundwater by Pd and electro-generated H2 and O2 is investigated in the absence and presence of Fe(II). In the absence of Fe(II), hydrodechlorination dominates TCE degradation, with accumulation of H2O2 up to 17 mg/L. Under weak acidity, low concentrations of oxidizing •OH radical are detected due to decomposition of H2O2, slightly contributing to TCE degradation via oxidation. In the presence of Fe(II), the degradation efficiency of TCE at 396 ?M improves to 94.9% within 80 min. The product distribution proves that the degradation pathway shifts from 79% hydrodechlorination in the absence of Fe(II) to 84% •OH oxidation in the presence of Fe(II). TCE degradation follows zeroth-order kinetics with rate constants increasing from 2.0 to 4.6 ?M/min with increasing initial Fe(II) concentration from 0 to 27.3 mg/L at pH 4. A good correlation between TCE degradation rate constants and •OH generation rate constants confirms that •OH is the predominant reactive species for TCE oxidation. Presence of 10 mM Na2SO4, NaCl, NaNO3, NaHCO3, K2SO4, CaSO4 and MgSO4 does not significantly influence degradation, but sulfite and sulfide greatly enhance and slightly suppresses degradation, respectively. A novel Pd-based electrochemical process is proposed for groundwater remediation.

Yuan, Songhu; Mao, Xuhui; Alshawabkeh, Akram N.

2012-01-01

301

Kinetics of the transformation of trichloroethylene and tetrachloroethylene by iron sulfide  

SciTech Connect

The transformation of trichloroethylene (TCE), tetrachloroethylene (PCE), and 1,1-dichloroethylene FeS in aqueous solution at pH 8.3 was studied in batch experiments. TCE and PCE were transformed by FeS with pseudo-first-order rate constants, corrected for partitioning to the sample headspace, of (1.49 [+-] 0.14) [times] 10[sup [minus]3] h[sup [minus]1] (TCE) and (5.7 [+-] 1.0) [times] 10[sup [minus]4] h[sup [minus]1] (PCE). A 17% decrease in the concentration of 1,3-DCE was observed over 120 days; however, no reaction products were detected. TCE and PCE transformation data were fit to a rate law assuming transformation of TCE via parallel reaction pathways to acetylene and cis-1,2-dichloroethylene (cis-DCE) and transformation of PCE via parallel reaction pathways to acetylene and TCE. Acetylene was the major reaction product for both TCE and PCE. Determination of rate constants for each reaction pathway indicated that TCE was transformed to acetylene 11.8 [+-] 1.1 times faster than to cis-DCE and that PCE was transformed to acetylene 8.2 [+-] 1.8 times faster than to TCE. Additional minor reaction products were vinyl chloride (VC) for TCE and cis-DCE for PCE. Detection of acetylene as the major product of both TCE and PCE transformation by FeS contrasts with the sequential hydrogenolysis products typically observed in the microbial transformation of these compounds, making acetylene a potential indicator of abiotic transformation of TCE and PCE by FeS in natural systems.

Butler, E.C.; Hayes, K.F. (Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Civil and Environmental Engineering)

1999-06-15

302

Evaluating chlorine isotope effects from isotope ratios and mass spectra of polychlorinated molecules.  

PubMed

Compound-specific chlorine isotope analysis receives much interest to assess the fate of chlorinated hydrocarbons in contaminated environments. This paper provides a theoretical basis to calculate isotope ratios and quantify isotope fractionation from ion-current ratios of molecular- and fragment-ion multiplets. Because both (35)Cl and (37)Cl are of high abundance, polychlorinated hydrocarbons consist of molecules containing different numbers of (37)Cl denoted as isotopologues. We show that, during reactions, the changes in isotopologue ratios are proportional to changes in the isotope ratio assuming a nonselective isotope distribution in the initial compound. This proportionality extents even to fragments formed in the ion source of a mass spectrometer such as C 2Cl 2 (double dechlorinated fragment of perchloroethylene, PCE). Fractionation factors and kinetic isotope effects (KIE) may, therefore, be evaluated from isotope, isotopologue or even fragment ratios according to conventional simple equations. The proportionality is exact with symmetric molecules such as dichloroethylene (DCE) and PCE, whereas it is approximately true with molecules containing nonreactive positions such as trichloroethylene (TCE). If in the latter case isotope ratios are derived from dechlorinated fragments, e.g., C 2HCl 2, it is important that fragmentation in the ion source affect all molecular positions alike, as otherwise isotopic changes in reactive positions may be underrepresented. PMID:18484745

Elsner, Martin; Hunkeler, Daniel

2008-05-17

303

1992 toxic hazards research unit annual report. Annual report, 1 October 1991-30 September 1992  

SciTech Connect

This report presents a review of the activities of the Toxic Hazards Research Unit (THRU) for the period 1 October 1991 through 30 September 1992. The THRU conducts descriptive, mechanistic, and predictive toxicology research and toxicological risk assessments to provide data to predict health hazards and to assess health risks associated with human exposure to chemicals and materials associated with military systems and operational environments. The report includes summaries of ongoing or completed research activities for the individual toxicology research requirements of the U.S. Air Force, Army, and Navy; highlights of the research support elements and conference activities of the THRU; and appendices that describe the THRU organization and its publications and presentations. 1,3,3-Trinitroazetidine (TNAZ), 1,3,5-Trinitrobenzene (TNB), Carboxylic acid metabolite, Chlorofluorocarbon, Chloroform, Delayed neurotoxicity, Halon replacement, Hydraulic fluid, Hydrazine, Inhalation, Jet engine oil, Lactational transfer, Methylene chloride, MIL-H-19457C, Neurotoxic Esterase (NTE), OTTO Fuel II, Perchloroethylene (PCE), Physiologically Based Pharmacokinetic (PBPK) modeling, Polychlorotrifluoroethylene (pCTFE), Quantitative Structure-Activity Relationships (QSAR), Reproductive, Risk assessment, Smoke, Tetrachloroethylene (PCE), Toxic dust, Vinyl Chloride (VC) and Trichloroethylene (TCE) mixture.

Wall, H.G.; Dodd, D.E.; Vinegar, A.; Schneider, M.G.

1993-04-01

304

Boosting sensitivity of organic vapor detection with silicone block polyimide polymers.  

PubMed

We demonstrate that silicone block polyimide polymers have an unusually high sensitivity to nonpolar organic vapors, including chlorinated organic solvent vapors. When 0.18-5.34-microm-thick films of silicone block polyimide polymers were deposited onto 10-MHz thickness shear mode (TSM) oscillators, these films were implemented to detect parts-per-billion concentrations of trichloroethylene (TCE) with a detection sensitivity of 0.5-23.5 Hz per 500 ppb of vapor. With a film thickness of 3.4 microm (91.5-kHz frequency shift upon film deposition), optimized for the minimal sensor noise of 0.04 Hz, the calculated detection limit of sensor response (S/N = 3) was 3 ppb of TCE. Detection limits for other chlorinated organic solvent vapors, such as perchloroethylene (PCE), cis-1,2-dichloroethylene (DCE), trans-1,2-DCE, 1,1-DCE, and vinyl chloride (VC) were 0.6, 6, 6, 11, and 13 ppb, respectively. Assuming only the mass-loading response when deposited onto the TSM devices, silicone block polyimide polymers have partition coefficients of over 200 000 to parts-per-billion concentrations of TCE that make them at least 100 times more sensitive than other known polymers for TCE detection. We observed that unlike conventional polyimides, water sensitivity of the new hybrid polyimides is suppressed because of the silicone soft block. Water sensitivity is comparable with the sensor response to nonpolar organic vapors. The high sensitivity and long-term stability of these sensor materials make them attractive for ultrasensitive practical sensors. PMID:15571355

Potyrailo, Radislav A; Sivavec, Timothy M

2004-12-01

305

PCE: Piecewise Convex Endmember Detection  

Microsoft Academic Search

A new hyperspectral endmember detection method that represents endmembers as distributions, autonomously partitions the input data set into several convex regions, and simultaneously determines endmember distributions (EDs) and proportion values for each convex region is presented. Spectral unmixing methods that treat endmembers as distributions or hyperspectral images as piecewise convex data sets have not been previously developed. Piecewise convex endmember

Alina Zare; Paul Gader

2010-01-01

306

Airlift recirculation well test results -- Southern sector  

SciTech Connect

Chlorinated solvents used in the A and M-Areas at the Savannah River Site (SRS) from 1952--1982 have contaminated the groundwater under the site. A plume of groundwater contaminated with trichloroethylene (TCE) and perchloroethylene (PCE) in the Lost Lake aquifer is moving generally southward with the natural flow of groundwater. To comply with the requirements of the current SCDHEC Part B Permit, a series of wells is being installed to contain and treat the plume. Airlift Recirculation Wells (ARW) are a new and innovative technology with potential for more cost effective implementation than conventional pump and treat systems. Two Airlift Recirculation Wells have been installed and tested to quantify performance parameters needed to locate a line of these wells along the leading edge of the contaminant plume. The wells proved to be very sensitive to proper development, but after this requirement was met, performance was very good. The Zone of Capture has been estimated to be within a radius of 130--160 ft. around the wells. Thus a line of wells spaced at 250 ft. intervals could intercept the contaminant plume. At SSR-012, TCE was stripped from the groundwater at approximately 1.2 lb./day. The longer term effect of the recirculation wells upon the plume and the degree of recirculation within the aquifer itself will require additional data over a longer time period for an accurate review. Data collection is ongoing.

White, R.M.; Hiergesell, R.A.

1997-08-01

307

Characterization of Hydrogenase and Reductive Dehalogenase Activities of Dehalococcoides ethenogenes Strain 195  

Microsoft Academic Search

Dehalococcoides ethenogenes strain 195 reductively dechlorinates tetrachloroethene (PCE) and trichlo- roethene (TCE) to vinyl chloride and ethene using H2 as an electron donor. PCE- and TCE-reductive dehalogenase (RD) activities were mainly membrane associated, whereas only about 20% of the hydrogenase activity was membrane associated. Experiments with methyl viologen (MV) were consistent with a periplasmic location for the RDs or a

Ivonne Nijenhuis; Stephen H. Zinder

2005-01-01

308

Relationship between geochemical parameters and the occurrence of Dehalococcoides DNA in contaminated aquifers  

Microsoft Academic Search

Strains of Dehalococcoides are the only microbes known that can completely dechlorinate PCE, TCE, cis-DCE, and vinyl chloride to ethylene. Either naturally occurring strains or bioaugmentation cultures of Dehalococcoides are widely used for in situ bioremediation of contaminated groundwater. Naturally occurring strains have an important role in natural attenuation of PCE, TCE, cis-DCE, and vinyl chloride in groundwater. This study

Xiaoxia Lu; John T. Wilson; Donald H. Kampbell

2006-01-01

309

Competitive Sorption and Desorption of Chlorinated Organic Solvents (DNAPLs) in Engineered Natural Organic Matter  

SciTech Connect

The effects of artificially accelerated geochemical condensation and maturation of natural organic matter on the sorption and desorption of trichloroethylene (TCE) and tetrachloroethylene (PCE) were studied. The sorption and desorption of TCE in the presence and absence of the competing PCE and 1,2-dichlorobenzene (DCB) were also examined. A sphagnum peat comprising geologically young organic matter was artificially ''aged'' using superheated water, thus increasing the aromaticity and the degree of condensation of its associated organic matter. The sorption of all solutes tested were increased remarkably and their respective desorptions reduced, by the aged peat. The sorption capacities and isotherm nonlinearities of the peat for both TCE and PCE were found to increase as treatment temperature increased. In the competitive sorption studies, both PCE and DCB were found to depress TCE sorption, with PCE having greater effects than DCB, presumably because the molecular structure o f the former is more similar to that of TCE.

Tang, Jixin; Weber, Walter J., Jr.

2004-03-31

310

Degradation of Organochlorine Compounds Using Zero Valent Iron (ZVI) Nano Particles Impregnated in Hydrophobic Modified Bentonite  

Microsoft Academic Search

\\u000a The degradation of perchloroethylene (PCE) adsorbed on hydrophobic modified bentonite was investigated. The degradation occurred\\u000a via reduction of iron particles with zero valence (ZVI) incorporated in hydrophobic surface of bentonite. We compared two\\u000a different systems, one containing ZVI and another without ZVI. The degradation of PCE was accompanied by decreasing concentrations\\u000a of PCE and the increase of resulting compounds such

Sandro Froehner; M. Maceno; E. C. Luz; K. S. Machado; F. Falcão

311

CROWTM PROCESS APPLICATION FOR SITES CONTAMINATED WITH LIGHT NON-AQUEOUS PHASE LIQUIDS AND CHLORINATED HYDROCARBONS  

SciTech Connect

Western Research Institute (WRI) has successfully applied the CROWTM (Contained Recovery of Oily Wastes) process at two former manufactured gas plants (MGPs), and a large wood treatment site. The three CROW process applications have all occurred at sites contaminated with coal tars or fuel oil and pentachlorophenol (PCP) mixtures, which are generally denser than water and are classified as dense non-aqueous phase liquids (DNAPLs). While these types of sites are abundant, there are also many sites contaminated with gasoline, diesel fuel, or fuel oil, which are lighter than water and lie on top of an aquifer. A third site type occurs where chlorinated hydrocarbons have contaminated the aquifer. Unlike the DNAPLs found at MGP and wood treatment sites, chlorinated hydrocarbons are approximately one and a half times more dense than water and have fairly low viscosities. These contaminants tend to accumulate very rapidly at the bottom of an aquifer. Trichloroethylene (TCE) and perchloroethylene, or tetrachloroethylene (PCE), are the major industrial chlorinated solvents that have been found contaminating soils and aquifers. The objective of this program was to demonstrate the effectiveness of applying the CROW process to sites contaminated with light non-aqueous phase liquids (LNAPLs) and chlorinated hydrocarbons. Individual objectives were to determine a range of operating conditions necessary to optimize LNAPL and chlorinated hydrocarbon recovery, to conduct numerical simulations to match the laboratory experiments and determine field-scale recoveries, and determine if chemical addition will increase the process efficiency for LNAPLs. The testing consisted of twelve TCE tests; eight tests with PCE, diesel, and wood treatment waste; and four tests with a fuel oil-diesel blend. Testing was conducted with both vertical and horizontal orientations and with ambient to 211 F (99 C) water or steam. Residual saturations for the horizontal tests ranged from 23.6% PV to 0.3% PV. Also conducted was screening of 13 chemicals to determine their relative effectiveness and the selection of three chemicals for further testing.

L.A. Johnson, Jr.

2003-06-30

312

Assessing interaction thresholds for trichloroethylene in combination with tetrachloroethylene and 1,1,1-trichloroethane using gas uptake studies and PBPK modeling  

Microsoft Academic Search

The volatile organic solvents trichloroethylene (TCE), tetrachloroethylene (perchloroethylene, PERC), and 1,1,1-trichloroethane (methylchloroform, MC) are widely distributed environmental pollutants and common contaminants of many chemical waste sites. To investigate the mode of pharmacokinetic interactions among TCE, PERC, and MC and to calculate defined \\

Ivan D. Dobrev; Melvin E. Andersen; Raymond S. Yang

2001-01-01

313

United States Air Force 611th Civil Engineer Squadron, Elmendorf AFB, Alaska. Final engineering evaluation/cost analysis potential tce impact to the drinking water supply, Galena Airport, Alaska  

SciTech Connect

This decision document presents the selected removal action to address potential trichloroethene (TCE) impact to drinking water supply wells, located in the Installation Restoration Program (IRP) site ST009, otherwise known as the West Unit, at Galena Airport, Alaska. The information fron the RI Report is summarized, along with an analysis of potential removal action alternatives, in the Engineering Evaluation/Cost Analysis (EE/CA).

NONE

1996-02-05

314

Development of an integrated in-situ remediation technology. Topical report for task No. 11 entitled: Evaluation of TCE contamination before and after the field experiment, September 26, 1994--May 25, 1996  

SciTech Connect

Contamination in low permeability soils poses a significant technical challenge to in-situ remediation efforts. Poor accessibility to the contaminants and difficulty in delivery of treatment reagents have rendered existing in-situ treatments such as bioremediation, vapor extraction, pump and treat rather ineffective when applied to low permeability soils present at many contaminated sites. The technology is an integrated in-situ treatment in which established geotechnical methods are used to install degradation zones directly in the contaminated soil and electro-osmosis is utilized to move the contaminants back and forth through those zones until the treatment is completed. The present Topical Report for Task No. 11 summarizes the results of TCE analysis in soil and carbon before and after conducting the field experiment. In addition, a discussion of the TCE material balance demonstrates that the Lasagna{trademark} process is effective in moving TCE from the contaminated soil into carbon treatment zones in the field experiment at DOE`s Gaseous Diffusion Plant in Paducah, Kentucky.

Hughes, B.M.; Athmer, C.J.; Sheridan, P.W. [and others

1997-04-01

315

Desorption Behavior of Trichloroethene and Tetrachloroethene in U.S. Department of Energy Savannah River Site Unconfined Aquifer Sediments  

SciTech Connect

The DOE Savannah River Site (SRS) is evaluating the potential applicability of the monitored natural attenuation (MNA) process as a contributor to the understanding of the restoration of its unconfined groundwater aquifer known to be contaminated with the chlorinated hydrocarbon compounds trichloroethylene (TCE) and tetrachloroethylene (PCE). This report discusses the results from aqueous desorption experiments on SRS aquifer sediments from two different locations at the SRS (A/M Area; P-Area) with the objective of providing technically defensible TCE/PCE distribution coefficient (Kd) data and data on TCE/PCE reversible and irreversible sorption behavior needed for further MNA evaluation.

Riley, Robert G.; Szecsody, Jim E.; Mitroshkov, Alexandre V.; Brown, Christopher F.

2006-06-21

316

Decontamination systems information and research program  

SciTech Connect

It is estimated that over 3700 hazardous waste sites are under the jurisdiction of the Department of Energy (DOE). These sites were primarily generated from 45 years worth of environmental pollution from the design and manufacture of nuclear materials and weapons, and contain numerous types of wastes including: (1) volatile, low-volatile and nonvolatile organics, (2) radionuclides (e.g., uranium, plutonium and cesium), (3) nonradioactive heavy metals (e.g., chromium, nickel, and lead), and (4) toxic chemicals. These contaminants affect several media including soils (saturated and unsaturated), groundwater, vegetation, and air. Numerous and diverse DOE hazardous waste sites can be enumerated from soils contaminated by organics such as trichloroethylene (TCE) and perchloroethylene (PCE) at the Savannah River site to biota and vegetation contaminated by radionuclides such as radiocesium and radiostrontium at the Oak Ridge site. Over the next 30 years, the Department of Energy (DOE) is committed to bringing all its facilities into compliance with applicable Federal, State, and local environmental laws and regulations. This clean-up task is quite complex involving numerous sites containing various radioactive, organic and inorganic contaminants. To perform this clean-up effort in the most efficient manner at each site will require that DOE managers have access to all available information on pertinent technologies; i.e., to aid in maximum technology transfer. The purpose of this effort is to systematically develop a databast of those currently available and emerging clean-up technologies.

Not Available

1993-01-01

317

Decontamination systems information and research program. Quarterly technical progress report, October 1--December 31, 1992  

SciTech Connect

It is estimated that over 3700 hazardous waste sites are under the jurisdiction of the Department of Energy (DOE). These sites were primarily generated from 45 years worth of environmental pollution from the design and manufacture of nuclear materials and weapons, and contain numerous types of wastes including: (1) volatile, low-volatile and nonvolatile organics, (2) radionuclides (e.g., uranium, plutonium and cesium), (3) nonradioactive heavy metals (e.g., chromium, nickel, and lead), and (4) toxic chemicals. These contaminants affect several media including soils (saturated and unsaturated), groundwater, vegetation, and air. Numerous and diverse DOE hazardous waste sites can be enumerated from soils contaminated by organics such as trichloroethylene (TCE) and perchloroethylene (PCE) at the Savannah River site to biota and vegetation contaminated by radionuclides such as radiocesium and radiostrontium at the Oak Ridge site. Over the next 30 years, the Department of Energy (DOE) is committed to bringing all its facilities into compliance with applicable Federal, State, and local environmental laws and regulations. This clean-up task is quite complex involving numerous sites containing various radioactive, organic and inorganic contaminants. To perform this clean-up effort in the most efficient manner at each site will require that DOE managers have access to all available information on pertinent technologies; i.e., to aid in maximum technology transfer. The purpose of this effort is to systematically develop a databast of those currently available and emerging clean-up technologies.

Not Available

1993-01-01

318

Halocarbons in the environment: Estimates of thermodynamic properties for aqueous chloroethylene species and their stabilities in natural settings  

NASA Astrophysics Data System (ADS)

Standard partial molal thermodynamic parameters for the aqueous chlorinated-ethylene species, perchloroethylene (PCE), trichloroethylene (TCE), 1,1-dichloroethylene (1,1-DCE), cis-1,2-dichloroethylene ( cis-1,2-DCE), trans-1,2-dichloroethylene ( trans-1,2,-DCE), and vinyl chloride (VC) have been estimated by using experimental gas-solubility data and correlation algorithms. The provided thermodynamic values may be used to calculate properties of reactions involving the aqueous chloroethylene species at a wide range of temperatures and pressures. Estimated values for the chloroethylenes were used, along with published values for minerals, gases, aqueous ions, and aqueous neutral organic species, to calculate the stability of chloroethylene species in equilibrium with the minerals magnetite, hematite, pyrite, and pyrrhotite in the subsurface. Estimated values for the aqueous chloroethylenes were also used to calculate reduction potentials for microbially-mediated reductive dechlorination half-reactions at elevated temperatures. Calculations indicate that all aqueous chloroethylene species are energetically favored to decompose to ethylene(aq) under a wide range of conditions in the subsurface, by both abiotic and biotic pathways. Anaerobic microbially mediated degradation is especially favored under conditions at least sufficiently reducing to promote sulfate-reduction, but not under conditions sufficient for microbial denitrification, pyrolusite reduction, or ferric-iron reduction.

Haas, Johnson R.; Shock, Everett L.

1999-10-01

319

Well Installation Report for Monitoring Wells TCM4, TCM5, and TCM8 and Pilot Hole TGSC-2A  

SciTech Connect

The shallow groundwater and sediments beneath the TNX Area are contaminated with both dissolved and residual chlorinated volatile organic compounds (CVOCs) such as trichloroethylene (TCE), carbon tetrachloride and perchloroethylene (PCE)..The Savannah River Technology Center (SRTC) is studying a new technology for remediating CVOCs known as GeoSiphon. The GeoSiphon Cell is a large diameter well uses granular cast iron for filter pack material and is operated by inducing a siphon to draw contaminated groundwater through the iron filter pack. As groundwater flows through the granular cast iron CVOCs are reduced to ethane, ethene, methane, and chloride ions. Previous laboratory and field studies (ETI, 1996, and Phifer et. al., 1997) conducted by SRTC have shown that granular cast iron is capable of remediating contaminated at TNX. SRTC will be conducting a Dual Cell test of the GeoSiphon technology in 1999 to study the hydraulic interaction of multiple cells operating simultaneously.T his report documents the installation of 3 monitoring wells and 1 pilot hole that were installed to support the Dual phase test. The three monitoring wells will be used to study the hydraulic interaction between the 2 GeoSiphon cells. Continuous core was collected from the proposed location for the second GeoSiphon Cell TGSC-2. Depth discrete samples collected from the core were analyzed for CVOCs.

Nichols, R.L.

1998-10-26

320

Variations of volatile chlorinated hydrocarbons in ambient air at industrial areas in Niigata  

SciTech Connect

Typical volatile chlorinated hydrocarbons (VCHs), 1,1,1-trichloroethane (methyl chloroform, MCF), and trichloroethane (trichloroethylene, TCE) are used as degreasers or cleaners at electrical plants and metalworks; tetrachloroethane (perchloroethylene, PCE) as well as MCF is representative solve-its for dry cleaning. Tetrachloromethane (perchloromethane, PCM) utilized as material for chemicals. Some amounts of VCHs are lost in the process and are introduced to the environment by some routes. In particular, direct exhaust of VCHs into air is one of the most serious routes; 60 to 90 percents of the VCHs used at some metalworks and relative factories were estimated to be emitted into air. Previously reported were the concentration levels of the VCHs in ambient air at some areas the atmospheric VCH concentrations at industrial areas were affected with some factories which used the VCHs, whereas those at a suburban area were lower than those at industrial regions. Furthermore, they were higher in winter season than in summer season, which might be caused by -meteorological factors. In this paper, aerial variations of VCH concentrations during two to five years at three individual industrial areas (i.e., a metalware and houseware manufacturing area, a textile and dyeing industrial area and a chemical engineering area) are presented. 14 refs., 2 figs., 2 tabs.

Kawata, K.; Mukai, H.; Tanabe, H. [Niigata Prefectural Research Lab. for Health and Environment (Japan); Yasuhara, A. [National Inst. for Environmental Studies, Ibaraki (Japan)

1996-07-01

321

Technology status report: Off-gas treatment technologies for chlorinated volatile organic compound air emissions  

SciTech Connect

The purpose of this document is to review technologies for treatment of air streams that contain chlorinated volatile organic compounds (CVOCS) and to describe a Department of Energy Office of Technology Development program that is planned to demonstrate innovative technologies for the abatement of CVOC emissions. This report describes the first phase of testing of off-gas treatment technologies. At least one more phase of testing is planned. Guidance for the preparation of this document was provided by a predecisional draft outline issued by the Department of Energy`s Office of Technology Development. The report is intended to evaluate the technical and regulatory aspects, public acceptance, and estimated costs of technologies selected for development and testing. These technologies are compared to currently practiced or baseline methods for treatment of CVOC-laden airstreams. A brief overview is provided rather than detailed cost and data comparisons because many of these technologies have not yet been field tested. A description of other promising technologies for the treatment of CVOC emissions is also included. Trichloroethylene (TCE) and perchloroethylene (PCE) were used for industrial cleaning and solvent applications for several decades. These chemicals can be classified as CVOCS. As a result of past standard disposal practices, these types of compounds are persistent groundwater and soil contaminants throughout the United States and the Department of Energy Complex.

Rossabi, J.; Haselow, J.S.

1992-04-15

322

Technology status report: Off-gas treatment technologies for chlorinated volatile organic compound air emissions  

SciTech Connect

The purpose of this document is to review technologies for treatment of air streams that contain chlorinated volatile organic compounds (CVOCS) and to describe a Department of Energy Office of Technology Development program that is planned to demonstrate innovative technologies for the abatement of CVOC emissions. This report describes the first phase of testing of off-gas treatment technologies. At least one more phase of testing is planned. Guidance for the preparation of this document was provided by a predecisional draft outline issued by the Department of Energy's Office of Technology Development. The report is intended to evaluate the technical and regulatory aspects, public acceptance, and estimated costs of technologies selected for development and testing. These technologies are compared to currently practiced or baseline methods for treatment of CVOC-laden airstreams. A brief overview is provided rather than detailed cost and data comparisons because many of these technologies have not yet been field tested. A description of other promising technologies for the treatment of CVOC emissions is also included. Trichloroethylene (TCE) and perchloroethylene (PCE) were used for industrial cleaning and solvent applications for several decades. These chemicals can be classified as CVOCS. As a result of past standard disposal practices, these types of compounds are persistent groundwater and soil contaminants throughout the United States and the Department of Energy Complex.

Rossabi, J.; Haselow, J.S.

1992-04-15

323

The state of permanganate with relation to in situ chemical oxidation  

SciTech Connect

In Situ Chemical Oxidation (ISCO) with permanganate had its beginnings over 10 years ago. Since that time, many sites have been successfully treated for organic compounds including chlorinated ethenes (perchloroethylene, trichloroethylene, etc.) phenols, explosives such as RDX, and many other organics. The successful application of ISCO with permanganate requires the integration of many site-specific factors into the remedial design. ISCO with permanganate is an effective technology, not only for its oxidative properties and persistence, but also for its application flexibility to remediate soil and groundwater. The merits of any type of treatment technology can be assessed in terms of effectiveness, ease of use, reaction rate, and cost. The use of permanganate for in situ chemical oxidation results in the complete mineralization of TCE and PCE and can result in treatment levels below detection limits. Permanganate is a single component oxidizer, which is easily handled, mixed and distributed to the subsurface. Permanganate is also inexpensive to design and implement as compared to other technologies. This presentation will provide a general overview of the application and safety aspects of ISCO with permanganate. This paper will discuss the advantages and limitations of this technology, typical cost ranges, site evaluation and application technologies. (authors)

Veronda, Brenda; Dingens, Matthew [Carus Corporation, 315 5th Street, Peru, IL 61354 (United States)

2007-07-01

324

Fiber optic spectrochemical emission sensor: Detection of volatile chlorinated compounds in air and water using ultra-thin membranes  

SciTech Connect

Prior work on the fiber optic spectrochemical emission sensor called HaloSnif{trademark} has been extended to include an ultra-thin membrane which allows passage of volatile organic chlorinated compounds (VOCl). The membrane has been demonstrated to exclude H{sub 2}O during VOCl monitoring. The system is capable of measuring VOCl in gas-phase samples or aqueous solutions over a wide linear dynamic range. The lower limit of detection for trichloroethylene (TCE), perchloroethylene (PCE), carbon tetrachloride (CCl{sub 4}), and other related compounds in the gas-phase is 1 to 5 ppm{sub v/v}, and in the aqueous-phase is 5 to 10 mg/L. Waste site characterization and remediation activities often require chemical analysis in the vadose zone and in groundwater. These analyses are typically performed in analytical laboratories using widely accepted standardized methods such as gas chromatography, gas chromatography/mass spectrometry. The new developments with HaloSnif provide rapid field screening which can augment the standardized methods.

Anheier, N.C. Jr.; Olsen, K.B.; Osantowski, R.E.; Evans, J.C. Jr.; Griffin, J.W.

1993-05-01

325

Vibrational Spectroscopic and X-Ray Diffraction Studies of Cerium Zirconium Oxides with Ce\\/Zr Composition Ratio=1 Prepared by Reduction and Successive Oxidation of t?-(Ce 0.5Zr 0.5)O 2 Phase  

Microsoft Academic Search

Cerium zirconium oxides with the composition CeZrO4 were prepared by oxidizing in O2 at 873 K precursors with the composition CeZrO3.5+? (?<0.3). The precursors were prepared by reducing the t?-(Ce0.5Zr0.5)O2 phase at 873?Tred.?1573 K. The CeZrO4 compounds together with the precursors were characterized by powder X-ray diffraction and IR and Raman spectroscopies. In the case of 1323?Tred.?1573 K, the precursors

Takahisa Omata; Haruo Kishimoto; Shinya Otsuka-Yao-Matsuo; Norikazu Ohtori; Norimasa Umesaki

1999-01-01

326

Contributions of Fe Minerals to Abiotic Dechlorination  

EPA Science Inventory

Most applications of enhanced in situ bioremediation are based on biological reductive dechlorination. Anaerobic metabolism can also produce reactive minerals that allow for in situ biogeochemical transformation of chlorinated organic contaminants such as PCE, TCE, and cis-DCE. ...

327

DEMONSTRATION BULLETIN: AQUADETOX®/ SVE SYSTEM and AWD Technologies, Inc.  

EPA Science Inventory

The AWD technology simultaneously treats groundwater and soil-gas contaminated with volatile or ganic compounds (VOC), such as trichloroethylene (TCE) and tetrachloroethylene (PCE). This technology integrates two processes: (1) AquaDetox®, a moderate vacuum (pressure about 50 ...

328

IN-PLACE REGENERATION OF SVE LOADED GAC USING FENTON'S REAGENTS  

EPA Science Inventory

Ten out of the 25 most frequently detected groundwater contaminants at hazardous waste sites are chlorinated volatile organic compounds (VOCs) 1. Trichloroethylene (TCE) and tetrachloroethylene (PCE) are among the top three 1. Granular activated carbon (GAC) adsorption is widel...

329

IN-PLACE REGENERATION OF SVE LOADED GAC USING FENTON'S REAGENTS  

EPA Science Inventory

Ten out of the 25 most frequently detected groundwater contaminants at hazardous waste sites are chlorinated volatile organic compounds (VOCs) 1 . Trichloroethylene (TCE) and tetrachloroethylene (PCE) are among the top three 1 . Granular activated carbon (GAC) adsorption is w...

330

RELATIONSHIP BETWEEN GEOCHEMICAL PARAMETERS AND THE OCCURRENCE OF DEHALOCOCCOIDES DNA IN CONTAMINATED AQUIFERS  

EPA Science Inventory

Stains of Dehalococcoides are the only microbes known that can completely dechlorinate PCE, TCE, cis-DCE and vinyl chloride to ethylene. Either naturally-occurring strains or bioaugmentation cultures of Dehalococcoides are widely used for in situ bioremediation ...

331

DETERMINATION OF CHLOROETHENES IN ENVIRONMENTAL BIOLOGICAL SAMPLES USING GAS CHROMATOGRAPHY COUPLED WITH SOLID PHASE MICRO EXTRACTION  

EPA Science Inventory

An analytical method has been developed to determine the chloroethene series, tetrachloroethene (PCE), trichloroethene (TCE),cisdichloroethene (cis-DCE) andtransdichloroethene (trans-DCE) in environmental biotreatment studies using gas chromatography coupled with a solid phase mi...

332

Innovative Technology Summary Report: Remediation of DNAPLs in Low Permeability Soils. Subsurface Contaminants Focus Area.  

National Technical Information Service (NTIS)

Dense, non-aqueous phase liquid (DNAPL) compounds like trichloroethene (TCE) and perchloroethene (PCE) are prevalent at U. S. Department of Energy (DOE), other government, and industrial sites. Their widespread presence in low permeability media (LPM) pos...

2000-01-01

333

Development of Radon as a Natural Tracer for Monitoring the Remediation of NAPL Contamination in the Subsurface. Annual Report 2002.  

National Technical Information Service (NTIS)

Dense non-aqueous phase liquids (DNAPLs) such as trichloroethene (TCE) and perchloroethene (PCE) present long-term challenges in terms of quantification in the subsurface at many DOE facilities. Over the past year we have continued investigating a potenti...

B. M. Davis L. Semprini J. Istok

2002-01-01

334

MICROBIAL UTILIZATION OF VADOSE ZONE ORGANIC CARBON FOR REDUCTIVE DECHLORINATION OF TETRACHLOROETHENE  

EPA Science Inventory

Aqueous extracts from a calcareous spodosol were used as the primary substrate to study the reductive dechlorination of tetrachloroethene (PCE). A comparison was made between extracts obtained using pure water and water saturated with trichloroethene (TCE). The latter solutions w...

335

Controlled release, blind test of DNAPL remediation by ethanol flushing  

Microsoft Academic Search

A dense nonaqueous phase liquid (DNAPL) source zone was established within a sheet-pile isolated cell through a controlled release of perchloroethylene (PCE) to evaluate DNAPL remediation by in-situ cosolvent flushing. Ethanol was used as the cosolvent, and the main remedial mechanism was enhanced dissolution based on the phase behavior of the water–ethanol–PCE system. Based on the knowledge of the actual

Michael C. Brooks; Michael D. Annable; P. Suresh C. Rao; Kirk Hatfield; James W. Jawitz; William R. Wise; A. Lynn Wood; Carl G. Enfield

2004-01-01

336

Green remediation: enhanced reductive dechlorination using recycled rinse water as bioremediation substrate  

SciTech Connect

Enhanced reductive dechlorination (ERD) has rapidly become a remedy of choice for use on chlorinated solvent contamination when site conditions allow. With this approach, solutions of an organic substrate are injected into the affected aquifer to stimulate biological growth and the resultant production of reducing conditions in the target zone. Under the reducing conditions, hydrogen is produced and ultimately replaces chlorine atoms on the contaminant molecule causing sequential dechlorination. Under suitable conditions the process continues until the parent hydrocarbon precursor is produced, such as the complete dechlorination of trichloroethylene (TCE) to ethene. The process is optimized by use of a substrate that maximizes hydrogen production per unit cost. When natural biota are not present to promote the desired degradation, inoculates can be added with the substrate. The in-situ method both reduces cost and accelerates cleanup. Successful applications have been extended from the most common chlorinated compounds perchloroethylene (PCE) and TCE and related products of degradation, to perchlorate, and even explosives such as RDX and trinitrotoluene on which nitrates are attacked in lieu of chloride. In recent work, the process has been further improved through use of beverage industry wastewaters that are available at little or no cost. With material cost removed from the equation, applications can maximize the substrate loading without significantly increasing total cost. The extra substrate loading both accelerates reaction rates and extends the period of time over which reducing conditions are maintained. In some cases, the presence of other organic matter in addition to simple sugars provides for longer performance times of individual injections, thereby working in a fashion similar to emulsified vegetable oil. The paper discusses results of applications at three different sites contaminated with chlorinated ethylenes. The applications have included wastewaters of both natural fruit juices and corn syrup solutions from carbonated beverages. Cost implications include both the reduced cost of substrate and the cost avoidance of needing to pay for treatment of the wastewater. (authors)

Dawson, Gaynor; McKeon, Tom [CALIBRE Systems, Inc., Bellevue, WA (United States)

2007-07-01

337

Innovative Technologies And Vadose Zone Treatment Of Chlorinated Volatile Organic Compounds - Case Study  

SciTech Connect

Over the last 10 years a mix of innovative and conventional characterization techniques has been used to assess the contamination of vadose zone sediments beneath the pilot-scale test facility known as TNX at the Savannah River Site (SRS) in South Carolina. Shallow soils and groundwater beneath the TNX facility are contaminated with chlorinated volatile organic compounds (CVOCs), trichloroethylene (TCE), carbon tetrachloride (CCl{sub 4}), perchloroethylene (PCE), and chloroform (CHCl{sub 3}). An interim pump and treat remediation system was placed in operation in 1996 to provide hydraulic containment of groundwater containing greater than 500 ug/L dissolved TCE. In 1994, a vadose zone study was initiated to determine the degree and extent of CVOC contamination above the contaminated groundwater. Headspace sampling and analysis, acoustic infrared spectroscopy, cone penetrometry, and vadose zone pumping tests were used to determine contaminant concentrations and physical properties related to soil vapor extraction. In 2001, soil vapor extraction (SVE), a presumptive remedy for CVOCs in soils similar to those present beneath TNX, was selected to treat the CVOC contamination. Cone Penetrometer Testing (CPT) with soil vapor sampling provided a detailed understanding of the subsurface geology and CVOC distribution which was essential for proper well design and placement. Twelve SVE wells were installed using direct push technology (DPT) and were tested to determine specific capacity and CVOC concentrations. This information was then used to develop a strategy for operating the SVE system. Based on the results of the baseline testing and previous studies, sets of 2 to 3 extraction wells will be treated using SVE at one month intervals. This will allow continuous operation of the SVE system and give individual wells up to 3 months for rebound between treatments. This method of operation is intended to maximize contaminant recovery from individual wells and reduce the overall capital investment and operating cost of the SVE system.

NOONKESTER, JAY V.; NICHOLS, RALPH L.; DIXON, KENETH L.

2005-08-02

338

Investigating the role of atomic hydrogen on chloroethene reactions with iron using tafel analysis and electrochemical impedance spectroscopy.  

PubMed

Metallic iron filings are commonly employed as reducing agents in permeable barriers used for remediating groundwater contaminated by chlorinated solvents. Reactions of trichloroethylene (TCE) and tetrachloroethylene (PCE) with zerovalent iron were investigated to determine the role of atomic hydrogen in their reductive dechlorination. Experiments simultaneously measuring dechlorination and iron corrosion rates were performed to determine the fractions of the total current going toward dechlorination and hydrogen evolution. Corrosion rates were determined using Tafel analysis, and dechlorination rates were determined from rates of byproduct generation. Electrochemical impedance spectroscopy (EIS) was used to determine the number of reactions that controlled the observed rates of chlorocarbon disappearance, as well as the role of atomic hydrogen in TCE and PCE reduction. Comparison of iron corrosion rates with those for TCE reaction showed that TCE reduction occurred almost exclusively via atomic hydrogen at low pH values and via atomic hydrogen and direct electron transfer at neutral pH values. In contrast, reduction of PCE occurred primarily via direct electron transfer at both low and neutral pH values. At low pH values and micromolar concentrations, TCE reaction rates were faster than those for PCE due to more rapid reduction of TCE by atomic hydrogen. At neutral pH values and millimolar concentrations, PCE reaction rates were faster than those for TCE. This shift in relative reaction rates was attributed to a decreasing contribution of the atomic hydrogen reaction mechanism with increasing halocarbon concentrations and pH values. The EIS data showed that all the rate limitations for TCE and PCE dechlorination occurred during the transfer of the first two electrons. Results from this study show that differences in relative reaction rates of TCE and PCE with iron are dependent on the significance of the reduction pathway involving atomic hydrogen. PMID:12967110

Wang, Jiankang; Farrell, James

2003-09-01

339

Anaerobic biotransformation of trichlorofluoroethene in groundwater microcosms  

SciTech Connect

The biological reduction of trichlorofluoroethene (TCFE) was investigated in anaerobic groundwater microcosms. TCFE was reductively dehalogenated by microorganisms to produce three dichlorofluoroethene isomers, with cis-1,2-dichlorofluoroethene (c-DCFE) being the main isomer formed. Further sequential biological transformation of these compounds to mono-chlorofluoroethene isomers was incomplete and occurred at much slower rates. The rates of TCFE reduction were compared to the rates of reduction of two common chlorinated solvents, perchloroethene (PCE) and trichloroethene (TCE), when present at similar concentrations. Aqueous concentrations ranged from 7.0 to 14.0 mg/L for TCFE and from 7.5 to 15.0 mg/L for PCE and TCE. Similar rates of PCE and TCE transformation relative to TCFE were observed in single-compound tests (PCE, TCE, and TCFE in separate microcosms) and when the contaminants were present together as mixtures in the microcosms. The close similarities between the time course and kinetics of TCFE degradation and the degradation of both PCE and TCE, when present at comparable initial concentrations, suggest that TCFE could potentially be used as a benign reactive tracer to measure in-situ rates of PCE and TCE transformation in contaminated environments.

Vancheeswaran, S.; Semprini, L. (Oregon State Univ., Corvallis, OR (United States). Dept. of Civil, Construction, and Environmental Engineering); Hyman, M.R. (North Carolina State Univ., Raleigh, NC (United States). Dept. of Microbiology)

1999-06-15

340

Effects of chlorinated solvents on four species of North American amphibians.  

PubMed

Tetrachloroethylene (PCE), a dry cleaning and degreasing solvent, can enter groundwater through accidental leaks or spills, and concentrations as high as 75 mg/L have been reported in Canadian aquifers. Amphibians in wetlands receiving contaminated groundwater may be exposed to PCE and its degradation products, but little information is available on the impacts of these compounds on indigenous amphibian species. Acute (96-h static renewal) exposures to PCE and its major degradation products, trichloroethylene (TCE) and cisand trans-dichloroethylene, were conducted on embryos of four North American amphibian species: wood frogs (Rana sylvatica), green frogs (R. clamitans), American toads (Bufo americanus), and spotted salamanders (Ambystoma maculatum). Subsequently, chronic exposures to PCE and TCE were conducted with the larvae of American toads. Both PCE and TCE were teratogenic to amphibian embryos; median effective concentrations (EC50s) for developmental deformities produced by PCE and TCE exposure for wood frogs and green frogs were 12 and 40 mg/L, respectively. Embryonic survivorship, however, was not compromised at these concentrations. American toads were less sensitive; the EC50 for developmental abnormalities was not attained at the highest test concentrations, 45 and 85 mg/L PCE and TCE, respectively. These results are pertinent in assessing the impact of groundwater pollution on an aquifer-fed wetland. PMID:15346783

McDaniel, T V; Martin, P A; Ross, N; Brown, S; Lesage, S; Pauli, B D

2004-07-01

341

PCE4: Models of Organisational Failures.  

National Technical Information Service (NTIS)

The purpose of this deliverable is to provide a taxonomy of organizational failures, so that there is a basis for analyzing some of the possible organizational failure modes resulting from putting together two or more organizational systems, each with its...

J. E. Dobson P. Periorellisvan

2002-01-01

342

Chlorination byproducts induce gender specific autistic-like behaviors in CD1 mice  

Microsoft Academic Search

In 2000, the Agency for Toxic Substances and Disease Registry (ATSDR) released a report concerning elevated autism prevalence and the presence water chlorination byproducts in the municipal drinking water supply in Brick Township, New Jersey. The ATSDR concluded that it was unlikely that these chemicals, specifically chloroform, bromoform (Trihalomethanes; THMs) and tetrachloroethylene (Perchloroethylene; PCE) had contributed to the prevalence of

Sara Rose Guariglia; Edmund C. Jenkins; Kathryn K. Chadman; Guang Y. Wen

343

Degradation of Environmental Contaminants with Water-Soluble Cobalt Catalysts: An Integrative Inorganic Chemistry Investigation  

ERIC Educational Resources Information Center

|We present an integrative laboratory investigation incorporating skills from inorganic chemistry, analytical instrumentation, and physical chemistry applied to a laboratory-scale model of the environmental problem of chlorinated ethylenes in groundwater. Perchloroethylene (C[subscript 2]Cl[subscript 4], PCE) a common dry cleaning solvent,…

Evans, Alexandra L.; Messersmith, Reid E.; Green, David B.; Fritsch, Joseph M.

2011-01-01

344

Controlled release, blind tests of DNAPL characterization using partitioning tracers  

Microsoft Academic Search

The partitioning tracer technique for dense nonaqueous phase liquid (DNAPL) characterization was evaluated in an isolated test cell, in which controlled releases of perchloroethylene (PCE) had occurred. Four partitioning tracer tests were conducted, two using an inverted, double five-spot pumping pattern, and two using vertical circulation wells. Two of the four tests were conducted prior to remedial activities, and two

Michael C Brooks; Michael D Annable; P. Suresh C Rao; Kirk Hatfield; James W Jawitz; William R Wise; A. Lynn Wood; Carl G Enfield

2002-01-01

345

Methods for environmental monitoring of DOE waste disposal and storage sites. Semiannual progress report, April 1, 1988--September 30, 1988  

SciTech Connect

Perchloroethylene (PCE) is a persistent environmental contaminant whose chemical stability and hydrophobicity have made it difficult to remove from contaminated groundwater. PCE is also toxic and has been implicated as a carcinogen. This study was aimed at assessing methods for biological degradation of PCE. As a part of the study, the authors have characterized possible products of the degradation of PCE, and have determined the effects of detergents and solvents on the water solubility of PCE and on the toxic effects of PCE on bacteria. The authors have also isolated PCE-resistant microorganisms from monitoring wells at Y-12. To date all of the PCE-resistant bacteria isolated from the monitoring wells have been of the genus Bacillus. One of these isolates appears to be able to degrade PCE, as indicated by the disappearance of PCE from cultures of growing cells. The organism does not grow on PCE as the sole carbon source, so degradation of the solvent must occur by cometabolism.

Hadden, C.T.; Benson, S.B.; Osborne, T.R.; Revis, N.W.

1988-12-31

346

Hazardous organic compounds in groundwater near Tehran automobile industry.  

PubMed

Potential of groundwater contamination by trichloroethylene (TCE) and other volatile organic compounds VOCs near car industry was conducted in this study. TCE, PCE, toluene, xylene, dichloromethane, cyclohexane, n-hexane and n-pentane were detected in all groundwaters. Mean TCE levels in groundwater ranged from 124.37 to 1,035.9 ?g L?¹ with maximum level of 1,345.7 ?g L?¹. Due to the data obtained from conventional wastewater treatment in car factory the TCE removal efficiency was only 24 percent which necessitates the TCE removal by advanced treatment processes before the use of well water. PMID:21069286

Dobaradaran, Sina; Mahvi, Amir Hossein; Nabizadeh, Ramin; Mesdaghinia, Alireza; Naddafi, Kazem; Yunesian, Masoud; Rastkari, Noushin; Nazmara, Shahrokh

2010-11-11

347

Removing hexavalent chromium from subsurface waters with anion-exchange resin  

SciTech Connect

Some subsurface waters at Lawrence Livermore National Laboratory (LLNL) are contaminated with volatile organic compounds (VOCs). Hexavalent chromium, Cr(VI), is also present in the ground water; however, the source of the Cr(VI) may be natural. The Cr(VI) still must be treated if brought to the surface because its concentration exceeds discharge standards. We are planning facilities for removing the VOCs and Cr(VI) to a level below the discharge standards. The planned treatment includes the following steps: (1) Pumping the water to the surface facility. (2) Purging the VOCs with air and absorbing them on activated carbon. The VOCs in LLNL`s subsurface waters are primarily chlorinated organic solvents, such as dichloroethylene (DCE), trichloroethylene (TCE), perchloroethylene (PCE), and chloroform (CHCl{sub 3}). Contamination levels range from tens to thousands of parts per billion. (3) Filtering the water. (4) Passing the water through anion-exchange resin to remove the Cr. The Cr in LLNL subsurface waters occurs almost entirely as Cr(VI), which exists as the chromate anion, CrO{sub 4}{sup 2-}, at environmental pH. Cr levels range from tens to hundreds of parts per billion. (5) Discharging the treated water into the local arroyos. The relevant discharge criteria are 5 ppb total VOCs, 11 ppb Cr(VI), and pH between 6.5 and 8.5, inclusive. This report describes laboratory experiments undertaken to learn how the proposed treatment facility can be expected to operate. The laboratory results are expected to supply vendors with the detailed performance specifications needed to prepare bids on the Cr removal portion of the treatment facility. The treatment facility is expected to process 60 gallons per minute (gpm) of water by stripping VOCs with 720 standard cubic feet per minute (scfm) of air and removing Cr(VI) with 60 ft{sup 3} of resin.

Torres, R.A.

1995-06-01

348

DNAPLs at DOE sites: Background and assessment of characterization technologies  

SciTech Connect

The Characterization, Monitoring, and Sensor Technology Integrated Program (CMST-IP) within the Office of Technology Development (OTD) has responsibility for identification, evaluation, and delivery of technologies needed for the work of the Department of Energy`s Office of Environmental Restoration and Waste Management. This report addresses part of that responsibility by providing summary information on DNAPL site characterization. A dense nonaqueous phase liquid (DNAPL) is a source of contamination that can persist in the subsurface for decades before dissipating completely into the vapor phase and groundwater. The DNAPL chemicals of particular concern to the DOE are chlorinated volatile organic compounds (Cl VOCS) such as carbon tetrachloride (CCl{sub 4}), trichloroethylene (TCE), and perchloroethylene (PCE). These Cl VOCs were used in multiple ton quantities at DOE sites and were often released to the subsurface. The predicted fate of released Cl VOC liquid is downward movement through the soil under the force of gravity. As it moves, some of the Cl VOC liquid becomes trapped in the soil pores as residual saturation. The liquid also moves rapidly downward if small fractures are present. This migration continues until an impermeable or semi-permeable layer is encountered. Then lateral movement or spreading occurs. The downward and lateral migration in the subsurface leads to DNAPL pools, lenses, and residual saturation that can cause long-term contamination of groundwater at levels well above drinking water standards. Although Cl VOCs have been detected as dissolved components in the groundwater and as vapor in the soil gas at several DOE sites, direct evidence of their presence as DNAPL is sparse and no measurements of the amounts of DNAPL present within a given volume of subsurface have been made. Consequently, unresolved DNAPL issues exist at DOE sites.

Junk, G.A.; Haas, W.J. Jr.

1993-12-01

349

Development of an integrated, in-situ remediation technology. Draft topical report for task No. 9. Part II. Entitled: TCE degradation using non-biological methods, September 26, 1994--May 25, 1996  

SciTech Connect

Contamination in low permeability soils poses a significant technical challenge to in-situ remediation efforts. Poor accessibility to the contaminants and difficulty in delivery of treatment reagents have rendered existing in-situ treatments such as bioremediation, vapor extraction, pump and treat rather ineffective when applied to low permeability soils present at many contaminated sites. The technology is an integrated in-situ treatment in which established geotechnical methods are used to install degradation zones directly in the contaminated soil and electro-osmosis is utilized to move the contaminants back and forth through those zones until the treatment is completed. The use of zero valence iron for reductive dechlorination of aliphatic chlorinated hydrocarbons is currently under investigation by a number of research groups as a potential method of in-situ treatment of contaminated ground water. The reaction appears to involve the transfer of electrons to chloro-aliphatic compounds by the oxidation of zero valence iron to ferrous iron (Fe{sup +2}). Our studies have indicated that this reaction is consistent with those of corrosion, and as such, can be influenced or increased by the presence of small amounts of metals (5% by weight) such as copper, tin, silver, gold and palladium coated on the iron surface. Incomplete coverage of the iron surface with a more electropositive metal results in an open galvanic cell, which increases the oxidation of iron and facilitates and increases the concurrent reduction of trichloroethylene and other chlorinated aliphatic compounds to the corresponding alkenes and alkanes. Our results show that plating more electropositive metals onto certain iron surfaces results in approximately a factor of ten increase in the dechlorination rate of small organochlorine compounds such as TCE.

Orth, R.G.; McKenzie, D.E.

1997-04-01

350

Complete biological reductive transformation of tetrachloroethene to ethane  

SciTech Connect

Reductive dechlorination of tetrachloroethene (perchloroethylene; PCE) was observed at 20 C in a fixed-bed column, filled with a mixture of anaerobic sediment from the Rhine river and anaerobic granular sludge. In the presence of lactate as an electron donor, 9 [mu]M PCE was dechlorinated to ethene. Ethene was further reduced to ethane. Mass balances demonstrated an almost complete conversion, with no chlorinated compounds remaining. When the temperature was lowered to 10 C, an adaptation of 2 weeks was necessary to obtain the same performance as at 20 C. Dechlorination by column material to ethene, followed by a slow ethane production, could also be achieved in batch cultures. Ethane was not formed in the presence of bromoethanesulfonic acid, an inhibitor of methanogenesis. The high dechlorination rate, even at low temperatures and considerable PCE concentrations, together with the absence of chlorinated end products, makes reductive dechlorination an attractive method for removal of PCE in bioremediation processes.

Bruin, W.P. de; Kotterman, M.J.J.; Posthumus, M.A.; Schraa, G.; Zehnder, A.J.B. (Wageningen Agricultural Univ. (Netherlands))

1992-06-01

351

Dechlorination of TCE with palladized iron  

DOEpatents

The present invention relates to various methods, such as an above-ground method and an in-ground method, of using a palladized iron bimetallic system for the dechlorination of chlorinated organic compounds from effluents containing the same. The use of palladized iron bimetallic system results in the dechlorination of the chlorinated organic compound into environmentally safe reaction products. The present invention also provides kits, devices, and other instruments that use the above-mentioned palladized iron bimetallic system for the dechlorination of chlorinated organic compounds.

Fernando, Quintus (Tucson, AZ); Muftikian, Rosy (Tucson, AZ); Korte, Nic (Grand Junction, CO)

1997-01-01

352

Dechlorination of TCE with palladized iron  

DOEpatents

The present invention relates to various methods, such as an above-ground method and an in-ground method, of using a palladized iron bimetallic system for the dechlorination of chlorinated organic compounds from effluents containing the same. The use of palladized iron bimetallic system results in the dechlorination of the chlorinated organic compound into environmentally safe reaction products. The present invention also provides kits, devices, and other instruments that use the above-mentioned palladized iron bimetallic system for the dechlorination of chlorinated organic compounds.

Fernando, Quintus (Tucson, AZ); Muftikian, Rosy (Tucson, AZ); Korte, Nic (Grand Junction, CO)

1998-01-01

353

Dechlorination of TCE with palladized iron  

DOEpatents

The present invention relates to various methods, such as an above-ground method and an in-ground method, of using a palladized iron bimetallic system for the dechlorination of chlorinated organic compounds from effluents containing the same. The use of palladized iron bimetallic system results in the dechlorination of the chlorinated organic compound into environmentally safe reaction products. The present invention also provides kits, devices, and other instruments that use the above-mentioned palladized iron bimetallic system for the dechlorination of chlorinated organic compounds. 10 figs.

Fernando, Q.; Muftikian, R.; Korte, N.

1997-03-18

354

Developing strategies for PAH and TCE bioremediation  

SciTech Connect

Bioremediation is the controlled use of microbes, commonly bacteria and fungi, to reclaim soil and water contaminated with substances that are deleterious to human health and the environment. The organisms used often naturally inhabit the polluted matrix; however, they may inhabit a different environment and be used as seed organisms because of their ability to degrade a specific class of substances. It is because of the wide diversity of microbial metabolic potential that bioremediation is possible. Polyaromatic hydrocarbons (PAHs) are organic compounds that are ubiquitous in the environment. They are present in fossil fuels and are formed during the incomplete combustion of organic material. PAHs exhibit low volatility and low aqueous solubility. As the molecular weight of these compounds increases, there is an exponential decrease in solubility and volatility. PAHs tend to adsorb onto soils and sediments because of their hydrophobic character, which is an intrinsic function of molecular size. The microbial degradation of individual PAHs by pure cultures and mixed populations occurs under a wide range of soil types and environmental conditions. Generally, the factors having the greatest influence on PAH biodegradation rates are soil moisture content, pH, inorganic nutrients present, PAH loading rates, initial PAH concentrations, and the presence of an acclimated microbial population. Feasibility studies are essential for developing a bioremediation strategy and are performed in a phased testing program that is designed to accomplish a number of objectives. These objectives include establishing an indigenous microbial population that will degrade specific contaminants, defining the rate-limiting factors for enhanced PAH degradation and the optimal treatment in terms of rates and cleanup levels attainable, and developing design parameters for field operations.

Mahaffey, W.R.; Nelson, M.; Kinsella, J. (Ecova Corp., Redmond, WA (United States)); Compeau, G. (Applied Geosciences, Inc., Bellevue, WA (United States))

1991-10-01

355

Identification of a reductive tetrachloroethene dehalogenase in Shewanella sediminis.  

PubMed

The genome sequence of psychrophilic Shewanella sediminis revealed the presence of five putative reductive dehalogenases (Rdhs). We found that cell extracts of pyruvate/fumarate-grown S. sediminis cells catalysed reduced methyl viologen-dependent reductive dechlorination of tetrachloroethene (PCE) to trichloroethene (TCE) at a specific activity of approximately 1 nmol TCE min(-1) (mg protein)(-1). Dechlorination of PCE followed Michaelis-Menten kinetics with an apparent Km of 120 ?M PCE. No PCE dechlorination was observed with heat-denatured extract or when cyanocobalamin was omitted from the growth medium; however, the presence of PCE in the growth medium increased PCE transformation rates. Analysis of mutants carrying in-frame deletions of all five Rdhs encoding genes showed that only deletion of Ssed_3769 resulted in the loss of PCE dechlorination activity suggesting that Ssed_3769 is a functional Rdh. This is the first study to show reductive dechlorination activity of PCE in a sediment-dwelling Shewanella species that may be important for linking the flux of organohalogens to organic carbon via reductive dehalogenation in marine sediments. PMID:23479755

Lohner, Svenja T; Spormann, Alfred M

2013-03-11

356

A microcosm test for potential mineralization of chlorinated compounds under coupled aerobic/anaerobic conditions.  

PubMed

In this study, the feasibility of using a mineralization test under coupled aerobic/anaerobic conditions was demonstrated. The coupling of anaerobic methanogenic and aerobic methanotrophic conditions in a microcosm required the presence of both a carbon source for anaerobic metabolism and oxygen for aerobic metabolism. These requirements were fulfilled by using a slow hydrolyzing organic matter along with intermittent addition of oxygen to the bottle headspace. Perchloroethylene (PCE) mineralization tests confirmed the effectiveness of the proposed methodology as well as PCE mineralization under coupled conditions. PMID:12079064

Lyew, D; Tartakovsky, B; Manuel, M F; Guiot, S R

2002-05-01

357

Reductive dechlorination of chlorinated ethenes and 1,2-dichloroethane by Dehalococcoides ethenogenes'' 195  

Microsoft Academic Search

Dehalococcoides ethenogenes'' 195 can reductively dechlorinate tetrachloroethene (PCE) completely to ethene (ETH). When PCE-grown strain 195 was transferred (2% [vol\\/vol] inoculum) into growth medium amended with trichloroethene (TCE), cis-dichloroethene (DCE), 1,1-DCE, or 1,2-dichloroethane (DCA) as an electron acceptor, these chlorinated compounds were consumed at increasing rates over time, which indicated that growth occurred. Moreover, the number of cells increased when

X. Maymo-Gatell; TIMOTHY ANGUISH; STEPHEN H. ZINDER

1999-01-01

358

Use of Mini-Sprinklers to Strip Trichloroethylene and Tetrachloroethylene from Contaminated Ground Water  

Microsoft Academic Search

Berisford, Y.C., P.B. Bush, J.I. Blake, and C.L. Bayer. 2003. Use of mini-sprinklers to strip trichloroethylene and tetrachloroethylene from contaminated ground water. J. Env. Qual. 32:801-815.;\\u000a;\\u000aThree low-volume mini-sprinklers were tested for their efficacy to strip trichloroethylene (TCE) and tetrachloroethylene (PCE) from water. Deionized water spiked with TCE and PCE was pumped through a mini-sprinkler supported on top of

Brerisford; C. Yvette; B. Parshall; John Blake; Cassandra L. Bayer

2003-01-01

359

Composition Dependent Evolution in Mass Flux from Binary Trichloroethene/Tetrachloroethene-DNAPL Source Zones  

NASA Astrophysics Data System (ADS)

In order to accurately predict the efficacy of subsurface remediation for sites contaminated with multicomponent dense non-aqueous phase liquids (DNAPLs), it is necessary to link changes in aqueous phase contaminant discharge with source composition and distribution. Dissolution from a binary 1:1 (molar) mixture of trichloroethene- (TCE) and tetrachloroethene- (PCE) DNAPL was measured in three separate 2-dimensional aquifer cells (100 x 48 x 1.4 cm) that were packed with different background media (1:1 mixture 20:30 and 40:50 mesh; 20:30 mesh and 40:50 mesh Accusand) and low permeability zones. Initial DNAPL source zone architectures were varied to yield ganglia to pool (GTP) ratios of 0.44, 1.56, and 1.72. Down-gradient plume evolution and DNAPL spatial distribution were measured every 5 pore volumes (PV) from side port samples and a light transmission system that allowed non-invasive measurement of volumetric DNAPL saturation and source descriptive metrics at a resolution of 0.03 to 0.08 mm2. Flux-averaged PCE and TCE effluent concentrations were measured every 0.7 PVs from a fully screened effluent chamber. To accelerate changes in source zone architecture and overall mass removal, two surfactant floods (4% w/w Tween 80) were completed after mass discharge from the source zone reached a steady state. Mass flux reductions for a given amount of DNAPL mass removed were found to correspond strongly to the molar composition of DNAPL in the source zone and the initial DNAPL saturation distribution metric (e.g., GTP). Percent reductions in mass flux from the aquifer cells with ganglia dominated architectures were 98 and 72% for TCE and PCE respectively, with a final overall NAPL source zone molar ratio of 0.49:0.51 TCE: PCE ; and 97 and 79% for TCE and PCE with molar ratios of 0.19:0.81 TCE:PCE. Reductions in mass flux from the pool dominated source zone were 90 and 53% for TCE and PCE with a final overall DNAPL source zone mole fraction of 0.26:0.74 TCE:PCE. These results indicate that observed mass flux reductions have to be considered with respect to the composition and distribution of DNAPL source zones in heterogeneous subsurface environments.

Walker, D. I.; Cápiro, N. L.; Granbery, E. K.; Pennell, K. D.

2010-12-01

360

Bubbleless gas transfer technology for the in situ remediation of chlorinated hydrocarbons  

SciTech Connect

The primary objective of this project is to demonstrate the ability of hydrogen to supply reducing equivalents for the reductive dehalogenation of perchloroethylene (PCE). This objective will be accomplished by two types of activities. First, laboratory experiments will compare the kinetics of hydrogen-mediated dehalogenation with natural routes of loss (hydrolysis and natural attenuation). Secondly, bench-scale column experiments will be performed to demonstrate hydrogen-mediated reductive dehalogenation in aquifer sediments.

Gallagher, J.R.; Kurz, M.D.

1999-10-31

361

Comparison of Chlorinated Ethenes DNAPL Reductive Dechlorination by Indigenous and Evanite culture with Surfactant Tween-80  

NASA Astrophysics Data System (ADS)

Although many innovative technologies have been developed to enhance remediation of chlorinated ethenes(e.g. tetrachloroethene[PCE], trichloroethene[TCE])DNAPL source zones, they have been ineffective in reducing contaminant concentration to regulatory end points. Thus, combination of surfactant flushing process that removes significant contaminant mass with microbial reductive dechlorination, posttreatment "polishing step" to control the remaining DNAPL that may serve as a source of reducing equivalents and stimulate the dechlorinating bacterial communities may be an attractive remediation process alternatively. Microcosm studies were conducted to explore chlorinated ethenes, PCE/TCE of 3 ~ 30 mg/L dechlorination by indigenous microbial communities from TCE DNAPL source zones of Korea and Evanite culture in the presence of Tween-80 of 10 ~ 5,000 mg/L. In the microcosms for indigenous microbial communities, by-products(e.g. c-DCE, vinyl chloride) of reductive dechlorination of PCE/TCE were not detected. This results suggest dechlorinating bacteria might be not exist or high concentration of chlorinated ethenes inhibit activity of dechlorinating bacteria in indigenous microbial communities. But VFAs like acetate, methane and hydrogen gas from fermentation of Tween-80 were detected. So Tween-80 might estimated to serve as a source of reducing equivalents. To evaluate the dechlorinating ability of Evanite-culture, we added Evanite-culture to the microcosms for indigenous bacteria and monitored by-products of reductive dechlorination of PCE/TCE and VFAs and hydrogen gas.

Kwon, S.; Hong, S.; Kim, R.; Kim, N.; Ahn, H.; Lee, S.; Kim, Y.

2010-12-01

362

Permanganate oxidation of DNAPL in a large 3-D flow tank  

Microsoft Academic Search

Potassium permanganate (KMnO4), as a metal-oxo reagent, can attack a double carbon-carbon bond and therefore oxidize common chlorinated ethylenes, such as trichloroethylene (TCE) and tetrachloroethylene (PCE). This feature of metal-oxo reagents facilitates the use of permanganate to remediation of chlorinated solvents in soil and groundwater. In this study, we evaluated the efficiency of TCE removal by permanganate oxidation in large

E. Lee; Y. Seol; Y. C. Fang; F. W. Schwartz

2002-01-01

363

Kinetic and isotope analyses of tetrachloroethylene and trichloroethylene degradation by model Fe(II)-bearing minerals.  

PubMed

The kinetics and in some cases stable carbon isotope fractionation associated with abiotic reductive dechlorination of tetrachloroethylene (PCE) and trichloroethylene (TCE) by model Fe(II)-bearing minerals present in anaerobic soils were measured. The minerals studied were chloride green rust (GR-Cl), sulfate green rust (GR-SO(4)), pyrite, magnetite, and adsorbed Fe(II) or FeS formed at the surface of goethite by treatment with dissolved Fe(II) or S(-II). We observed some abiotic transformation of PCE and TCE in every system studied, as evidenced by the presence of abiotic reaction products. Bulk enrichment factors (epsilon(bulk) values) for TCE transformation by GR-Cl and pyrite were -23.0+/-1.8 per thousand and -21.7+/-1.0 per thousand, respectively, which are more negative than reported values for microbial TCE dechlorination and could provide one means for distinguishing microbial from abiotic dechlorination of TCE in the environment. Considering the time scale of subsurface remediation technologies, including natural attenuation, minerals such as green rusts, pyrite, and magnetite have the potential to contribute to the transformation of PCE and TCE at contaminated sites. PMID:19111888

Liang, Xiaoming; Philp, R Paul; Butler, Elizabeth C

2008-12-27

364

A highly purified enrichment culture couples the reductive dechlorination of tetrachloroethene to growth.  

PubMed Central

A microscopically pure enrichment culture of a gram-negative anaerobic bacterium, in the present article referred to as PER-K23, was isolated from an anaerobic packed-bed column in which tetrachloroethene (PCE) was reductively transformed to ethane via trichloroethene (TCE), cis-1,2-dichloroethene (cis-1,2-DCE), chloroethene, and ethene. PER-K23 catalyzes the dechlorination of PCE via TCE to cis-1,2-DCE and couples this reductive dechlorination to growth. H2 and formate were the only electron donors that supported growth with PCE or TCE as an electron acceptor. The culture did not grow in the absence of PCE or TCE. Neither O2, NO3-, NO2-, SO4(2-), SO3(2-), S2O3(2-), S, nor CO2 could replace PCE or TCE as an electron acceptor with H2 as an electron donor. Also, organic electron acceptors such as acetoin, acetol, dimethyl sulfoxide, fumarate, and trimethylamine N-oxide and chlorinated ethanes, DCEs, and chloroethene were not utilized. PER-K23 was not able to grow fermentatively on any of the organic compounds tested. Transferring the culture to a rich medium revealed that a contaminant was still present. Dechlorination was optimal between pH 6.8 and 7.6 and a temperature of 25 to 35 degrees C. H2 consumption was paralleled by chloride production, PCE degradation, cis-1,2-DCE formation, and growth of PER-K23. Electron balances showed that all electrons derived from H2 or formate consumption were recovered in dechlorination products and biomass. Exponential growth could be achieved only in gently shaken cultures.(ABSTRACT TRUNCATED AT 250 WORDS) Images

Holliger, C; Schraa, G; Stams, A J; Zehnder, A J

1993-01-01

365

Natural attenuation of chlorinated solvents at Area 6, Dover Air Force Base: groundwater biogeochemistry  

Microsoft Academic Search

Monitored natural attenuation (MNA) has recently emerged as a viable groundwater remediation technology in the United States. Area 6 at Dover Air Force Base (Dover, DE) was chosen as a test site to examine the potential for MNA of tetrachloroethene (PCE) and trichloroethene (TCE) in groundwater and aquifer sediments. A “lines of evidence” approach was used to document the occurrence

Michael E. Witt; Gary M. Klecka; Edward J. Lutz; Tom A. Ei; Nancy R. Grosso; Francis H. Chapelle

2002-01-01

366

Anionic surfactant remediation of soil columns contaminated by nonaqueous phase liquids  

Microsoft Academic Search

A variety of column experiments have been completed for the purpose of selecting and evaluating suitable surfactants for remediation of nonaqueous phase liquids (NAPLs). The various NAPLs tested in the laboratory experiments were tetrachloroethylene (PCE), trichloroethylene (TCE), jet fuel (JP4) and a dense nonaqueous phase liquid from a site at Hill Air Force Base, UT. Both Ottawa sand and Hill

V. Dwarakanath; K Kostarelos; Gary A Pope; Doug Shotts; William H Wade

1999-01-01

367

Elimination of Chlorinated Unsaturated Hydrocarbons from Water by Ozonation. Simulation and Experimental Data Compariso n  

Microsoft Academic Search

The decomposition of chlorinated unsaturated hydroca r - bons in water by ozone at constant pressure and temperature (20 ºC ) was realized experimentally in a semi-batch reactor (250-mL) in di s - tilled water. The compounds were trichloroethylene (TCE) and tetr a - chloroethylene (PCE). The kinetics of the pollutant ozonation is pr o - posed in a mathematical

Tatiana I. Poznyak; A. Manzo; José Luis Mayorg

2003-01-01

368

ANNUAL REPORT. DEVELOPMENT OF RADON AS A NATURAL TRACER FOR MONITORING THE REMEDIATION OF NAPL CONTAMINATION IN THE SUBSURFACE  

EPA Science Inventory

Dense non-aqueous phase liquids (DNAPLs) such as trichloroethene (TCE) and perchloroethene (PCE) present long-term challenges in terms of quantification in the subsurface at many DOE facilities. Over the past year we have continued investigating a potentially lower-cost method fo...

369

Aerobic/anaerobic/aerobic sequenced biodegradation of a mixture of chlorinated ethenes, ethanes and methanes in batch bioreactors.  

PubMed

A novel aerobic/anaerobic/aerobic treatment was implemented in batch reactors containing aquifer materials from a site contaminated by tetrachloroethylene (PCE), trichloroethylene (TCE), vinyl chloride (VC), 1,1,2-trichloroethane (1,1,2-TCA) and chloroform (CF). Consortia grown aerobically on methane, propane, n-pentane and n-hexane completely biodegraded the chlorinated solvent mixture, via aerobic cometabolism of VC, CF, TCE and 1,1,2-TCA, followed by PCE reductive dechlorination (RD) to 1,2-cis-dichlorothylene (cis-DCE) or TCE, and cis-DCE/TCE cometabolism in a further aerobic phase. n-Hexane was the best substrate. No electron donor was supplied for RD, which likely utilized cellular material produced during the aerobic phase. Chloride release was stoichiometric with chlorinated solvent biodegradation. According to the Lepidium sativum ecotoxicity test, a decreased toxicity was observed with propane, n-pentane and n-hexane, but not methane. A kinetic study of PCE RD allowed to estimate the PCE maximum specific rate (0.57 ± 0.07 mg mg(protein)(-1) day(-1)) and half-saturation constant (6.7 ± 1.5 mg L(-1)). PMID:23201903

Frascari, Dario; Fraraccio, Serena; Nocentini, Massimo; Pinelli, Davide

2012-10-17

370

Quantification of groundwater contamination in an urban area using integral pumping tests  

Microsoft Academic Search

In this paper, the integral groundwater investigation method is used for the quantification of PCE and TCE mass flow rates at an industrialized urban area in Linz, Austria. In this approach, pumping wells positioned along control planes perpendicular to the groundwater flow direction are operated for a time period on the order of days and sampled for contaminants. The concentration

S. Bauer; M. Bayer-Raich; T. Holder; C. Kolesar; D. Müller; T. Ptak

2004-01-01

371

Test plan for single well injection\\/extraction characterization of DNAPL  

Microsoft Academic Search

Soils and groundwater beneath an abandoned Process sewer line in the A\\/M Area of the Savannah River Site (SRS) contain elevated levels of volatile organic compounds, specifically trichloroethylene (TCE) and tetrachloroethylene (PCE), two common chlorinated solvents. These compounds have low aqueous solubilities, thus when released to the subsurface in sufficient quantity, tend to exist as immiscible fluids or nonaqueous phase

B. B. Looney; K. M. Jerome; S. Burdick; J. Rossabi; T. R. Jarosch; C. A. Eddy-Dilek

1995-01-01

372

Test plan for Geo-Cleanse{reg_sign} demonstration (in situ destruction of dense non-aqueous phase liquid (DNAPL))  

Microsoft Academic Search

Soils and groundwater beneath an abandoned process sewer line in the A\\/M Area of the Savannah River Site (SRS) contain elevated levels of volatile organic compounds, specifically trichloroethylene (TCE) and tetrachloroethylene (PCE), two common chlorinated solvents. These compounds have low aqueous solubilities, thus when released to the subsurface in sufficient quantity, tend to exist as immiscible fluids or nonaqueous phase

K. M. Jerome; B. B. Looney; F. Accorsi; M. Dingens; J. T. Wilson

1996-01-01

373

Competition for hydrogen within a chlorinated solvent dehalogenating anaerobic mixed culture  

Microsoft Academic Search

Use of an appropriate hydrogen level is necessary to favor dehalogenation of chlorinated solvents, such as tetrachloroethene (PCE) and trichloroethene (TCE), over other hydrogen using processes. This study examined the competition between dehalogenators and other microorganisms occurring in a benzoate-acclimated dehalogenating methanogenic mixed culture. Results show that the dehalogenators competed best against methanogens and homoacetogens when the hydrogen level was

Yanru Yang; Perry L. McCarty

1998-01-01

374

Estimating DNAPL composition and VOC dilution from extraction well data  

Microsoft Academic Search

Field data from a large-scale ground-water extraction system at the Savannah River Site in South Carolina indicate that considerable dilution of volatile organic compounds (VOCs) occurs at extraction wells when compared with the effective solubilities of the VOC components (TCE and PCE) in the dense, nonaqueous phase liquid (DNAPL) source zone. This dilution is believed to be due to the

R. E. Jackson; P. E. Mariner

1995-01-01

375

INVESTIGATION OF CHLORINATED METHANES TREATABILITY USING ACTIVATED SODIUM PERSULFATE  

Microsoft Academic Search

In situ chemical oxidation is a frequently used remedial approach for the destruction of chlorinated ethenes such as tetrachloroethene (PCE) and trichloroethene (TCE). However, treatment of more recalcitrant chloroethanes and chloromethanes have challenged traditional oxidation reagents. Recently, new methods of sodium persulfate reagent activation have been developed and these systems have shown promise for improved treatment performance. The new methods

Duane K. Root; Ellen M. Lay; Philip A. Block; William G. Cutler

2005-01-01

376

Using (222)Rn as a naturally occurring tracer to estimate NAPL contamination in an aquifer.  

PubMed

The naturally occurring radioisotope (222)Rn was used as a partitioning tracer to evaluate the presence and amount of a non-aqueous phase liquid (NAPL) in an aquifer. The batch experiment results of a diesel contaminated soil showed that the emanation rate of (222)Rn decreased to 31%, relative to a background rate. Batch experiment results of water contaminated by gasoline, diesel, PCE and TCE were similar. A field study to examine TCE contamination was conducted using 54 groundwater samples in Wonju city, Republic of Korea. Estimates of TCE contamination ranged from <0.001mg/L to 14.3mg/L, and (222)Rn concentrations ranged from 1.89Bq/L to 444. Results of (222)Rn analysis showed that TCE contamination was mainly restricted to an asphalt laboratory area and that the (222)Rn values of a NAPL-contaminated aquifer were correlated with TCE analytical results. PMID:23602707

Yoon, Yoon Yeol; Koh, Dong Chan; Lee, Kil Yong; Cho, Soo Young; Yang, Jae Ha; Lee, Kang Kun

2013-04-04

377

Detection and monitoring of chlorinated solvent contamination by thermal neutron logging  

SciTech Connect

Thermal neutron logging is used to determine water content by measuring the elastic scattering due to hydrogen present in rocks and soils. The response of a thermal neutron device is also affected by the radiative capture of thermal neutrons by all elements. Chlorine has a large capture cross section in comparison to other elements usually found in aquifers; therefore, theory predicts that thermal neutron devices should respond to the presence of chlorinated solvents. Thermal neutron logging performed during a controlled release of perchloroethylene (PCE) confirmed that these methods can be used successfully to detect and monitor chlorinated solvents in the subsurface. To quantify the field results, a series of laboratory tests assessed the response of a neutron moisture probe used in the field experiments. These tests show that this device is very sensitive to the presence of chlorine and provide a basis for converting its response into an apparent PCE saturation. These saturation values compare favorably with PCE saturations obtained from core samples.

Endres, A.L.; Greenhouse, J.P. [Univ. of Waterloo, Ontario (Canada)

1996-03-01

378

Recognition and quantitation of closely related chlorinated organic vapors with acoustic-wave chemical sensor arrays  

NASA Astrophysics Data System (ADS)

An array of four acoustic wave chemical sensors has been developed and tested for recognition and quantitation of six closely related chlorinated organic vapors at low part-per- million concentrations. These vapors include PCE, TCE, VC, and DCE, cis-1,2-DCE, trans-1,2-DCE, and 1,1-DCE. The developed sensor array can detect as little as 0.2 ppm of PCE, 0.8 ppm of TCE, 1.4 ppm of cis-1,2-DCE, 1.4 ppm of trans-1,2-DCE, 3 ppm of 1,1-DCE, and 3.5 ppm of VC in air. Quantitation of TCE and cis-1,2-DCE vapor mixtures was achieved using multivariate calibration techniques. The locally weighted regression analysis provides more accurate results over the partial least squares regression.

Potyrailo, Radislav A.; May, Ralph J.; Sivavec, Timothy M.

1999-11-01

379

Biomonitoring study of dry cleaning workers using cytogenetic tests and the comet assay.  

PubMed

Perchloroethylene (PCE) is the main solvent used in the dry cleaning industry worldwide. The aim of the present work was to evaluate the genotoxic potential of occupational exposure to PCE in dry cleaning workers. The study was carried out in 59 volunteers (30 workers, 29 controls). The genotoxic effect was evaluated by analyzing chromosome aberrations (CAs), and micronuclei (MN) and DNA damage (assessed by the comet assay) in peripheral blood lymphocytes. Environmental monitoring of exposure was carried out on personal breathing zone air samples collected during two consecutive working days by measuring the concentration of PCE air levels. The mean PCE concentration in workplace air of dry cleaning workers was 31.40 mg/m(3). There were no significant differences in CA frequency between dry cleaning workers and the controls, but analysis showed a significant association of CA frequency with employment duration and frequency of exposure to PCE. The MN frequency and DNA damage detected by alkaline comet assay were significantly increased in dry cleaning workers compared to the controls. The results suggest that (a) chronic occupational exposure to dry cleaning solvents below permissible occupational exposure limit of 70 mg/m(3) (i.e., ?10.3 ppm) may lead to an increased risk of genetic damage among dry cleaning workers, and (b) CA, MN tests, and comet assay are useful to monitor populations exposed to low doses of PCE. PMID:24116666

Everatt, R?ta; Slapšyt?, Gražina; Mierauskien?, J?rat?; Dedonyt?, Veronika; Bakien?, Liuda

2013-11-01

380

Partition behavior of surfactants, butanol, and salt during application of density-modified displacement of dense non-aqueous phase liquids.  

PubMed

Density-modified displacement (DMD) is a recent approach for removal of trapped dense NAPL (DNAPL). In this study, butanol and surfactant are contacted with the DNAPL to both reduce the density as well as release the trapped DNAPL (perchloroethylene: PCE). The objective of the study was to determine the distribution of each component (e.g., butanol, surfactant, water, PCE) between the original aqueous and PCE phases during the application of DMD. The results indicated that the presence of the surfactant increased the amount of n-butanol required to make the NAPL phase reach its desired density. In addition, water and anionic surfactant were found to partition along with the BuOH into the PCE phase. The water also found partitioned to reverse micelles in the modified phase. Addition of salt was seen to increase partitioning of surfactant to BuOH containing PCE phase. Subsequently, a large amount of water was solubilized into reverse micelles which lead to significantly increase in volume of the PCE phase. This work thus demonstrates the role of each component and the implications for the operation design of an aquifer treatment using the DMD technique. PMID:23385206

Damrongsiri, S; Tongcumpou, C; Sabatini, D A

2013-01-16

381

Use of mini-sprinklers to strip trichloroethylene and tetrachloroethylene from contaminated ground water.  

PubMed

Three low-volume mini-sprinklers were tested for their efficacy to strip trichloroethylene (TCE) and tetrachloroethylene (PCE) from water. Deionized water spiked with TCE and PCE was pumped for approximately 1 h at 0.19 to 0.21 MPa (28 to 30 lb in(-2)) through a mini-sprinkler supported on top of a 1.8-m-tall riser. Water was collected in collection vessels at 0.61 and 1.22 m above the ground on support columns that were spaced at 0.61-m intervals from the riser base, and samples were composited per height and distance from the riser. Overall, air-stripping reduced dissolved concentrations of TCE and PCE by 99.1 to 100 and 96.9 to 100%, respectively, from mean influent dissolved concentrations of 466 to 1675 microg L(-1) TCE and 206 to 940 microg L(-1) PCE. In terms of mass removed, the mini-sprinklers removed TCE and PCE at a rate of approximately 1400 to 1700 and 700 to 900 microg L(-1), respectively, over a 1-h test period. Mini-sprinklers offer the advantages of (i) easy setup in series that can be used on practically any terrain; (ii) operation over a long period of time that does not threaten aquifer depletion; (iii) use in small or confined aquifers in which the capacity is too low to support large irrigation or purging systems; and (iv) use in forests in which the small, low-impact droplets of the mini-sprinklers do not damage bark and in which trees can help manage (via evapotranspiration) excess waste water. PMID:12809281

Berisford, Yvette C; Bush, Parshall B; Blake, John I; Bayer, Cassandra L

382

Estimates of anthropogenic halocarbon emissions based on its measured ratios relative to CO in the Pearl River Delta  

NASA Astrophysics Data System (ADS)

Using a GC/FID/MS system, we analyzed the mixing ratio levels of 16 halocarbon species in more than 100 air samples collected in 2004 from the Pearl River Delta (PRD) region of southern China. The results revealed elevated regional mixing ratios for most halocarbons, especially for HClC = CCl2 (trichloroethylene, TCE), CH2Cl2 (dichloromethane, DCM), CH3Br (bromomethane), HCFC-22, CHCl3 (trichloromethane), CCl4 (tetrachloromethane), Cl2C = CCl2 (perchloroethylene, PCE), CH3CCl3 (methyl chloroform, MCF), and CFC-12. Comparisons were done with the data from TRACE-P and ALE/GAGE/AGAGE experiments, we found that the large variability in concentrations (relative standard deviation ranged from 9.31% to 96.55%) of the halocarbons suggested substantial local emissions from the PRD region in 2004. Correlations between the mixing ratio of each species and carbon monoxide (CO) were examined, and then each emission of halocarbon was quantified based on scaling the optimized CO emission inventory with the slope of the regression line fitted to each species relative to CO. The calculated results revealed that mass of CH2Cl2 (7.0 Gg), CH3CCl3 (6.7 Gg), and Cl2C = CCl2 (2.3 Gg) accounted for about 62.9% of total emissions, suggesting a significant contribution to halocarbon emissions from solvent use in the PRD region. Emissions of HCFC-22 (3.5 Gg), an alternative refrigerant to chlorofluorocarbons (CFCs), were about 2.3 times greater than those of CFC-12 (1.6 Gg). CFC-12 and HCFC-22 accounted for 21.5% of total emissions of halocarbons, so that the refrigerant would be the second largest source of halocarbons. However, the ratio approach found only minor emissions of other CFCs, such as CFC-11, and levels of CFC-114 and CFC-113 were close to zero. Emissions of other anthropogenic halocarbons, such as CCl4, CHCl3, CH3Br, and CH3Cl, were also estimated. Where possible, the emissions estimated from the measured ratios were compared with results from source inventory techniques, we found that both approaches gave emissions at similar magnitude for most of the halocarbons, except CFC-11. The comparison suggested that ratio method may be a useful tool for assessing regional halocarbon emissions, and emission uncertainty could be further reduced by incorporating both longer-term and higher-frequency observations, as well as improving the uncertainty of the CO inventory.

Shao, M.; Huang, D. K.; Gu, D. S.; Lu, S. H.; Chang, C. C.; Wang, J.-L.

2011-01-01

383

Estimate of anthropogenic halocarbon emission based on measured ratio relative to CO in the Pearl River Delta region, China  

NASA Astrophysics Data System (ADS)

Using a GC/FID/MS system, we analyzed the mixing ratio of 16 halocarbon species in more than 100 air samples collected in 2004 from the Pearl River Delta (PRD) region of southern China. The results revealed that there are elevated mixing ratios for most of halocarbons, especially for HClC = CCl2 (trichloroethylene, TCE), CH2Cl2 (dichloromethane, DCM), CH3 Br (bromomethane), HCFC-22, CHCl3 (trichloromethane), CCl4 (tetrachloromethane), Cl2C = CCl2 (perchloroethylene, PCE), CH3CCl3 (methyl chloroform, MCF), and CFC-12. Comparisons were done with the data from TRACE-P and ALE/GAGE/AGAGE experiments, we found that the large variability in mixing ratios (relative standard deviation ranged from 9.31 % to 96.55 %) of the halocarbons suggested substantial local emissions from the PRD region in 2004. Correlations between the mixing ratio of each species and carbon monoxide (CO) was examined, and then the emission of each halocarbon was quantified based on scaling the optimized CO emission inventory with the slope of the regression line fitted to each species relative to CO. The calculated results revealed that mass of CH2Cl2 (7.0 Gg), CH3CCl3 (6.7 Gg), and Cl2C = CCl2 (2.3 Gg) accounted for about 62.9 % of total halocarbon emissions, it suggested a significant contribution from solvent use in the PRD region. Emissions of HCFC-22 (3.5 Gg), an alternative refrigerant to chlorofluorocarbons (CFCs), were about 2.3 times greater than those of CFC-12 (1.6 Gg). CFC-12 and HCFC-22 accounted for 21.5 % of total emissions of halocarbons, so that the refrigerant would be the second largest source of halocarbons. However, the ratio approach found only minor emissions of CFCs, such as CFC-11, and the emission of CFC-114 and CFC-113 were close to zero. Emissions of other anthropogenic halocarbons, such as CCl4, CHCl3, CH3Br, and CH3Cl, were also estimated. Where possible, the emissions estimated from the measured ratios were compared with results from source inventory techniques, we found that both approaches gave emissions at similar magnitude for most of the halocarbons, except CFC-11. The comparison suggested that the ratio method may be a useful tool for assessing regional halocarbon emissions, and emission uncertainty could be further reduced by incorporating both longer-term and higher-frequency observations, as well as improving the accuracy of the CO inventory.

Shao, M.; Huang, D.; Gu, D.; Lu, S.; Chang, C.; Wang, J.

2011-05-01

384

Removal of DNAPL contamination from the saturated zone by the combined effect of vertical upward flushing and density reduction.  

PubMed

A common aspect of innovative remediation techniques is that they tend to reduce the interfacial tension between the aqueous and non-aqueous phase liquids, resulting in mobilization of the organic contaminant. This complicates the remediation of aquifers, contaminated with Dense Non-Aqueous Phase Liquids (DNAPLs), as they are likely to migrate downwards, deeper into the aquifer and into finer layers. A possible solution is the use of swelling alcohols, which tend to reduce the density difference between the aqueous phase and the DNAPL. To avoid premature mobilization upon the initial contact between the DNAPL and the alcohol, several researchers have proposed the use of vertical upward flow of the alcohol. In this paper, we present an equation, which describes the upward mobilization of both continuous and discontinuous DNAPLs and so the important parameters governing the upward controlled mobilization of the DNAPL. The need and required magnitude of this specific discharge was investigated by conducting four column experiments in which the initial density of the DNAPL and the permeability was varied. It was shown that the required flow velocities increase with the permeability of the porous medium and the initial density difference between the aqueous phase and the DNAPL. Whenever the specific discharge falls below the critical value, the DNAPL moves downward. A second set of column experiments looked at the impact of permeability of porous medium on the solubilization and mobilization of DNAPL during alcohol flooding. Columns, packed with coarse or fine sand, containing a residual trichloroethylene (TCE) or perchloroethylene (PCE) saturation were flushed with the alcohol mixture at a fixed specific discharge rate. The induced pressure gradients in the aqueous phase, which were higher in the fine sand, resulted for this porous medium in extensive mobilization of the DNAPL against the direction of the buoyancy force. The density of the first NAPL coming out of the top of the fine sand was close to that of the pure DNAPL. In the coarser sand, the pressure gradients were sufficient to prevent downward migration of the DNAPL, but upward mobilization was minimal. The predominant removal mechanism in this case was the much slower solubilization. PMID:14607470

Hofstee, C; Gutiérrez Ziegler, C; Trötschler, O; Braun, J

2003-12-01

385

Translational research to develop a human PBPK models tool kit-volatile organic compounds (VOCs).  

PubMed

Toxicity and exposure evaluations remain the two of the key components of human health assessment. While improvement in exposure assessment relies on a better understanding of human behavior patterns, toxicity assessment still relies to a great extent on animal toxicity testing and human epidemiological studies. Recent advances in computer modeling of the dose-response relationship and distribution of xenobiotics in humans to important target tissues have advanced our abilities to assess toxicity. In particular, physiologically based pharmacokinetic (PBPK) models are among the tools than can enhance toxicity assessment accuracy. Many PBPK models are available to the health assessor, but most are so difficult to use that health assessors rarely use them. To encourage their use these models need to have transparent and user-friendly formats. To this end the Agency for Toxic Substances and Disease Registry (ATSDR) is using translational research to increase PBPK model accessibility, understandability, and use in the site-specific health assessment arena. The agency has initiated development of a human PBPK tool-kit for certain high priority pollutants. The tool kit comprises a series of suitable models. The models are recoded in a single computer simulation language and evaluated for use by health assessors. While not necessarily being state-of-the-art code for each chemical, the models will be sufficiently accurate to use for screening purposes. This article presents a generic, seven-compartment PBPK model for six priority volatile organic compounds (VOCs): benzene (BEN), carbon tetrachloride (CCl(4)), dichloromethane (DCM), perchloroethylene (PCE), trichloroethylene (TCE), and vinyl chloride (VC). Limited comparisons of the generic and original model predictions to published kinetic data were conducted. A goodness of fit was determined by calculating the means of the sum of the squared differences (MSSDs) for simulation vs. experimental kinetic data using the generic and original models. Using simplified solvent exposure assumptions for oral ingestion and inhalation, steady-state blood concentrations of each solvent were simulated for exposures equivalent to the ATSDR Minimal Risk Levels (MRLs). The predicted blood levels were then compared to those reported in the National Health and Nutrition Examination Survey (NHANES). With the notable exception of BEN, simulations of combined oral and inhalation MRLs using our generic VOC model yielded blood concentrations well above those reported for the 95th percentile blood concentrations for the U.S. populations, suggesting no health concerns. When the PBPK tool kit is fully developed, risk assessors will have a readily accessible tool for evaluating human exposure to a variety of environmental pollutants. PMID:22047160

Mumtaz, M Moiz; Ray, Meredith; Crowell, Susan R; Keys, Deborah; Fisher, Jeffrey; Ruiz, Patricia

2012-01-01

386

Microbial degradation of chloroethenes in groundwater systems  

NASA Astrophysics Data System (ADS)

The chloroethenes, tetrachloroethene (PCE) and trichloroethene (TCE) are among the most common contaminants detected in groundwater systems. As recently as 1980, the consensus was that chloroethene compounds were not significantly biodegradable in groundwater. Consequently, efforts to remediate chloroethene-contaminated groundwater were limited to largely unsuccessful pump-and-treat attempts. Subsequent investigation revealed that under reducing conditions, aquifer microorganisms can reductively dechlorinate PCE and TCE to the less chlorinated daughter products dichloroethene (DCE) and vinyl chloride (VC). Although recent laboratory studies conducted with halorespiring microorganisms suggest that complete reduction to ethene is possible, in the majority of groundwater systems reductive dechlorination apparently stops at DCE or VC. However, recent investigations conducted with aquifer and stream-bed sediments have demonstrated that microbial oxidation of these reduced daughter products can be significant under anaerobic redox conditions. The combination of reductive dechlorination of PCE and TCE under anaerobic conditions followed by anaerobic microbial oxidation of DCE and VC provides a possible microbial pathway for complete degradation of chloroethene contaminants in groundwater systems. Résumé Les chloroéthanes, tétrachloroéthane (PCE) et trichloroéthane (TCE) sont parmi les polluants les plus communs trouvés dans les aquifères. Depuis les années 1980, on considère que les chloroéthanes ne sont pas significativement biodégradables dans les aquifères. Par conséquent, les efforts pour dépolluer les nappes contaminées par des chloroéthanes se sont limités à des tentatives de pompage-traitement globalement sans succès. Des travaux ultérieurs ont montré que dans des conditions réductrices, des micro-organismes présents dans les aquifères peuvent, par réduction, dégrader les PCE et TCE en composés moins chlorés, comme le dichloréthane (DCE) et le chlorure de vinyl (VC). Bien que des études de laboratoire réalisées avec des micro-organismes adaptés aux composés halogénés montrent que la réduction complète en éthane est possible, dans la plupart des nappes la réaction de déchloration par réduction s'arrête apparemment au DCE et au VC. Cependant, des recherches récentes menées sur des sédiments d'un aquifère et d'alluvions ont démontré que l'oxydation microbienne de ces descendants réduits peut se produire de manière significative dans des conditions de redox anérobies. La déchloration par réduction de PCE et de TCE dans des conditions anérobies suivie par une oxydation microbienne anérobie des DCE et VC fournit une piste microbienne possible pour obtenir une dégradation complète des chloroéthanes polluants dans les aquifères. Resumen Los cloroetanos (tetracloroetano PCE y tricloroetano TCE) son contaminantes muy habituales en los acuíferos. Hasta 1980 se consideraba que los cloroetanos no eran biodegradables y, por tanto, los métodos de rehabilitación en acuíferos contaminados con cloroetanos se limitaban al pump-and-treat, generalmente con poco éxito. Posteriormente se vio que, en condiciones reductoras, algunos microorganismos pueden reducir PCE y TCE a unos subproductos menos clorados, como el dicloroetano (DCE) y el cloruro de vinilo (VC). Aunque estudios de laboratorio recientes sugieren que la reducción completa a etano es posible, en la mayoría de los sistemas acuíferos la decloración suele detenerse en los DCE o VC. Sin embargo, investigaciones más recientes en acuíferos y sedimentos fluviales demuestran que la oxidación microbiana de estos subproductos puede ser importante bajo condiciones redox anaerobias. La combinación de la reducción de PCE y TCE en condiciones anaerobias seguida de la oxidación microbiana anaerobia de DCE y VC proporciona un método potencial para la degradación total de los cloroetanos en los sistemas acuíferos.

Bradley, Paul M.

387

Reductive dechlorination of tetrachloroethylene and trichloroethylene catalyzed by vitamin B{sub 12} in homogeneous and heterogeneous systems  

SciTech Connect

The reduction of tetrachloroethylene (PCE) and trichloroethylene (TCE) catalyzed by vitamin B{sub 12} was examined in homogeneous and heterogeneous (B{sub 12} bound to agarose) batch systems using titanium(III) citrate as the bulk reductant. The solution and surface-mediated reaction rates at similar B{sub 12} loadings were comparable, indicating that binding vitamin B{sub 12} to a surface did not lower catalytic activity. No loss in PCE reducing activity was observed with repeated usage of surface-bound vitamin B{sub 12}. Carbon mass recoveries were 81-84% for PCE reduction and 89% for TCE reduction, relative to controls. In addition to sequential hydrogenolysis, a second competing reaction mechanism for the reduction of PCE and TCE by B{sub 12}, reductive {beta}-elimination, is proposed to account for the observation of acetylene as a significant reaction intermediate. Reductive {beta}-elimination should be considered as a potential pathway in other reactive systems involving the reduction of vicinal polyhaloethenes. Surface-bound catalysts such as vitamin B{sub 12} may have utility in the engineered degradation of aqueous phase chlorinated ethenes. 19 refs., 6 figs., 1 tab.

Burris, D.R.; Smith, M.H. [Armstrong Lab., Tyndall Air Force Base, FL (United States); Delcomyn, C.A. [Applied Research Associates, Inc., Tyndall Air Force Base, FL (United States); Roberts, A.L. [Johns Hopkins Univ., Baltimore, MD (United States)

1996-10-01

388

Characterization of Two Tetrachloroethene-Reducing, Acetate-Oxidizing Anaerobic Bacteria and Their Description as Desulfuromonas michiganensis sp. nov.  

PubMed Central

Two tetrachlorethene (PCE)-dechlorinating populations, designated strains BB1 and BRS1, were isolated from pristine river sediment and chloroethene-contaminated aquifer material, respectively. PCE-to-cis-1,2-dichloroethene-dechlorinating activity could be transferred in defined basal salts medium with acetate as the electron donor and PCE as the electron acceptor. Taxonomic analysis based on 16S rRNA gene sequencing placed both isolates within the Desulfuromonas cluster in the ? subdivision of the Proteobacteria. PCE was dechlorinated at rates of at least 139 nmol min?1 mg of protein?1 at pH values between 7.0 and 7.5 and temperatures between 25 and 30°C. Dechlorination also occurred at 10°C. The electron donors that supported dechlorination included acetate, lactate, pyruvate, succinate, malate, and fumarate but not hydrogen, formate, ethanol, propionate, or sulfide. Growth occurred with malate or fumarate alone, whereas oxidation of the other electron donors depended strictly on the presence of fumarate, malate, ferric iron, sulfur, PCE, or TCE as an electron acceptor. Nitrate, sulfate, sulfite, thiosulfate, and other chlorinated compounds were not used as electron acceptors. Sulfite had a strong inhibitory effect on growth and dechlorination. Alternate electron acceptors (e.g., fumarate or ferric iron) did not inhibit PCE dechlorination and were consumed concomitantly. The putative fumarate, PCE, and ferric iron reductases were induced by their respective substrates and were not constitutively present. Sulfide was required for growth. Both strains tolerated high concentrations of PCE, and dechlorination occurred in the presence of free-phase PCE (dense non-aqueous-phase liquids). Repeated growth with acetate and fumarate as substrates yielded a BB1 variant that had lost the ability to dechlorinate PCE. Due to the 16S rRNA gene sequence differences with the closest relatives and the unique phenotypic characteristics, we propose that the new isolates are members of a new species, Desulfuromonas michiganensis, within the Desulfuromonas cluster of the Geobacteraceae.

Sung, Youlboong; Ritalahti, Kirsti M.; Sanford, Robert A.; Urbance, John W.; Flynn, Shannon J.; Tiedje, James M.; Loffler, Frank E.

2003-01-01

389

Mixed Redox Catalytic Destruction of Chlorinated Solvents in Soils and Groundwater: From the Laboratory to the Field  

PubMed Central

A new thermocatalytic method to destroy chlorinated solvents has been developed in the laboratory and tested in a pilot field study. The method employs a conventional Pt/Rh catalyst on a ceramic honeycomb. Reactions proceed at moderate temperatures in the simultaneous presence of oxygen and a reductant (mixed redox conditions) to minimize catalyst deactivation. In the laboratory, stable operation with high conversions (above 90% at residence times shorter than 1 s) for perchloroethylene (PCE) is achieved using hydrogen as the reductant. A molar ratio of H2/O2 = 2 yields maximum conversions; the temperature required to produce maximum conversions is sensitive to influent PCE concentration. When a homologous series of aliphatic alkanes is used to replace hydrogen as the reductant, the resultant mixed redox conditions also produce high PCE conversions. It appears that the dissociation energy of the C–H bond in the respective alkane molecule is a strong determinant of the activation energy, and therefore the reaction rate, for PCE conversion. This new method was employed in a pilot field study in Tucson, Arizona. The mixed redox system was operated semicontinuously for 240 days with no degradation of catalyst performance and complete destruction of PCE and trichloroethylene in a soil vapor extraction gas stream. Use of propane as the reductant significantly reduced operating costs. Mixed redox destruction of chlorinated solvents provides a potentially viable alternative to current soil and groundwater remediation technologies.

Gao, Song; Rupp, Erik; Bell, Suzanne; Willinger, Martin; Foley, Theresa; Barbaris, Brian; Saez, A. Eduardo; Arnold, Robert G.; Betterton, Eric

2010-01-01

390

Mixed redox catalytic destruction of chlorinated solvents in soils and groundwater.  

PubMed

A new thermocatalytic method to destroy chlorinated solvents has been developed in the laboratory and tested in a pilot field study. The method employs a conventional Pt/Rh catalyst on a ceramic honeycomb. Reactions proceed at moderate temperatures in the simultaneous presence of oxygen and a reductant (mixed redox conditions) to minimize catalyst deactivation. In the laboratory, stable operation with high conversions (above 90% at residence times shorter than 1 s) for perchloroethylene (PCE) is achieved using hydrogen as the reductant. A molar ratio of H(2)/O(2)= 2 yields maximum conversions; the temperature required to produce maximum conversions is sensitive to influent PCE concentration. When a homologous series of aliphatic alkanes is used to replace hydrogen as the reductant, the resultant mixed redox conditions also produce high PCE conversions. It appears that the dissociation energy of the C-H bond in the respective alkane molecule is a strong determinant of the activation energy, and therefore the reaction rate, for PCE conversion. This new method was employed in a pilot field study in Tucson, Arizona. The mixed redox system was operated semicontinuously for 240 days with no degradation of catalyst performance and complete destruction of PCE and trichloroethylene in a soil vapor extraction gas stream. Use of propane as the reductant significantly reduced operating costs. Mixed redox destruction of chlorinated solvents provides a potentially viable alternative to current soil and groundwater remediation technologies. PMID:18991945

Gao, Song; Rupp, Erik; Bell, Suzanne; Willinger, Martin; Foley, Theresa; Barbaris, Brian; Sáez, A Eduardo; Arnold, Robert G; Betterton, Eric

2008-10-01

391

Characterization of the Corrinoid Iron-Sulfur Protein Tetrachloroethene Reductive Dehalogenase of Dehalobacter restrictus  

PubMed Central

The membrane-bound tetrachloroethene reductive dehalogenase (PCE-RDase) (PceA; EC 1.97.1.8), the terminal component of the respiratory chain of Dehalobacter restrictus, was purified 25-fold to apparent electrophoretic homogeneity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single band with an apparent molecular mass of 60 ± 1 kDa, whereas the native molecular mass was 71 ± 8 kDa according to size exclusion chromatography in the presence of the detergent octyl-?-d-glucopyranoside. The monomeric enzyme contained (per mol of the 60-kDa subunit) 1.0 ± 0.1 mol of cobalamin, 0.6 ± 0.02 mol of cobalt, 7.1 ± 0.6 mol of iron, and 5.8 ± 0.5 mol of acid-labile sulfur. Purified PceA catalyzed the reductive dechlorination of tetrachloroethene and trichloroethene to cis-1,2-dichloroethene with a specific activity of 250 ± 12 nkat/mg of protein. In addition, several chloroethanes and tetrachloromethane caused methyl viologen oxidation in the presence of PceA. The Km values for tetrachloroethene, trichloroethene, and methyl viologen were 20.4 ± 3.2, 23.7 ± 5.2, and 47 ± 10 ?M, respectively. The PceA exhibited the highest activity at pH 8.1 and was oxygen sensitive, with a half-life of activity of 280 min upon exposure to air. Based on the almost identical N-terminal amino acid sequences of PceA of Dehalobacter restrictus, Desulfitobacterium hafniense strain TCE1 (formerly Desulfitobacterium frappieri strain TCE1), and Desulfitobacterium hafniense strain PCE-S (formerly Desulfitobacterium frappieri strain PCE-S), the pceA genes of the first two organisms were cloned and sequenced. Together with the pceA genes of Desulfitobacterium hafniense strains PCE-S and Y51, the pceA genes of Desulfitobacterium hafniense strain TCE1 and Dehalobacter restrictus form a coherent group of reductive dehalogenases with almost 100% sequence identity. Also, the pceB genes, which may code for a membrane anchor protein of PceA, and the intergenic regions of Dehalobacter restrictus and the three desulfitobacteria had identical sequences. Whereas the cprB (chlorophenol reductive dehalogenase) genes of chlorophenol-dehalorespiring bacteria are always located upstream of cprA, all pceB genes known so far are located downstream of pceA. The possible consequences of this feature for the annotation of putative reductive dehalogenase genes are discussed, as are the sequence around the iron-sulfur cluster binding motifs and the type of iron-sulfur clusters of the reductive dehalogenases of Dehalobacter restrictus and Desulfitobacterium dehalogenans identified by electron paramagnetic resonance spectroscopy.

Maillard, Julien; Schumacher, Wolfram; Vazquez, Francisco; Regeard, Christophe; Hagen, Wilfred R.; Holliger, Christof

2003-01-01

392

Framework and Implementation of the Jyvaskyla TCE/TCFL Programmes.  

ERIC Educational Resources Information Center

|The first teacher in-service development program in foreign language content instruction was run by the Continuing Education Centre of the University of Jyvaskyla in 1991-1992 as a contract program for the City of Kokkola. The success of that program led to the development of the present Teaching Content in a Foreign Language (TCFL) Program,…

Marsh, David; Rasanen, Anne

393

Field testing solar photocatalytic detoxification on TCE-contaminated groundwater  

Microsoft Academic Search

The Solar Detoxification Field Experiment was designed to investigate the photocatalytic decomposition of organic contaminants in groundwater at a Superfund site at Lawrence Livermore National Laboratory. The process uses ultraviolet (UV) energy available in sunlight in conjunction with a photocatalyst, titanium dioxide, to decompose organic chemicals into nontoxic compounds. The destruction mechanism, as in many other advanced oxidation processes, involves

Mark S. Mehos; Craig S. Turchi

1993-01-01

394

On achievable service differentiation with token bucket marking for tce  

Microsoft Academic Search

Abstract The Differentiated services (diffserv) architecture has b een proposed as a scalable solution for providing service differentiation among,flows without any perflow buffer management,inside the core of the network. It has been advocated that it is feasible to prov ide service differentiation among,a set of flows by choosing an appropriate “marking profile” for each flo w. In this paper, we

S. Sahu; P. Nain; D. Towsley; C. Diot; V. Firoiu

1999-01-01

395

Microbial Composition Analysis for TCE Biostimulation and Bioremediation  

Microsoft Academic Search

Various molecular tools including real-time PCR, clone library, and automated ribosomal intergenic spacer analysis were used in this column study to analyze the change of microbial composition in response to the addition of various carbon donors and microbial inocula. Whey, emulsified oil and emulsified oil plus surfactant were used as carbon donors. According to the competitive electron accepting processes observed

Jing Zhou; R. Ryan Dupont; Jeanette M. Norton; Darwin L. Sorensen; Joan E. McLean

2008-01-01

396

Transaction Cost Economics (TCE) and Cost Estimation Methodology.  

National Technical Information Service (NTIS)

Hypothesis is that cost drivers are more complex than current methodology considers. Can a more complete view of costs improve cost estimation methodology. This briefing looks at methods of measuring transaction costs.

C. Franck D. Angelis F. Melese J. Dillard

2008-01-01

397

A review of potential neurotoxic mechanisms among three chlorinated organic solvents  

SciTech Connect

The potential for central nervous system depressant effects from three widely used chlorinated solvents, trichloroethylene (TCE), perchloroethylene (PERC), and dichloromethane (DCM), has been shown in human and animal studies. Commonalities of neurobehavioral and neurophysiological changes for the chlorinated solvents in in vivo studies suggest that there is a common mechanism(s) of action in producing resultant neurotoxicological consequences. The purpose of this review is to examine the mechanistic studies conducted with these chlorinated solvents and to propose potential mechanisms of action for the different neurological effects observed. Mechanistic studies indicate that this solvent class has several molecular targets in the brain. Additionally, there are several pieces of evidence from animal studies indicating this solvent class alters neurochemical functions in the brain. Although earlier evidence indicated that these three chlorinated solvents perturb the lipid bilayer, more recent data suggest an interaction between several specific neuronal receptors produces the resultant neurobehavioral effects. Collectively, TCE, PERC, and DCM have been reported to interact directly with several different classes of neuronal receptors by generally inhibiting excitatory receptors/channels and potentiating the function of inhibitory receptors/channels. Given this mechanistic information and available studies for TCE, DCM, and PERC, we provide hypotheses on primary targets (e.g. ion channel targets) that appear to be most influential in producing the resultant neurological effects. - Research Highlights: > Comparison of neurological effects among TCE, PERC, and DCM. > Correlation of mechanistic findings to neurological effects. > Data support that TCE, PERC, and DCM interact with several ion channels to produce neurological changes.

Bale, Ambuja S., E-mail: bale.ambuja@epa.gov; Barone, Stan; Scott, Cheryl Siegel; Cooper, Glinda S.

2011-08-15

398

Passive and active soil gas sampling at the Mixed Waste Landfill, Technical Area III, Sandia National Laboratories/New Mexico  

SciTech Connect

The Environmental Restoration Project at Sandia National Laboratories, New Mexico is tasked with assessing and remediating the Mixed Waste Landfill in Technical Area III. The Mixed Waste Landfill is a 2.6 acre, inactive radioactive and mixed waste disposal site. In 1993 and 1994, an extensive passive and active soil gas sampling program was undertaken to identify and quantify volatile organic compounds in the subsurface at the landfill. Passive soil gas surveys identified levels of PCE, TCE, 1,1, 1-TCA, toluene, 1,1,2-trichlorotrifluoroethane, dichloroethyne, and acetone above background. Verification by active soil gas sampling confirmed concentrations of PCE, TCE, 1,1,1-TCA, and 1,1,2-trichloro-1,2,2-trifluoroethane at depths of 10 and 30 feet below ground surface. In addition, dichlorodifluoroethane and trichlorofluoromethane were detected during active soil gas sampling. All of the volatile organic compounds detected during the active soil gas survey were present in the low ppb range.

McVey, M.D.; Goering, T.J. [GRAM, Inc., Albuquerque, NM (United States); Peace, J.L. [Sandia National Labs., Albuquerque, NM (United States)

1996-02-01

399

Gas phase photocatalytic degradation on TiO{sub 2} pellets of volatile chlorinated organic compounds from a soil vapor extraction well  

SciTech Connect

The mineralization of trichloroethylene (TCE) and tetrachloroethylene (PCE) in gas stream from a soil vapor extraction (SVE) well was demonstrated with an annular photocatalytic reactor packed with porous TiO{sub 2} pellets in field trials at the Savannah River Site in Aiken, SC. The TiO{sub 2} pellets were prepared using a sol-gel method. The experiments were performed at 55 to 60{degree}C using space times of 10{sup 8} to 10{sup 10} g s/mol for TCE and PCE. Chloroform (CHCl{sub 3}) and carbon tetrachloride (CCl{sub 4}) were detected as minor products from side reactions. On a molar basis, CCl{sub 4} and CHCl{sub 3} produced were about 2% and 0.2 % of the reactants.

Yamazaki-Nishida, S.; Read, H.W.; Nagano, J.K.; Anderson, M.A. [Wisconsin Univ., Madison, WI (United States). Water Chemistry Program; Cervera-March, S. [Barcelona Univ., (Spain). Department of Chemical Engineering; Jarosch, T.R.; Eddy-Dilek, C.A. [Westinghouse Savannah River Co., Aiken, SC (United States)

1993-05-20

400

FY02 Final Report on Phytoremediation of Chlorinated Ethenes in Southern Sector Sediments of the Savannah River Site  

SciTech Connect

This final report details the operations and results of a 3-year Seepline Phytoremediation Project performed adjacent to Tims Branch, which is located in the Southern Sector of the Savannah River Site (SRS) A/M Area. Phytoremediation is a process where interactions between vegetation, associated microorganisms, and the host substrate combine to effectively degrade contaminated soils, sediments, and groundwater. Phytoremediation is a rapidly developing technology that shows promise for the effective and safe cleanup of certain hazardous wastes. It has the potential to remediate numerous volatile organic compounds (VOCs). Extensive characterization work has demonstrated that two VOCs, tetrachloroethylene (PCE) and trichloroethylene (TCE) are the major components of the VOC-contaminated groundwater that is migrating through the Southern Sector and Tims Branch seepline area (WSRC, 1999). The PCE and TCE are chlorinated ethenes (CE), and have been detected in seepline soils and ground water adjacent to the ecologically-sensitive Tims Branch seepline area.

Brigmon, R..L.

2004-01-30

401

Comparison of anaerobic dechlorinating enrichment cultures maintained on tetrachloroethene, trichloroethene, cis-dichloroethene and vinyl chloride.  

PubMed

An anaerobic mixed microbial culture was enriched from soil and groundwater taken from a site contaminated with trichloroethene (TCE). This enrichment culture was divided into four subcultures amended separately with either perchloroethene (PCE), TCE, cis-dichloroethene (cDCE) or vinyl chloride (VC). In each of the four subcultures, the chlorinated ethenes were rapidly, consistently, and completely converted to ethene at rates of 30-50 micromol/l of culture per day, or an average 160 micro-electron equivalents/l of culture per day. These cultures were capable of sustained and rapid dechlorination of VC, and could not dechlorinate 1,2-dichloroethane, differentiating them from Dehalococcoides ethenogenes, the only known isolate capable of complete dechlorination of PCE to ethene. Chloroform (CF) and 1,1,1-trichloroethane, frequent groundwater co-contaminants with TCE and PCE, inhibited chlorinated ethene dechlorination. Most strongly inhibited was the final conversion of VC to ethene, with complete inhibition occurring at an aqueous CF concentration of 2.5 microM. Differences in rates and community composition developed between the different subcultures, including the loss of the VC enrichment culture's ability to dechlorinate PCE. Denaturing gradient gel electrophoresis of amplified bacterial 16S rRNA gene fragments identified three different DNA sequences in the enrichment cultures, all phylogenetically related to D. ethenogenes. Based on the PCR-DGGE results and substrate utilization patterns, it is apparent that significant mechanistic differences exist between each step of dechlorination from TCE to ethene, especially for the last important dechlorination step from VC to ethene. PMID:12420924

Duhamel, Melanie; Wehr, Stephan D; Yu, Lawrence; Rizvi, Homa; Seepersad, David; Dworatzek, Sandra; Cox, Evan E; Edwards, Elizabeth A

2002-10-01

402

A field comparison of two reductive dechlorination (zero-valent iron and lactate) methods  

Microsoft Academic Search

Two parallel pilot experiments were performed at Kurivody (Czech Republic) in order to compare two reductive remedial technologies for chlorinated ethenes – microbial dehalogenation assisted by lactate and chemical dehalogenation with zero-valent iron (nZVI) nanoparticles. The methods were applied at a site contaminated by tetrachlorethylene (PCE) and trichlorethylene (TCE), with total concentrations from 10 to 50 mg\\/l. Concentrations of chlorinated ethenes,

Lenka Lacinova; Petr Kvapil; Miroslav Cernik

2012-01-01

403

A field comparison of two reductive dechlorination (zero-valent iron and lactate) methods  

Microsoft Academic Search

Two parallel pilot experiments were performed at Kurivody (Czech Republic) in order to compare two reductive remedial technologies for chlorinated ethenes – microbial dehalogenation assisted by lactate and chemical dehalogenation with zero-valent iron (nZVI) nanoparticles. The methods were applied at a site contaminated by tetrachlorethylene (PCE) and trichlorethylene (TCE), with total concentrations from 10 to 50 mg\\/l. Concentrations of chlorinated ethenes,

Lenka Lacinova; Petr Kvapil; Miroslav Cernik

2011-01-01

404

Electrochemical SERS detection of chlorinated hydrocarbons in aqueous solutions  

Microsoft Academic Search

An [ital in] [ital situ] method for the determination of trichloroethylene (TCE), perchlorethylene (PCE), chloroform (CHCl[sub 3]) and carbon tetrachloride (CCl[sub 4]) in aqueous solution is described. The method is based on ESERS-a combination of electrochemical methods and surface-enhanced Raman scattering (SERS). Electrochemistry prepares the surface of a copper electrode for SERS and concentrates the analyte on the surface. The

John M. E. Storey; Robert D. Shelton; Tye E. Barber; Eric A. Wachter

1994-01-01

405

Characterization of microbial community structure and population dynamics of tetrachloroethene-dechlorinating tidal mudflat communities.  

PubMed

Tetrachloroethene (PCE) and trichloroethene (TCE) are common groundwater contaminants that also impact tidal flats, especially near urban and industrial areas. However, very little is known about dechlorinating microbial communities in tidal flats. Titanium pyrosequencing, 16S rRNA gene clone libraries, and dechlorinator-targeted quantitative real-time PCR (qPCR) characterized reductive dechlorinating activities and populations in tidal flat sediments collected from South Korea's central west coast near Kangwha. In microcosms established with surface sediments, PCE dechlorination to TCE began within 10 days and 100% of the initial amount of PCE was converted to TCE after 37 days. cis-1,2-Dichloroethene (cis-DCE) was observed as dechlorination end product in microcosms containing sediments collected from deeper zones (i.e., 35-40 cm below ground surface). Pyrosequencing of bacterial 16S rRNA genes and 16S rRNA gene-targeted qPCR results revealed Desulfuromonas michiganensis-like populations predominanted in both TCE and cis-DCE producing microcosms. Other abundant groups included Desulfuromonas thiophila and Pelobacter acidigallici-like populations in the surface sediment microcosms, and Desulfovibrio dechloracetivorans and Fusibacter paucivorans-like populations in the deeper sediment microcosms. Dehalococcoides spp. populations were not detected in these sediments before and after incubation with PCE. The results suggest that tidal flats harbor novel, salt-tolerant dechlorinating populations and that titanium pyrosequencing provides more detailed insight into community structure dynamics of the dechlorinating microcosms than conventional 16S rRNA gene sequencing or fingerprinting methods. PMID:21053056

Lee, Jaejin; Lee, Tae Kwon; Löffler, Frank E; Park, Joonhong

2010-10-30

406

Abiotic reductive dechlorination of chlorinated ethylenes by iron-bearing phyllosilicates  

Microsoft Academic Search

Abiotic reductive dechlorination of chlorinated ethylenes (tetrachloroethylene (PCE), trichloroethylene (TCE), cis-dichloroethylene (c-DCE), and vinylchloride (VC)) by iron-bearing phyllosilicates (biotite, vermiculite, and montmorillonite) was characterized to obtain better understanding of the behavior of these contaminants in systems undergoing remediation by natural attenuation and redox manipulation. Batch experiments were conducted to evaluate dechlorination kinetics and some experiments were conducted with addition of

Woojin Lee; Bill Batchelor

2004-01-01

407

A method for the rapid dechlorination of low molecular weight chlorinated hydrocarbons in water  

Microsoft Academic Search

1,1,2-Trichloroethylene (TCE), 1,1-dichloroethylene, cis and trans-1,2-dichloroethylene and tetrachloroethylene (PCE), at concentrations of 20 ppm in aqueous solutions were rapidly hydrodechlorinated to ethane (in a few minutes), on the surface of palladized iron in batch experiments that were performed in closed vials. No intermediate reaction products such as 1,1-dichloroethylene, 1,2-dichloroethylenes and vinyl chloride were detected at concentrations > 1 ppm either

Rosy Muftikian; Quintus Fernando; Nic Korte

1995-01-01

408

Review Of Low-Flow Bladder Pump And High-Volume Air Piston Pump Groundwater Sampling Systems At Sandia National Laboratories, New Mexico  

Microsoft Academic Search

Since 1996, Sandia National Laboratories, New Mexico (SNL\\/NM) has run both a portable high-volume air-piston pump system and a dedicated, low-flow bladder pump system to collect groundwater samples. The groundwater contaminants of concern at SNL\\/NM are nitrate and the volatile organic compounds trichloroethylene (TCE) and tetrachloethene (PCE). Regulatory acceptance is more common for the high-volume air piston pump system, especially

S. S. Collins; G. A. Bailey; T. O. Jackson

2003-01-01

409

Simulation-based process optimization for surfactant-enhanced aquifer remediation at heterogeneous DNAPL-contaminated sites  

Microsoft Academic Search

Widespread use of dense non-aqueous phase liquids (DNAPLs) such as TCE and PCE has resulted in contamination of enormous valuable groundwater resources and become high-priority environmental problems. However, experiences from the past decades have demonstrated that DNAPL-contaminated sites were difficult to investigate and challenging to remediate. In this study, a simulation-based process optimization system was developed through integrating a multidimensional

X. S. Qin; G. H. Huang; A. Chakma; B. Chen; G. M. Zeng

2007-01-01

410

SUBCHRONIC TOXICITY OF TETRACHLOROETHYLENE (PERCHLOROETHYLENE) ADMINISTERED IN THE DRINKING WATER OF RATS  

EPA Science Inventory

The study provides data on the effects of tetrachloroethylene in drinking solutions. The acute oral LD(50) was determined in male and female Charles River rats and found to be 3835 mg/kg for males and 3005 mg/kg for females. Male and female rats received theoretical daily doses o...

411

Subchronic toxicity of tetrachloroethylene (perchloroethylene) administered in the drinking water of rats  

SciTech Connect

This study provides data on the effects of tetrachloroethylene in drinking solutions. The acute oral LD50 in male and female Charles River rats was found to be 3835 mg/kg for males and 3005 mg/kg for females. Male and female rats received theoretical daily doses of 14,400, and 1400 mg tetrachloroethylene/kg body wt/day for 90 consecutive days. There were no compound-related deaths. Body weights were significantly lower in male and female rats at the higher doses. There were no consistent dose-related effects on any of the hematological, clinical chemistry, or urinalysis parameters. 5'-Nucleotidase activity was increased in a dose-dependent manner, suggesting possible hepatotoxicity; however, other serum indicators of hepatic function were unaffected by the treatment. There were no gross pathological effects observed. Liver and kidney body weight ratios, but not brain weight ratios, were elevated at the higher doses. There was no other evidence of compound-related toxicity. These data suggest that exposure of humans to reported levels of tetrachloroethylene in drinking water (approximately 1 microgram/liter) does not constitute a serious health hazard.

Hayes, J.R.; Condie, L.W. Jr.; Borzelleca, J.F.

1986-07-01

412

Analytical Modeling of A By-product Transport in Chain Reactions  

NASA Astrophysics Data System (ADS)

Many chemical reactions of contaminants in the subsurface involve complex reaction pathways and networks. As one of those reaction networks, chain-reactions can be found in radionuclide decay, denitrification, biodegradation of chlorinated solvents, etc. For example, this reaction pattern can be illustrated by the biodegrdation of tetrachloroethylene (PCE) and trichloroethylene (TCE). PCE reacts to produce TCE and TCE reacts to form dichloroethylene (DCE). DCE will further reacts to form vinyl chloride (VC) and finally VC reacts to produce thylene (ETH). During the chain reactions, by-products, such as chloride in PCE reaction chain, can be produced in groundwater. For this reason, by-prodcut concentrations in the contaminant plumes are elevated relatively to ambient concentrations. Because of the neutral chemical behavior of some by-products, they can be treated as indicators to identify the sources of contaminants and to estimate reaction rates. Often, a single by-prodcut is produced from multiple steps in a reaction chain. Then, the partial differential equation for by-product mass balance is coupled by multiple reactants. This makes it difficult, if not impossible, to derive analytical solutions using integral transforms. Instead, we conduct singular value decomposition (SVD) analytically and develop a closed-form solution of a by-product transport in multiple chain reactions. In achieving the analytical solution, all reactions are assumed to be first-order and the system is assumed to be homogeneous and isotropic.

Sun, Y.; Lee, K.; Buscheck, T. A.

2003-12-01

413

DNAPL Extraction/Oleofilter Test Report  

SciTech Connect

A short term, low flow DNAPL extraction test was performed from May 29 - 30, 1997, to gather additional information about the possibility of using monitoring well MSB-3D to recover source contamination from the M-Area Aquifer. Although no visible, free phase material was recovered, the groundwater did contain perchloroethylene (PCE) at and above aqueous solubility. Improvements in the pumping configuration were identified for future trials. Prior to final treatment in the M1 air stripper, the groundwater was passed through an Oleofiltration system to evaluate its capability as a treatment technology. The Oleofilter uses a combination of conventional gravity assisted separation with coalescing plates and a final polishing filter using proprietary coated granules to remove hydrocarbons. Although free phase DNAPL was not processed through the Oleofilter, the groundwater containing high levels of dissolved PCE was treated efficiently. Initially the Oleofilter removed 99 percent of the PCE. As the test progressed, this removal rate decreased to 83 percent as the granules became loaded with PCE. Longer term testing, perhaps with periodic backflushing, is required to determine the effective granule capacity.

White, R.M. [Westinghouse Savannah River Company, AIKEN, SC (United States); Hazel, C.

1997-11-03

414

Investigation of the long-term performance of zero-valent iron for reductive dechlorination of trichloroethylene  

SciTech Connect

This research investigated the long-term performance of zero-valent iron for mediating the reductive dechlorination of trichloroethylene (TCE). Over a 2-year period, rates of TCE dechlorination in columns packed with iron filings were measured in simulated groundwaters containing either 3 mM CaSO{sub 4}, 5 mM CaCl{sub 2}, or 5 mM Ca(NO{sub 3}){sub 2}. At early elapsed times, TCE reaction rates were pseudo-first-order in TCE concentration and were independent of the solution pH. With increasing elapsed time, reaction rates deviated from pseudo-first-order behavior due to reactive site saturation and increased iron surface passivation toward the influent end of each column. The extent of passivation was dependent on both the TCE concentration and the background electrolyte solution. For most of the investigation, TCE reaction rates in 3 mM CaSO{sub 4} and 5 mM CaCl{sub 2} solutions were statistically identical at the 0.05 confidence level. However, TCE reaction rates in 5 mM Ca(NO{sub 3}){sub 2} were slower. In columns operated using chloride- and sulfate-containing waters, the effective half-life for TCE dechlorination increased from approximately 400 min after 10 days elapsed to approximately 2,500 min after 667 days. The effective TCE half-life in the nitrate-containing water increased from approximately 1,500 min after 10 days to approximately 3,500 min after 667 days. Measurements of iron corrosion rates in nitrate and chloride solutions showed that nitrate contributed to increased iron surface passivation and decreased rates of iron corrosion. Corrosion current measurements indicated that halocarbon reduction on fresh iron surfaces was cathodically controlled, whereas on aged iron surfaces, iron corrosion was anodically controlled. Anodic control of iron corrosion contributed to the development of reactive site saturation with time and to similar reaction rates for TCE and perchloroethylene. Passivation of the iron surfaces was found to be dependent on the adhering tendency of the corrosion products and not on the overall mass of corrosion products in the columns. The decrease in TCE reaction rates over time can be attributed to anodic control of iron corrosion and not to increasing reactant mass transfer limitations associated with diffusion through porous corrosion products.

Farrell, J.; Kason, M.; Melitas, N.; Li, T.

2000-02-01

415

Validation and application of pharmacokinetic models for interspecies extrapolations in toxicity-risk assessments of volatile organics. Final report, 1 Jul 87-30 Apr 91  

SciTech Connect

Direct measurements of perchloroethylene (PER), trichloroethylene (TCE), trichloroethane (TRI) and dichloroethylene (DCE) were made in the blood and exhaled breath of rats during and following inhalation exposures. The pharmacokinetics of these four halocarbons were also investigated following oral administration. An accurate assay for measuring volatile halogenated hydrocarbons in a variety of body tissues was developed and demonstrated for PER, TCE, TRI, and tetrachloroethane (TET). The tissue concentration-time profiles and bioavailability for PER and TET were determined in liver, kidney, brain, fat, lung, heart, and muscle tissues following oral and intraarterial administrations in rats. Interspecies comparisons of the pharmacokinetics of PER and TET were made following oral and intraarterial administrations in two species: Sprague-Dawley rats and Beagle dogs. Neurobehavioral determinations were conducted in rats following inhalation exposures, single oral bolus administration, and gastric infusion of PER.

Dallas, C.E.

1991-07-23

416

Isolation and Characterization of a Facultatively Aerobic Bacterium That Reductively Dehalogenates Tetrachloroethene to cis-1,2-Dichloroethene.  

PubMed

A rapidly-growing facultatively aerobic bacterium that transforms tetrachloroethene (PCE) via trichloroethene (TCE) to cis-1,2-dichloroethene (cis-1,2-DCE) at high rates in a defined medium was isolated from a contaminated site. Metabolic characterization, cellular fatty acid analysis, and partial sequence analysis of 16S rRNA showed that the new isolate, strain MS-1, has characteristics matching those of the members of the family Enterobacteriaceae. Strain MS-1 can oxidize about 58 substrates including many carbohydrates, short-chain fatty acids, amino acids, purines, and pyrimidines. It can transform up to 1 mM PCE (aqueous) at a rate of about 0.5 (mu)mol of PCE(middot) h(sup-1)(middot)mg (dry weight) of cell(sup-1). PCE transformation occurs following growth on or with the addition of single carbon sources such as glucose, pyruvate, formate, lactate, or acetate or with complex nutrient sources such as yeast extract or a mixture of amino acids. PCE dehalogenation requires the absence of oxygen, nitrate, and high concentrations of fermentable compounds such as glucose. Enterobacter agglomerans biogroup 5 (ATCC 27993), a known facultative bacterium that is closely related to strain MS-1, also reductively dehalogenated PCE to cis-1,2-DCE. To our knowledge, this is the first report on isolation of a facultative bacterium that can reductively transform PCE to cis-1,2-DCE under defined physiological conditions. Also, this is the first report of the ability of E. agglomerans to dehalogenate PCE. PMID:16535267

Sharma, P K; McCarty, P L

1996-03-01

417

Isolation and Characterization of a Facultatively Aerobic Bacterium That Reductively Dehalogenates Tetrachloroethene to cis-1,2-Dichloroethene  

PubMed Central

A rapidly-growing facultatively aerobic bacterium that transforms tetrachloroethene (PCE) via trichloroethene (TCE) to cis-1,2-dichloroethene (cis-1,2-DCE) at high rates in a defined medium was isolated from a contaminated site. Metabolic characterization, cellular fatty acid analysis, and partial sequence analysis of 16S rRNA showed that the new isolate, strain MS-1, has characteristics matching those of the members of the family Enterobacteriaceae. Strain MS-1 can oxidize about 58 substrates including many carbohydrates, short-chain fatty acids, amino acids, purines, and pyrimidines. It can transform up to 1 mM PCE (aqueous) at a rate of about 0.5 (mu)mol of PCE(middot) h(sup-1)(middot)mg (dry weight) of cell(sup-1). PCE transformation occurs following growth on or with the addition of single carbon sources such as glucose, pyruvate, formate, lactate, or acetate or with complex nutrient sources such as yeast extract or a mixture of amino acids. PCE dehalogenation requires the absence of oxygen, nitrate, and high concentrations of fermentable compounds such as glucose. Enterobacter agglomerans biogroup 5 (ATCC 27993), a known facultative bacterium that is closely related to strain MS-1, also reductively dehalogenated PCE to cis-1,2-DCE. To our knowledge, this is the first report on isolation of a facultative bacterium that can reductively transform PCE to cis-1,2-DCE under defined physiological conditions. Also, this is the first report of the ability of E. agglomerans to dehalogenate PCE.

Sharma, P. K.; McCarty, P. L.

1996-01-01

418

Identification of active dehalorespiring microbial populations in anoxic river sediment by RNA-based stable isotope probing  

NASA Astrophysics Data System (ADS)

Tetrachloroethene (perchloroethylene, PCE), a persistent contaminant in aquifers, soils and sediments, can be reductively dechlorinated by anaerobic microorganisms in a process referred to as dehalorespiration. However, the biodiversity of dehalorespiring microorganisms and their distribution especially in pristine environments is largely unexplored. Therefore, the aim of this study was to detect potentially novel PCE-dehalorespiring microorganisms by using stable isotope probing (SIP), a technique that allows to directly identify the function of uncultivated microbial populations. We simulated a PCE contamination by incubating pristine river sediment in the presence of PCE at a steady, low aqueous concentration (20 ?M). Dehalogenation activity in microcosms (20 nmol cis-dichloroethene per ml slurry per day formed) was detected already after 4 weeks at 20°C with sediment indigenous electron donors. The microbial community in sediment incubations was probed with 13C-labelled acetate (0.5 mM) as electron donor and carbon source at 15°C for 3 days. After RNA extraction, "heavy" 13C-rRNA and light 12C-rRNA were separated by isopycnic centrifugation, and Bacteria-related populations in gradient fractions were characterised by terminal restriction fragment length polymorphism analysis and cloning. In heavy gradient fractions from the microcosm with PCE, we detected a prominent 506-bp terminal restriction fragment (T-RF) and a few minor T-RFs only. In contrast, in the control without PCE, Bacteria-specific rRNA was restricted to light gradient fractions, and the prominent T-RFs found in the PCE-dechlorinating microcosm were of minor importance. Apparently, 13C-acetate was incorporated into bacterial rRNA more effectively in PCE-respiring microcosms. Thus, rRNA-SIP provides strong evidence for the presence of PCE-dehalorespiring, 13C-acetate-utilising populations in river sediment microcosms. Cloning/sequencing analysis identified the prominent members of the heavy gradient fractions as members of the phylum Chloroflexi only distantly related to cultivated dechlorinating Dehalococcides spp.

Kittelmann, S.; Friedrich, M. W.

2005-12-01

419

Direct mass spectrometric studies of the destruction of hazardous wates. 2. Gas-phase photocatalytic oxidation of trichloroethylene over TiO[sub -2]: Products and mechanisms  

SciTech Connect

The gas-phase photocatalytic oxidation of trichloroethylene (TCE) over titanium dioxide was investigated as a potential method for destroying this common pollutant. The results from this study agree with earlier studies in that high levels of destruction of TCE were achieved. Accompanying these high rates of destruction were high quantum yields (approaching unity). However, direct-sampling mass spectrometry and gas-phase Fourier transform infrared (FTIR) spectroscopy revealed that there are significant quantities of byproducts produced [phosgene, dichloroacetyl chloride (DCAC), carbon monoxide, molecular chlorine]. The DCAC has been rationalized on the basis of a chemical reaction mechanism in which the TCE molecules are oxidized in a chain reaction involving Cl atoms. This mechanism appears to be validated by tests with other chlorinated ethylenes (perchloroethylene, dichloroethylenes). Phosgene may arise at least partially from the photocatalytic oxidation of DCAC, and molecular chlorine may result from the recombination of chlorine atoms. The results of this study are discussed relative to aqueous-phase photocatalytic oxidation of TCE where chlorinated intermediates have been observed. 24 refs., 10 figs., 3 tabs.

Nimlos, M.R.; Jacoby, W.A.; Blake, D.M.; Milne, T.A. (National Renewable Energy Lab., Golden, CO (United States))

1993-04-01

420

Comparison of Reductive Dechlorination of Chlorinated Ethylene in Batch and Continuous-Flow Reactor  

NASA Astrophysics Data System (ADS)

A 1.28 L-Batch reactor and continuous-flow stirred tank reactor (CFSTR) fed with formate and trichloriethene (TCE) were operated for 120 days and 72 days, respectively, to study the effect of formate as electron donor on reductive dechlorination of TCE to cis-1,2-dichloroethylene (c-DCE), vinyl chloride (VC), and ethylene (ETH). In batch reactor, injected 60 ?mol TCE was completely degraded in presence of 20% hydrogen gas (H2) in less than 8 days by Evanite culture (300 mg-soluble protein) with ability to completely degrade tetrachloroethene (PCE) and TCE to ETH under anaerobic conditions. To determine the effect of formate as electron donor instead of H2, about 3 or 11 mmol of formate injected into batch-reactor every 15 days was enough to support H2 for dechlorination of c-DCE to VC and ETH. Soluble protein concentration of Evanite culture during the batch test increased from 300 mg to 688 mg for 120 days. In CFSTR test, TCE was fed continuously at 9.9 ppm (75.38 ?mol/L) and the influent formate feed concentration increased stepwise from 1.3 mmol/L to 14.3 mmol/L. Injected TCE was accumulated at HRT 18 days for 13 days, but TCE was completed degraded at HRT 36 days without accumulation during left of experiment period, getting H2 from fermentative hydrogen production of injected formate. Although c-DCE was also accumulated for 23 days after CFSTR operation, it reached steady-state without accumulation in presence of excessive formate. However, since c-DCE in CFSTR was not completely dechlorinated, we will determine the transcriptional level of enzyme involved in reductive dechlorination of TCE, c-DCE, and VC in our future work.

Park, S.; Jonghwan, L.; Hong, U.; Kim, N.; Ahn, H.; Lee, S.; Kim, Y.

2010-12-01

421

Carbon and chlorine isotope fractionation during microbial degradation of tetra- and trichloroethene.  

PubMed

Two-dimensional compound-specific isotope analysis (2D-CSIA), combining stable carbon and chlorine isotopes, holds potential for monitoring of natural attenuation of chlorinated ethenes (CEs) in contaminated soil and groundwater. However, interpretation of 2D-CSIA data sets is challenged by a shortage of experimental Cl isotope enrichment factors. Here, isotope enrichments factors for C and Cl (i.e., ?C and ?Cl) were determined for biodegradation of tetrachloroethene (PCE) and trichloroethene (TCE) using microbial enrichment cultures from a heavily CE-contaminated aquifer. The obtained values were ?C = -5.6 ± 0.7‰ (95% CI) and ?Cl = -2.0 ± 0.5‰ for PCE degradation and ?C = -8.8 ± 0.2‰ and ?Cl = -3.5 ± 0.5‰ for TCE degradation. Combining the values for both ?C and ?Cl yielded mechanism-diagnostic ?Cl/?C ratios of 0.35 ± 0.11 and 0.37 ± 0.11 for the degradation of PCE and TCE, respectively. Application of the obtained ?C and ?Cl values to a previously investigated field site gave similar estimates for the fraction of degraded contaminant as in the previous study, but with a reduced uncertainty in assessment of the natural attenuation. Furthermore, 16S rRNA gene clone library analyses were performed on three samples from the PCE degradation experiments. A species closely related to Desulfitobacterium aromaticivorans UKTL dominated the reductive dechlorination process. This study contributes to the development of 2D-CSIA as a tool for evaluating remediation strategies of CEs at contaminated sites. PMID:23668287

Wiegert, Charline; Mandalakis, Manolis; Knowles, Tim; Polymenakou, Paraskevi N; Aeppli, Christoph; Machá?ková, Ji?ina; Holmstrand, Henry; Evershed, Richard P; Pancost, Richard D; Gustafsson, Orjan

2013-06-04

422

COMPARISON OF DONOR SUBSTRATES FOR BIOLOGICALLY ENHANCED TETRACHLOROETHENE (PCE) DNAPL DISSOLUTION. (R828772)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

423

Infiltration and redistribution of PCE in a system containing spatial wettability variations  

Microsoft Academic Search

Wettability variations can exist in many subsurface environments as a consequence of spatial and temporal variability in aqueous phase chemistry, variations in grain mineralogy, the presence of organic matter, and\\/or interactions of the formation solids and surface active organic contaminants. This presentation describes results of a laboratory and modeling investigation designed to explore and quantify the effect of spatial wettability

D. M. O'Carroll; S. A. Bradford; L. M. Abriola

2001-01-01

424

Risk-based economic decision analysis of remediation options at a PCE-contaminated site.  

PubMed

Remediation methods for contaminated sites cover a wide range of technical solutions with different remedial efficiencies and costs. Additionally, they may vary in their secondary impacts on the environment i.e. the potential impacts generated due to emissions and resource use caused by the remediation activities. More attention is increasingly being given to these secondary environmental impacts when evaluating remediation options. This paper presents a methodology for an integrated economic decision analysis which combines assessments of remediation costs, health risk costs and potential environmental costs. The health risks costs are associated with the residual contamination left at the site and its migration to groundwater used for drinking water. A probabilistic exposure model using first- and second-order reliability methods (FORM/SORM) is used to estimate the contaminant concentrations at a downstream groundwater well. Potential environmental impacts on the local, regional and global scales due to the site remediation activities are evaluated using life cycle assessments (LCA). The potential impacts on health and environment are converted to monetary units using a simplified cost model. A case study based upon the developed methodology is presented in which the following remediation scenarios are analyzed and compared: (a) no action, (b) excavation and off-site treatment of soil, (c) soil vapor extraction and (d) thermally enhanced soil vapor extraction by electrical heating of the soil. Ultimately, the developed methodology facilitates societal cost estimations of remediation scenarios which can be used for internal ranking of the analyzed options. Despite the inherent uncertainties of placing a value on health and environmental impacts, the presented methodology is believed to be valuable in supporting decisions on remedial interventions. PMID:20117877

Lemming, Gitte; Friis-Hansen, Peter; Bjerg, Poul L

2010-02-01

425

A vertical Path Computation Element (PCE) based path provisioning scheme in multilayer optical networks  

Microsoft Academic Search

The explosive growth of Internet traffic has led to a dramatic increase in demand for data transmission capacity, which requires\\u000a high transmission rates beyond the conventional transmission capability. This demand has spurred tremendous research activities\\u000a in new high-speed transmission and switching technologies. As optical transmission technology keeps maturing, next generation\\u000a optical networks are expected to be controlled by Generalized Multiprotocol

Hyuncheol Kim; Jeom Goo Kim