Remediation Technology Task Group
Scholarly Products 1995 -2000
| A framework
for estimating site-specific contaminant release from
soils and wastes Author: Kosson, D.S., Other Author(s): J.Z. Tsao, and A. Garrabrants. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1996 Citation: Society for Risk Analysis (SRA) and International Society for Exposure Assessment (ISEA) Joint Meeting. New Orleans, LA, December 8-11. Abstract: |
| A novel
method to determine biokinetics of anaerobic
dechlorinating bacteria in contaminated site soil
samples. Poster Author: Karvonen, A., Other Author(s): and H. David Stensel. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1998 Citation: CRESP 1998 Annual Meeting, Dingmans Ferry, Pa, June. Abstract: |
| Above ground
bioreactor designs Author: Stensel, H.D. Other Author(s): Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1996 Citation: Short course Hazardous Waste Solvents in Subsurface Environments: Transport, Risks, Remediation. CRESP, Seattle, WA, September 9-11. Abstract: |
| An approach
for estimation of contaminant release during utilization
and disposal of municipal waste combustion residues Author: Kosson, D.S., Other Author(s): H.A. van der Sloot, and T.T. Eighmy. Document Type: CRESP Published Manuscripts Publication Date: 1996 Citation: Journal of Hazardous Materials 47: 43-75. Abstract: The use of appropriate leaching tests and leaching models can help to predict how constituents in municipal waste combustion residues will leach during either utilization or disposal scenarios. This paper presents a general approach for estimating constituent release from MWC residues under a variety of management scenarios through use of fundamental leaching, site specific design and regional climatic parameters. Leaching behavior is categorized as being controlled by either (i) constituent availabiltiy or solubility for percolation-dominated scenarios with loose granula residues, or, (ii) controlled by diffusion for flow around scenarios with compacted granular residues or monolithic products containing residues. Three broad scenarios involving either disposal or utilization are used to illustrate the approach. The scenarios are applied to bottom ash, combined ash and APC residue. In two specific cases pertinent to bottom ash utilization, field data are used to verify the approach. Field data are also used to verify the approach for diposal of combined ash. These methodologies hold promise for serving as a basis for evaluating and comparing potential environmental impacts from different management scenarios for combustion residues and for other waste materials. |
| Applied
microbiology: Anaerobic processes Author: Ferguson, J. Other Author(s): Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1996 Citation: Short course on Hazardous Waste Solvents in Subsurface Environments: Transport, Risks, Remediation. CRESP. Seattle, WA, September 9-11. Abstract: |
| Biodegradation
of btex-contaminated gas in a sparged shallow liquid
reactor Author: Bielefeldt, A.R., Other Author(s): and H.D. Stensel. Document Type: CRESP Proceedings Publication Date: 1997 Citation: In proceedings of the Fourth International In Situ and On-Site Bioremediation Symposium 5: 37-42, New Orleans, LA, April 28- May 5. Abstract: |
| Biodegradation
of chlorinated organic compounds Author: Stensel, H.D., Other Author(s): and A.R. Bielefeldt. Document Type: CRESP Published Books, Chapters, and Sections Publication Date: 1998 Citation: In Bioremediation of Hazardous Wastes; Principles and Practice. New York: Technomic, Inc. Abstract: |
| Biodegradation
of contaminated gas in a sparged shallow liquid reactor Author: Bielefeldt, A.R., Other Author(s): and H.D Stensel. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1997 Citation: InSitu and On-Site Bioremediation, 4th International Symposium. New Orleans, LA, April 21. Abstract: |
| Biodegradation
of VOC emissions in a shallow sparged gas treatment
reactor Author: Bielefeldt, A.R., Other Author(s): and H.D. Stensel. Document Type: CRESP Submitted Manuscripts Publication Date: 200X Citation: Environmental Science and Technology. Abstract: |
| Biological
treatment of carbon tetrachloride in soil vapor
extraction contaminated gases Author: Zou, S., Other Author(s): H.D. Stensel, and J.F. Ferguson. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1998 Citation: DNAPLES: Mobilization and Remediation Techniques of the International Conference on Decommissioning and Decontamination and on Nuclear and Hazardous Waste Management, Denver, CO. September 17. Abstract: |
| Biological
treatment of carbon tetrachloride in soil vapor
extraction contaminated gases Author: Zou, S., Other Author(s): H.D. Stensel, and J.F. Ferguson Document Type: CRESP Proceedings Publication Date: 1998 Citation: In proceedings of Spectrum American Nuclear Society Annual Meeting '98: International Conference on Decommissioning and Decontamination and on Nuclear and Hazardous Waste Management. American Nuclear Society #60526,.LaGrange Park, IL, . 1045-1050 Abstract: |
| Biological
treatment of carbon tetrachloride in soil vapor
extraction contaminated gases. Poster Author: Zou, S., Other Author(s): H. D. Stensel, and J.F. Ferguson. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1998 Citation: CRESP 1998 Annual Meeting, Dingmans Ferry, Pa, June. Abstract: |
| Biological
treatment of VOCs and odor contaminated gases Author: Bielefeldt, D.A., Other Author(s): M. Romaine, and H. D. Stensel. Document Type: CRESP Proceedings Publication Date: 1997 Citation: In proceedings of the Water Environment Federation Annual Conference. Abstract: |
| Carbon
tetrachloride degradation: Effect of microbial growth
substrate and vitamin B12 content Author: Zou, S., Other Author(s): H.D. Stensel, and J.F. Ferguson. Document Type: CRESP Published Manuscripts Publication Date: 200X Citation: Environmental Science and Technology 34 (9): 1751 -1757. Abstract: The microbial degradation kinetics of carbon tetrachloride (CT) under reducing conditions was investigated for different cultures, fed with 1,2-propanediol, dextrose, propionaldehyde, or acetate and nitrate, in the anaerobic step of an anaerobic/aerobic operation sequence. Methanogensis was inhibited due to the aerobic step. CT biodegradation rates followed first-order kinetics with respect to CT concentration and were not affected by the presence of the growth substrate. CT degradation rates increased linearly with higher intracellular vitamin B12 content. The culture fed 1,2-propanediol had the highest vitamin B12 content, which was 3.8, 4.7, and 16 times that of the propionaldehyde-, dextrose-, and acetate-fed cultures, respectively, and its first-order degradation rate constant was 2.8, 4.5, 6.0 times that for those cultures respectively. No CT degradation occurred with culture liquid, suggesting that intracellular factors were responsible for CT degradation. The propanediol culture was able to sustain a constant CT degradation rate for a 20-day test period without substrate addition. Compared to a propanediol-fed culture grown under anaerobic condition only, the propanediol culture grown under the sequential anaerobic/aerobic condition resulted in more biomass growth and a greater CT degradation rate per unit of propanediol fed, although its CT degradation rate per unit of biomass was lower. |
| Carbon
tetrachloride removal from contaminated gases in a
biological reactor Author: Stensel, H.D., Other Author(s): S. Zou, and J.F. Ferguson. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1998 Citation: Spectrum American Nuclear Society Annual Meeting ‘98. Denver, CO, September 15. Abstract: |
| Carbon
tetrachloride removal from contaminated gases in a
biological reactor Author: Stensel, H.D., Other Author(s): S. Zou, and J.F. Ferguson. Document Type: CRESP Proceedings Publication Date: 1998 Citation: In proceedings of Spectra ‘98. Denver, CO, September 15. Abstract: |
| CRESP
understanding of SRS IOU objectives Author: Kosson, D.S., Other Author(s): Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1999 Citation: June. Abstract: |
| Effect of
alternate substrates on biodegradation kinetics of carbon
tetrachloride Author: Zou, S., Other Author(s): H.D. Stensel, and J.F. Ferguson. Document Type: CRESP In Progress Manuscripts Publication Date: 200X Citation: Abstract: |
| Effect of
hydrogen on reductive dechlorination of chlorinated
ethenes Author: Ballapragada, B.S., Other Author(s): H.D. Stensel, J.A. Puhakka, and J.F. Ferguson. Document Type: CRESP Published Manuscripts Publication Date: 1997 Citation: Environmental Science and Technology 31(6): 1728-1734. Abstract: A methanogenic fluidized bed reactor (FBR) fed with lactate and tetrachloroethene (PCE) was operated for 14 months to study the effect of electron donor and PCE loading on chloroethene dechlorination rates. Lactate was fed continu ously at 200 mg/L (2.2 mmol/L), and the influent PCE feed concentration was increased stepwise from 3.5 to 160 mol/L. Vinyl chloride (VC) and ethene accounted for 80% and 20%, respectively, of the PCE dechlorination. Batch tests with various electron donors showed that H2, propionate, and lactate supported dechlorination of PCE, trichloroethene (TCE), cis-dichloroethene (c-DCE), and VC, whereas no dechlorination was observed with acetate or in the absence of an electron donor. Different short-term steady H2 concentrations were obtained by adjusting the FBR influent lactate feed concentration, and the effect of H2 concentra tion on the rate of chloroethene dechlorination was determined. Dechlorination rates for PCE, TCE, c-DCE, and VC showed a Michaelis-Menten relationship with H2 partial pressure. The half-velocity coefficients for H2 utilization by dechlorinators ranged from 12 to 28 ppm for the chloroethenes and are at least an order of magnitude lower than values reported for methanogens. This implies that dechlorinating bacteria can out-compete methanogens for H2 utilization at low H2 concentration. |
| Effect of
synthetic and natural chelating agents on the microbial
reduction of amorphous fe (|||). Poster Author: Hacherl, E., Other Author(s): and D. Kosson, Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1998 Citation: CRESP 1998 Annual Meeting, Dingmans Ferry, Pa, June. Abstract: |
| Effects of
transient groundwater seepage on transport and
degradation of contaminants in surface water sediments Author: Fox, D., Other Author(s): J. Massmann, and T. Poulsen. Document Type: CRESP Submitted Manuscripts Publication Date: 200X Citation: Water Resources Research. Abstract: |
| Enhancements
for passive vapor extraction: The Hanford study Author: Ellerd M.G., Other Author(s): J.W. Massmann, D.P. Schwaegler, and V.J. Rohay. Document Type: CRESP Published Manuscripts Publication Date: 1999 Citation: Groundwater 37(3): 1-11. Abstract: Passive vapor extraction involves wells that are screened in the unsaturated zone and open to the atmosphere. Gas "I flow out of the subsurface through the open well during periods of low barometric pressure. Field and modeling studies have been completed to evaluate enhancements for a passive apor extraction system at a site contaminated with carbon tetrachloride on the Hanford nuclear reservation near Richland, Washington. During a 38-hour period of low barometric pressure, approximately 500 M3 of air were vented from the subsurface. Approximately 27 grams of carbon tetrachloride were removed from the subsurface during this same outflow event. On an annual basis, more than 15 kilograms of carbon tetrachloride have been removed from each of several passive extraction wells. Computer simulations based on the field data indicate that surface covers smaller than 30 in radius wfll result in relatively small enhancements of flow. However, with larger surface seals (i.e., up to 90 in radius), volumetric flow rates more than doubled. Simulations showed that check valves might increase the rate at which subsurface gases are extracted by a factor of nearly three. These estimates are sensitive to dispersion coefficients. If not properly designed, filters used to treat effluent gases from passive extraction svstems can significantly reduce the effectiveness of these systems. |
| EOHSI/CRESP
Savannah River Site study: Radiation safety global
procedures manual Author: CRESP, Other Author(s): Radiation Safety Committee. Document Type: CRESP Reports Publication Date: 200X Citation: Abstract: |
| Evaluating
source locations for carbon tetrachloride contamination
using vapor rebound curves Author: Riley, G., Other Author(s): and J. Massmann. Document Type: CRESP Submitted Manuscripts Publication Date: 200X Citation: Abstract: |
| Evaluating
source locations for carbon tetrachloride contamination
using vapor rebound curves Author: Riley, G. Other Author(s): Document Type: CRESP Dissertations or Theses in Progress Publication Date: 200X Citation: Abstract: |
| Evaluating
source locations for carbon tetrachloride contamination
using vapor rebound curves Author: Riley, G., Other Author(s): and J. Massmann. Document Type: CRESP In Progress Manuscripts Publication Date: 200X Citation: Abstract: |
| Evaluation of
contaminant release mechanisms for soils and
solidified/stabilized wastes Author: Garrabrants, A.C., Other Author(s): F. Sanchez, T.T. Kosson, J. Mehu, and D.S. Kosson. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1997 Citation: International Conference for the Environmental and Technical Implications of Construction with Alternative materials (WASCON 1997). Netherlands. Abstract: |
| Extraction
technologies Author: Massmann, J. Other Author(s): Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1996 Citation: Short course on Hazardous Waste Solvents in Subsurface Environments: Transport, Risks, Remediation. CRESP, Seattle, WA, September 9-11. Abstract: |
| Including
uncertainty in the design of a vapor extraction and gas
treatment system Author: Stensel, H.D., Other Author(s): M. Hrachovec, and J.W. Massmann. Document Type: CRESP Submitted Manuscripts Publication Date: 200X Citation: ASCE. Abstract: |
| Integrating
risk, restoration and future use of the Savannah River
Site (SRS) Author: Kosson, D.S., Other Author(s): and J. Nelson. Document Type: CRESP Symposia, Workshops, and Stakeholder Events Publication Date: 1997 Citation: Workshop jointly sponsored by Department of Energy, Savannah River Site, Consortium for Risk Evaluation with Stakeholder Participation, Savannah River Ecology Laboratory Conference Center at SRS, September 10-11. Abstract: |
| Leaching and
release of organic contaminants from soils Author: Kosson, D.S., Other Author(s): S. Schaefer, and I. Massry. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1997 Citation: International Conference for the Environmental and Technical Implications of Construction with Alternative Materials (WASCON 1997). Netherlands. June. Abstract: |
| Methodology
for estimating inorganic contaminant release from
untreated and treated soils Author: Garrabrants, A., Other Author(s): T.T. Kosson, and D.S. Kosson. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1996 Citation: Emerging Technologies in Hazardous Waste Management VIII, ACSI&EC Symposium. September. Abstract: |
| Modeling
atmospherically induced subsurface gas flow: The Hanford
passive vapor extraction study Author: Massmann, J.W., Other Author(s): M.G. Ellerd, D.P. Schwaegler, and V.J. Rohay. Document Type: CRESP In Press Manuscripts Publication Date: 200X Citation: Groundwater. Abstract: |
| Modeling of
micropore diffusion as a component of volatile organic
contaminant transport in unsaturated soils with
connective vapor flow Author: Massry, I.W., Other Author(s): and D.S. Kosson. Document Type: CRESP In Progress Manuscripts Publication Date: 200X Citation: Environmental Science and Technology. Abstract: The hypothesis tested here is that desorption phenomena is caused by diffusion controlled release from a distribution of micropore regimes. A multi-aggregate regime (MAR) model incorporating hindered diffusion was developed. The hypothesis was tested by evaluating model predictions for trichloroethylene (TCE) vapor extraction (VE) experimental data (17) obtained over a range of equilibration periods, initial VOC concentrations, vapor flow rates, and water contents. The MAR model was visually fit to a single VE data set, and then used to independently predict all other VE data sets. The model provided excellent predictions for all VE data sets (17). The NMR model estimated that 70% of the sorption sites are in 8 Å pores, 20% in 14.5 Å pores, and 10% in local equilibrium. |
| Modeling of
micropore diffusion as a component of volatile organic
contaminant transport in unsaturated soils with
convective vapor flow Author: Massry, I.W., Other Author(s): and D.S. Kosson. Document Type: CRESP Submitted Manuscripts Publication Date: 200X Citation: ES&T. Abstract: |
| Modeling the
effects of aging on leaching of aromatic hydrocarbons for
saturated soils Author: Rixey, W., Other Author(s): I.W. Massry, G. Sanjay, and D.S. Kosson. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1997 Citation: ACS National Meeting. Las Vegas, NV, September. Abstract: |
| Predicting
the effect of moisture on vapor-phase absorption of
volatile organic compounds to soils Author: Unger, D.R., Other Author(s): T.T. Lam, C.E. Schaefer, and D.S. Kosson. Document Type: CRESP Published Manuscripts Publication Date: 1996 Citation: Environmental Science and Technology 30(4): 1081-1091. Abstract: Sorption from the vapor phase is an important factor controlling the transport of volatile organic compounds (VOCS) in the unsaturated zone. Accurate description of sorption from the vapor phase to soil in the unsaturated zone therefore is intrinsic to predicting the ultimate fate of contaminants. Vapor-phase sorption of several VOCs onto seven soils at oven-dried, air-dried, typical field moisture and water-saturated conditions was measured using a batch-equilibrium headspace method. An equilibrium partitioning model was developed to predict the effect of soil moisture content on vapor-phase sorption.The model was based on the soil pore-size distribution and BET isotherm sorption parameters under oven-dried and water-saturated conditions. The model was shown to accurately predict observed experimental results. |
| Prediction
and experimental validation of liquid-phase diffusion
resistance in unsaturated oils Author: Schaefer, C.E., Other Author(s): R.R. Arands, H.A. van der Sloot, and D.S. Kosson. Document Type: CRESP Published Manuscripts Publication Date: 1995 Citation: Journal of Contaminant Hydrology 20: 145-166. Abstract: Determination of liquid-phase diffusion through unsaturated soils is important for estimating contaminant transport in soils and design of remediation processes for contaminated soils and groundwater. Liquid-phase diffusion through unsaturated soils is governed by both the pore size distribution and water distribution of the soil matrix. Diffusion tube experiments were carried out using several soils packed to field densities to determine the effective diffusivity of chlorideion as a function of soil moisture content. Chloride was selected to serve as a non-volatile, non-sorbing tracer species. A transport model was developed to predict liquid-phase tortuosity as a function of readily obtained soil parameters, including density, moisture content, particle size distribution and pore size distribution. The basis of the model was parallel diffusion resistances in the inter- and intra-particle pore regimes. The new model was found to provide an accurate prediction of observed experimental results. Previously reported models did not agree with experimental results over significant portions of the experimental domain investigated. |
| Remediation
of solvents in subsurface environments Author: Ferguson, J.F., Other Author(s): and H.D. Stensel. Document Type: CRESP Symposia, Workshops, and Stakeholder Events Publication Date: 1996 Citation: University of Washington, Seattle, WA, September 10-11. Abstract: |
| Risk
communication: Addressing public concerns about risk
controversies Author: Kosson, D.S. Other Author(s): Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1997 Citation: Toxicology in Risk Assessment Symposium . U.S. Army Chemical and Biological Defense Command. Bethesda, MD, May 14-16. Abstract: |
| Soil gas
movement Author: Scanlon, B.R., Other Author(s): J.P. Nicot, and J. Massmann. Document Type: CRESP In Press Books, Chapters, and Sections Publication Date: 200X Citation: In Handbook for Soil Science edited by M.E. Sumner. Boca Raton: CRC Press. Abstract: |
| Sorption of
cesium-137 in Savannah River Sites. Poster Author: Arands, R., Other Author(s): N. Thakur, R. Comans, A. de Koning, and D. Kosson. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1998 Citation: CRESP 1998 Annual Meeting, Dingmans Ferry, Pa, June. Abstract: Activities and improper waste disposal related to the production of nuclear materials at the DOE's Savannah River Site have resulted in significant contamination at the site and surrounding area. Cesium-137 is one of the most abundant contamination since it is a common by-product from nuclear soils, its ubiquitous presence at SRS suggests that it is more mobile than expected. This work is focused upon quantifying the sorption mechanisms of [137]Cs and to being integrating these findings into the risk estimation efforts at CRESP. It was found that (i) [137]Cs is relatively mobile at SRS and (ii) the conventional sorption mechanisms for [137]Cs do not completely account for its behavior in SRS soils. Additional work is in progress to identify the additional mechanism(s) of [137]Cs sorption and to integrate these results into the risk estimation process. |
| Sparged
reactor for treatment of contaminated gases Author: Stensel, H. D, Other Author(s): and M. Hrachovec. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1996 Citation: Spectrum American Nuclear Society Annual Meeting '96. Seattle, WA, August 19-22. Abstract: |
| Sparged
reactor for treatment of contaminated gases Author: Stensel, H.D., Other Author(s): and M. Hrachovec. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1997 Citation: 4th International Symposium on In Situ and On-Site Bioremediation. New Orleans, LA, April 28-May 1. Abstract: |
| Sustained
degradation of trichloroethylene in a suspended growth
gas treatment reactor by an actinomycetes enrichment Author: Lee, S.B., Other Author(s): S.E. Strand, and H.D. Stensel Document Type: CRESP Submitted Manuscripts Publication Date: 200X Citation: Environmental Science and Technology Abstract: A laboratory scale suspended-growth gas treatment bioreactor was used to study the sustained degradation of TCE-contaminated gas by a phenol-fed actinomycetes enrichment under aerobic conditions for 160 days at reactor TCE loadings from 27 to 72 mg/L-d and 6-day solids retention time. The presence of TCE with phenol provided a selective pressure favoring the actinomycetes enrichment over another TCE-degrading filamentous enrichment used to seed the reactor. The actinomycetes TCE transformation capacity in a batch test was 1.0 mg TCE/mg VSS and the reactor transformation quantity (Tq) was 0.59 mg TCE/mg VSS wasted. A relatively low applied phenol to TCE ratio at 2.3 g/g was possible in the reactor operation due to high Tq. Michaelis-Menten kinetic parameters for the actinomycetes enrichment were kTCE=0.15 d-1 and Ks,TCE=0.14 mg/L for TCE and kp=10.2 d-1 and Ks,p-0.34 mg/L for phenol. Phenol concentrations above 15 mg/L inhibited phenol degradation. Competitive inhibition between the growth substrate, phenol and TCE was not observed. A metabolite of phenol degradation through catechol, 2-hydroxymuconic semialdehyde, caused a slight transient inhibition of TCE degradation. The actinomycetes culture degraded cis-DCE. |
| The impact of
mass transfer rate limitations, including pore diffusion
and heterogeneity, on groundwater remediation strategies Author: Massry, I.W., Other Author(s): and D.S. Kosson. Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1998 Citation: SRS-CAB meeting, February 23. Abstract: |
| The impact of
mass transfer rate limitations, including pore diffusion
and heterogeneity, on soil vapor extraction remediation
strategies. Poster Author: Massry, I., Other Author(s): D. Berler, D. Kosson Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1998 Citation: CRESP 1998 Annual Meeting, Dingmans Ferry, Pa, June. Abstract: |
| The impact of
micropore diffusion on contaminant transport and
biodegradation rates in soils and aquifer materials Author: Massry, I.W. Other Author(s): Document Type: CRESP Dissertations or Theses Completed Publication Date: 1997 Citation: Rutgers, the State University of New Jersey. Abstract: Field contamination with volatile organic chemicals (VOCs) can be a result of accidental surface spills, leakage from underground storage tanks, or waste disposal. Commonly VOC contaminants are carcinogenic and partially miscible, making them chemicals of concern that can transport through the vadose zone to the groundwater. Modeling contaminant fate in the subsurface can improve design of existing remediation technologies such as vapor extraction and bioremediation, which have been developed and applied to field scale clean-up with varying success. The hypothesis tested here is that desorption phenomena is caused by diffusion controlled release from a distribution of pore regimes. This hypothesis was tested by evaluating model predictions for experimental data obtained over a range of soil types, equilibration periods, initial VOC concentrations, soil moisture contents, fluid phase velocities, and contaminant species. The model predictions were consistent with the hypothesis that micropores (<20 A) in soils resulted in hindered diffusion rates. A multi-aggregate regime transport model was transformed to develop criteria when local equilibrium can be assumed. When the Pe(intra) < 1 local equilibrium is a valid assumption. Sorption of benzene and toluene to different bacterial strains was investigated to study the impact on bioavailability. Results from this study indicate that the sorptive capacities of bacterial strains can differ greatly. Furthermore, alculations based on the toluene partitioning coefficients to bacterial cells determined in this study indicate that sorption to bacteria can contribute considerably to sorption of toluene in soils when cell densities of approximately 10^9 cells/g soil are attained. The frequently observed decrease in contaminant bioavailability with increasing contaminant-soil contact intervals was hypothesized to be a result of hindered diffusion inside a distribution of micropores that are not accessible to bacterial cells due to size exclusion. A transport model based on diffusion within soil micropores and convection and diffusion in inter-aggregate pore spaces with non-linear physical and biological processes was developed and used to evaluate the impact of these factors on biodegradation rates. If soils containing micropores are contaminated with chemicals that can penetrate these pores, then the efficacy of in-situ bioremediation will be limited by diffusion controlled contaminant release from the micropores. |
| The influence
of molecular scale interactions on tce transport
processes in Savannah River soils. Poster Author: Arands R., Other Author(s): B. Teppen, I. Massry, D. Berler, and D. Kosson Document Type: CRESP Presentations, Posters, and Abstracts Publication Date: 1998 Citation: CRESP 1998 Annual Meeting, Dingmans Ferry, Pa, June. Abstract: Activities and improper waste disposal from the production activities at the DOE's Savannah River Site have resulted in significant contamination at the site and surrounding area. Chlorinated solvents were used frequently, and were improperly disposed on-site. Extensive areas have been affected by contamination, such as the TCE, contamination plume in C-Area. This work is focused upon examining the atomic-scale interactions of TCF, with common soil constituents found at SRS (e.g., organic matter or specific clay minerals),. Sorption and diffussion are being examined at the atomic scale using Insight II molecular modeling software from Molecular Simluations, Inc. As new insights into these processes are learned, the results will be incorporated into larger scale transport models (see poster by Massry et al., CRFSP-EOHSI). This is a new initiative updated results from this effort will be presented at the CRFSP Annual Meeting, June 28 - July 1. |
| Treatment of
contaminated gases in a sparged suspended growth
bioreactor Author: Bielefeldt, A.R., Other Author(s): M. Hrachovec, and H.D. Stensel. Document Type: CRESP Submitted Manuscripts Publication Date: 200X Citation: Bioremediation Journal. Abstract: |
| Uncertainties
in cleanup times for soil vapor extraction Author: Massmann, J.W., Other Author(s): S. Shock, and L. Johannesen. Document Type: CRESP In Press Manuscripts Publication Date: 200X Citation: Water Resources Research. Abstract: |