Final Report: Extension of Laboratory Validated Treatment and Remediation Technologies to Field Problems in Aquifer Soil and Water Contamination by Organic Waste Chemicals

EPA Grant Number: R825549C063
Subproject: this is subproject number 063 , established and managed by the Center Director under grant R825549
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: HSRC (1989) - Great Plains/Rocky Mountain HSRC
Center Director: Erickson, Larry E.
Title: Extension of Laboratory Validated Treatment and Remediation Technologies to Field Problems in Aquifer Soil and Water Contamination by Organic Waste Chemicals
Investigators: Illangasekare, Tissa , Bielefeldt, Angela
Institution: University of Colorado at Boulder , Colorado School of Mines
EPA Project Officer: Hahn, Intaek
Project Period: May 19, 1995 through October 2, 2000
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (1989) RFA Text |  Recipients Lists
Research Category: Organic Chemical Contamination of Soil/Water , Land and Waste Management

Objective:

Remediation of aquifers contaminated with organic chemicals is a topic of public concern as well as of considerable scientific, engineering and regulatory interest. Of particular concern are chemicals and waste products in the form of nonaqueous phase liquids (NAPL). Industrial solvents and sludges, electroplating bath solutions and sludges, petroleum refinery wastes, pesticides, wood preservation wastes, corrosive wastes, ignitable solvents, and paint thinners are some of the wastes which are found in the EPA Region pair which fall into this class of chemicals. NAPLs are often identified with contamination resulting from leaking underground storage tanks and pipelines. The class of NAPLs which are denser than water (e.g. creosote, TCA, TCE, PCB etc.)released into the environment are posing challenging and difficult problems due to their complex behavior in naturally heterogeneous subsurface systems. After a spill, they are difficult to detect, characterize and remediate. If located and recovered, still a significant amounts of these chemicals remain entrapped in soil pores at residual saturations and at higher saturations at the interfaces of heterogeneous formations. If left untreated, the persistence of the NAPL hinders cleanup and provides a long term source of contamination into the groundwater through leaching of the more soluble components. In spill and waste sites where the excavation of soil for disposal or treatment becomes infeasible due to physical and economic constraints, in situ treatment schemes such as pump and treat, surfactant washing, air stripping and bioremediation provide attractive alternatives. In recent years, significant work has been done in the basic research on bioremediation, physical and chemically enhanced mobilization, chemical oxidation, soil washing and soil venting. These technologies have been developed and tested in small scale experiments in the laboratory under idealized conditions. Field implementation of these techniques have had limited success due to a number of factors which we have identified in our own ongoing research as well as by other investigators. These factors include, complexities created by the natural soil heterogeneities in the field, chemicals which are in complex mixtures, complex physical, chemical and biological interactions which changes the pore characteristics, dissolution processes that are not very well understood, non-availability of efficient and cost effective field characterization techniques, limitations in the modeling tools which are needed in the design and evaluation of the field remediation techniques, among others. The primary goal of this proposed research is to develop and implement systematic procedures for implementation of treatment and remediation technologies that have been developed in the laboratories to the field, taking into consideration the complexities which are encountered in the field. An extension of the ongoing experimental and modeling efforts are proposed, giving a primary emphasis to field implementation, practical problem solution and technology transfer.

Summary/Accomplishments (Outputs/Outcomes):

Current research efforts by the investigator and co-workers included extensive laboratory investigations in small soil cells, columns, small sand tanks and large soil flumes to obtain a fundamental understanding of the basic processes involved in the transport and entrapment behavior of nonaqueous phase organic chemicals. Issues related to transport, entrapment, recovery, dissolution, fingering and, physical chemical and thermal mobilization have been investigated. Laboratory and modeling studies primarily focused on behavior of these chemicals under heterogeneous aquifer conditions. Effectiveness of various remediation technologies have been investigated in the laboratory scale. Efficient laboratory characterization techniques have been developed. Based on this research, we have arrived at conclusions which have very important implications on research directions that are to be taken with respect to developing viable and effective field methodologies for cleanup and remediation. In addition, related research by investigators funded by the Department of Army and DOE are investigating theoretical and modeling issues associated with up-scaling of flow and transport processes in groundwater systems from the laboratory to field scales. The hypothesis and the rational we have developed in this proposed research are guided by the experience and the knowledge we have developed in these ongoing research efforts.

A systematic procedure to extend the knowledge gained through experimentation at the laboratory scales of pore (micro), cell (micro and macro), column (macro), and soil flumes (pilot) to the field will be developed. Laboratory, modeling and field investigations will focus on issues related to transport, entrapment, recovery, dissolution, fingering and, physical chemical and thermal mobilization, blob dispersion to increase dissolution, etc.that are of fundamental importance in developing remediation technologies. Laboratory experiments in cells, columns and large tanks will be continued to identify the basic parameters which need to be up-scaled to field problems. Some of the parameter we have identified for study include: hydraulic conductivity, capillary pressure vs. saturation, relative permeability, entry pressure, pore size distribution, dispersivity, sorption coefficient, mass transfer coefficients, dissolution parameters, etc. Additional parameters that need to be scaled will be identified as a part of this effort. Careful experiments will be designed both in the lab and in the field. We will use chemical mixtures to look at multicomponent mass transfer and realistic field soils. Sites in Kansas, Colorado, Wyoming and Louisiana will be selected for the field studies. Once the effective parameters are identified, techniques will be developed to obtain these in the field. We will research tracer techniques, improved pumping and slug tests, point sampling strategies and geophysical techniques which are used in other disciplines (e.g. petroleum industry). Our research on model investigations suggest that simulation of exact transport behavior of multiphase fluids in field sites is not feasible. However, using stochastic methodologies (e.g. Monte Carlo Methods) it may be possible to predict probable contaminant zone boundaries and entrapment zones. We will use the multi-phase flow models we have developed and that have been validated using the laboratory data. We will adopt existing three-dimensional models of groundwater flow (e.g. USGS MODFLOW) and solute transport (MT3D) to simulate dissolution and subsequent solute plume migration. For multiphase flow and big-processes we will use models developed at Los Alamos National Laboratory.

The primary accomplishment of this research was the development of methods to up-scale information and knowledge from laboratory to field to address problems involving organic chemicals that are in the form of nonaqueous phase liquids (NAPLs). Issues related to the behavior of both lighter-than water (LNAPLs) petroleum hydrocarbons and waste products found at refinery sites as well as denser-than water (DNAPL) organic solvents found at manufacturing and industrial waste sites were studied. A process that is fundamental to the behavior of NAPLs that contributes to groundwater contamination is the dissolution of the entrapped NAPLs. Understanding and modeling of mass transfer processes taking into consideration the field heterogeneity that creates complex entrapment configurations and multi-dimensional flow fields within the NAPL entrapment zone become critical in up-scaling treatment technologies to the field. Mass transfer processes associated with natural dissolution, enhanced dissolution using surfactants and coupled thermal and surfactant enhanced dissolution were studied in detail. This research demonstrated that the effective implementation of remediation technologies requires the characterization of field heterogeneity as well as determination of the distribution of the NAPLs at spill sites. The study also focused on the development and evaluation of methods to characterize the NAPL entrapment zone. As intrusive techniques such as soil coring do not provide information on the continuous spatial distribution of entrapped NAPL saturation, the viability of the use of multiple tracers as a field characterization technique was investigated. As a part of the characterization investigation, the effects of biodegradation of JP-8 jet fuel and de-icing compounds on the flow and transport characteristics were studied.

During the five-year duration of the project, this grant supported thirteen graduate research assistants and three part-time post-doctoral research associates. The funds were used to complete four Ph.D. dissertations, five MS theses and one MS report. Continuous funding received by the PIs from the Center helped to build a nationally and internationally recognized program in NAPL research in Colorado. The Center funding also allowed the PI to generate additional support from NSF, EPA, Army, Air Force and industry to continue NAPL related research at the University of Colorado and currently at the Colorado School of Mines.

A summary of the key research accomplishments is provided here.

Site-characterization using conservative tracers:

Entrapment of NAPLs changes the hydraulic conductivity field due to changes in relative permeability. In this task, we demonstrated how conservative tracers could be used to estimate the effective flow and transport parameters of the modified flow field. The methods developed will help in designing tracer studies in heterogeneous aquifers. We have demonstrated that it is necessary to consider the aquifer heterogeneity in designing tracer methods both with respect to the complex NAPL entrapment and the movement of tracer plume.

The research findings and tools developed in this research will be used in future collaborations with other researchers conducting field investigations. We will attempt to implement the tracer methods in two field project funded by industry.

Partitioning tracers

This research allowed us to gain a fundamental understanding of the efficacy of partitioning, interfacial, and conservative tracer use in settings where nonaqueous phase liquids (NAPLs) are distributed in complex configurations (e.g. macro-scale entrapment, fingers and pools). Previous researchers attempted to address the simplistic cases of NAPL at residual saturation, but not for situations involving higher-than-residual saturation or occurrences that display some degree of spatial heterogeneity. Considering that the majority of contaminant mass for most NAPL accumulations is within the high-saturation source zones, such as DNAPL pools, it seems appropriate to evaluate the usefulness of multiple tracer techniques for detecting and characterizing these more complex occurrences as well as those at residual saturation.

In order to scale-up the observed influence of spatial variability and NAPL entrapment configuration to actual field settings (an overriding objective of this research), the above goals were assessed in controlled experiments at size scales ranging from laboratory columns to intermediate-scale soil tanks. Results of this work will serve to improve the environmental community's ability to detect and characterize subsurface zones where NAPL contamination is complexly distributed, such as within heterogeneous, layered aquifers.

Natural and Enhanced Dissolution

Understanding and accurate modeling of mass transfer from entrapped sources is of critical importance in the evaluation and prediction of the feasibility and effectiveness of various aquifer remediation strategies. A common assumption that is used in modeling dissolution is that the mass transfer rates are determined by a local equilibrium rate (commonly referred to as Local Equilibrium Assumption or LEA). Using experimental results from tests conducted in large soil tanks, we have shown that the LEA does not model the dissolution rates accurately in complex subsurface systems. The accurate way to model dissolution is to recognize that the mass transfer is rate limited and hence affected by the groundwater flow field. We have demonstrated the critical importance of incorporating the heterogeneity and the flow dimensionality in models that predict mass transfer from entrapped NAPL sources. New prediction models that take into account the flow dimensionality and up-scalable dissolution lengths were developed to simulate both natural and surfactant enhanced dissolution. Using these models, a NAPL dissolution model based on the popular USGS groundwater flow simulator MODFLOW and transport simulator MT3D was developed. With these modeling tools in conjunction with the characterization methods developed in our research, it will be possible to design and evaluate schemes where the process of mass transfer plays a central role (e.g. big-treatment, surfactant enhanced dissolution, big-stabilization).

Hot-surfactant enhanced dissolution

The overall goal of this research task was to investigate an in-situ treatment process that combines surfactants and thermal energy to enhance solubilization and mobilization of entrapped chemical wastes in the subsurface. The specific focus is on lighter than water petroleum waste products (LNAPLs) contained in the smear zone of fluctuating water table, but the treatment process is also potentially applicable to denser than water organic solvents (DNAPLs) in shallow aquifers. Even though it has been demonstrated that surfactant/co-solvent technologies have the potential to remove large amounts of NAPLs in relatively short times in high to moderately permeable formations, their general applicability has been limited due to bypassing of treating agents and mass transfer limitations. Staying within the primary objectives of the research to investigate up-scaling of NAPL remediation technologies, experiments were conducted at varying test scales from small soil columns to intermediate scale soil tanks. Preliminary proof-of-concept experiments that were conducted in intermediate-scale test tanks showed that heat can be used to improve the delivery of surfactants to NAPL entrapment zones, increase the mass transfer and enhance mobilization. Buoyancy forces of heated surfactants introduced below the contaminated zone in combination with reduction in surface tension, increase in solubility and decrease in viscosity associated with increased temperature are used to improve the sweep and recovery efficiencies of entrapped NAPLs. The preliminary findings of this research allowed us to develop a proposal to the Department of Defense under the SERDEP program to test this remediation scheme at a field site.

Up-scaling of JP-8 and deicer biodegradation

The objective of this task was to understand the effects of bio-processes on the fate and transport behavior of de-icing compounds and JP-8 constituents near the ground surface. The particular scenario selected for study was of interest to the U.S. Air Force in determining the fate of jet fuel and aircraft de-icing fluids that are spilled on the runways and released into the environment. When bacteria naturally present in the soil degrade these contaminants, subsequent growth on the bacteria can impact the hydrodynamic properties of the soil and aquifer materials. Laboratory tests in 1-dimensional columns were conducted to study and quantify the effect of biofilm growth on the flow and transport properties of test soils. These studies incorporated different chemical compounds (decane and naphthalene to represent JP-8 and propylene glycol representing de-lcers), contaminant loading rates, sand sizes, flow rates, and varying nutrient levels. Attempts were made to understand the transient nature of biogrowth, since releases of deicing chemicals are intermittent. In addition to characterizing one-dimensional effects, the experiments were scaled up to two-dimensions in which a homogenous, well-characterized porous media contains a defined zone of biogrowth. The behavior of tracers in this system was used to model the effect of biological growth in the porous media at the larger scale. The ability of a model based on 1-D parameters to predict behavior in the 2-D system will provide information on the effectiveness of the model to predict behavior at a larger 3-D field scale.

Field investigations

Two separate research projects were funded to extend the Center funded research to field sites. The first project funded by Union Pacific Railroad involves investigating the end-point saturations of degraded diesel fuel at a site in Oregon. Up-scaling studies are underway in laboratory soils columns and intermediate-scale test tanks. In the second phase of this project the feasibility of different remediation schemes will be investigated using pilot-scale testing.
The second project funded by Chevron involves the use of surfactant to mobilize refinery waste at a site in Cincinnati. Contaminated soil samples from the field site were received and column dissolution studies were completed. Pilot scale studies on up-scaling will involve the use of a 32 ft. long intermediate-scale tank.
As these projects were not funded by the Center, the research results are not reported here. However, it is necessary to highlight the fact that both these projects are extensions of the basic research that was funded by the Center.

Numerous lectures and workshops have been conducted to share the results of this research with consultants, regulators, and other researchers. The principal investigator has conducted EPA-sponsored workshops, prepared chapters for two different books, and given several lectures about this research project. The principal investigator has also engaged in collaborative research with other universities in the U.S. and Europe. Several pier-reviewed articles have been published in journals.


Journal Articles on this Report : 16 Displayed | Download in RIS Format

Other subproject views: All 54 publications 18 publications in selected types All 16 journal articles
Other center views: All 904 publications 230 publications in selected types All 182 journal articles
Type Citation Sub Project Document Sources
Journal Article Barth GR, Illangasekare TH, Hill MC, Rajaram H. A new tracer-density criterion for heterogeneous porous media. Water Resources Research 2001;37(1):21-31. R825549C063 (Final)
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  • Journal Article Barth GR, Hill MC, Illangasekare TH, Rajaram H. Predictive modeling of flow and transport in a two-dimensional intermediate-scale, heterogeneous porous media. Water Resources Research 2001;37(10):2503-2512. R825549C063 (Final)
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  • Journal Article Barth GR, Illangasekare TH, Rajaram H. The effect of entrapped nonaqueous phase liquids on tracer transport in heterogeneous porous media: laboratory experiments at the intermediate scale. Journal of Contaminant Hydrology 2003;67(1-4):247-268. R825549C063 (Final)
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  • Journal Article Bielefeldt AR, Illangasekare TH, Uttecht M, LaPlante R. Biodegradation of propylene glycol and associated hydrodynamic effects in sand. Water Research 2002;36(7):1707-1714. R825549C063 (Final)
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  • Journal Article Bielefeldt AR, McEachern C, Illangasekare T. Hydrodynamic changes in sand due to biogrowth on naphthalene and decane. Journal of Environmental Engineering 2002;128(1):51-59. R825549C063 (Final)
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  • Journal Article Dai DP, Barranco Jr. FT, Illangasekare TH. Partitioning and interfacial tracers for differentiating NAPL entrapment configuration: column-scale investigation. Environmental Science & Technology 2001;35(24):4894-4899. R825549C063 (Final)
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  • Journal Article Held RJ, Illangasekare TH. Fingering of dense nonaqueous phase liquids in porous media. 1. Experimental investigation. Water Resources Research 1995;31(5):1213-1222. R825549C063 (Final)
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  • Journal Article Held RJ, Illangasekare TH. Fingering of dense nonaqueous phase liquids in porous media. 2. Analysis and classification. Water Resources Research 1995;31(5):1223-1231. R825549C063 (Final)
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  • Journal Article Illangasekare TH, Armbruster III. EJ, Yates DN. Non-aqueous-phase fluids in heterogeneous aquifers—Experimental study. Journal of Environmental Engineering 1995;121(8):571-579. R825549C063 (Final)
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  • Journal Article Illangasekare TH, Ramsey Jr. JL, Jensen KH, Butts MB. Experimental study of movement and distribution of dense organic contaminants in heterogeneous aquifers. Journal of Contaminant Hydrology 1995;20(1-2):1-25. R825549C063 (Final)
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  • Journal Article Kuiper LK, Illangasekare TH. Numerical simulation of NAPL flow in the subsurface. Computational Geosciences 1998;2(3):171-189. R825549C063 (Final)
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  • Journal Article Ruan H, Illangasekare TH. Estimation of relative hydraulic conductivity of sandy soils based on a sheet flow model. Journal of Hydrology 1999;219(1-2):83-93. R825549C063 (Final)
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  • Journal Article Saba T, Illangaekare TH. Effect of groundwater flow dimensionality on mass transfer from entrapped nonaqueous phase liquid contaminants. Water Resources Research 2000;36(4):971-979. R825549C063 (Final)
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  • Journal Article Saba T, Illangasekare TH, Ewing J. Investigation of surfactant-enhanced dissolution of entrapped nonaqueous phase liquid chemicals in a two-dimensional groundwater flow field. Journal of Contaminant Hydrology 2001;51(1-2):63-82. R825549C063 (Final)
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  • Journal Article Walser GS, Illangasekare TH, Corey AT. Retention of liquid contaminants in layered soils. Journal of Contaminant Hydrology 1999;39(1-2):91-108. R825549C063 (Final)
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  • Journal Article Wildenschild D, Jensen KH, Hollenbeck KJ, Illangasekare TH, Znidarcic D, Sonnenborg T, Butts MB. A two-stage procedure for determining unsaturated hydraulic characteristics using a syringe pump and outflow observations. Soil Science Society of America Journal 1997;61(2):347-359. R825549C063 (Final)
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  • Supplemental Keywords:

    aquifers, organic chemicals, nonaqueous-phase liquids, remediation., Scientific Discipline, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Environmental Chemistry, Geochemistry, Contaminated Sediments, Remediation, Analytical Chemistry, Fate & Transport, Ecology and Ecosystems, fate and transport, contaminant transport, NAPL, contaminated sediment, biodegradation, chemical transport, chemical contaminants, hazardous waste, hazardous organic substances, bioremediation of soils, chemical kinetics, organic soil contaminants, deicer runoff, groundwater contamination, contaminated groundwater, sorption experiments, jet fuel

    Relevant Websites:

    http://www.engg.ksu.edu/HSRC Exit

    Progress and Final Reports:

    Original Abstract
  • 1995
  • 1996
  • 1997
  • 1998
  • 1999

  • Main Center Abstract and Reports:

    R825549    HSRC (1989) - Great Plains/Rocky Mountain HSRC

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R825549C006 Fate of Trichloroethylene (TCE) in Plant/Soil Systems
    R825549C007 Experimental Study of Stabilization/Solidification of Hazardous Wastes
    R825549C008 Modeling Dissolved Oxygen, Nitrate and Pesticide Contamination in the Subsurface Environment
    R825549C009 Vadose Zone Decontamination by Air Venting
    R825549C010 Thermochemical Treatment of Hazardous Wastes
    R825549C011 Development, Characterization and Evaluation of Adsorbent Regeneration Processes for Treament of Hazardous Waste
    R825549C012 Computer Method to Estimate Safe Level Water Quality Concentrations for Organic Chemicals
    R825549C013 Removal of Nitrogenous Pesticides from Rural Well-Water Supplies by Enzymatic Ozonation Process
    R825549C014 The Characterization and Treatment of Hazardous Materials from Metal/Mineral Processing Wastes
    R825549C015 Adsorption of Hazardous Substances onto Soil Constituents
    R825549C016 Reclamation of Metal and Mining Contaminated Superfund Sites using Sewage Sludge/Fly Ash Amendment
    R825549C017 Metal Recovery and Reuse Using an Integrated Vermiculite Ion Exchange - Acid Recovery System
    R825549C018 Removal of Heavy Metals from Hazardous Wastes by Protein Complexation for their Ultimate Recovery and Reuse
    R825549C019 Development of In-situ Biodegradation Technology
    R825549C020 Migration and Biodegradation of Pentachlorophenol in Soil Environment
    R825549C021 Deep-Rooted Poplar Trees as an Innovative Treatment Technology for Pesticide and Toxic Organics Removal from Soil and Groundwater
    R825549C022 In-situ Soil and Aquifer Decontaminaiton using Hydrogen Peroxide and Fenton's Reagent
    R825549C023 Simulation of Three-Dimensional Transport of Hazardous Chemicals in Heterogeneous Soil Cores Using X-ray Computed Tomography
    R825549C024 The Response of Natural Groundwater Bacteria to Groundwater Contamination by Gasoline in a Karst Region
    R825549C025 An Electrochemical Method for Acid Mine Drainage Remediation and Metals Recovery
    R825549C026 Sulfide Size and Morphology Identificaiton for Remediation of Acid Producing Mine Wastes
    R825549C027 Heavy Metals Removal from Dilute Aqueous Solutions using Biopolymers
    R825549C028 Neutron Activation Analysis for Heavy Metal Contaminants in the Environment
    R825549C029 Reducing Heavy Metal Availability to Perennial Grasses and Row-Crops Grown on Contaminated Soils and Mine Spoils
    R825549C030 Alachlor and Atrazine Losses from Runoff and Erosion in the Blue River Basin
    R825549C031 Biodetoxification of Mixed Solid and Hazardous Wastes by Staged Anaerobic Fermentation Conducted at Separate Redox and pH Environments
    R825549C032 Time Dependent Movement of Dioxin and Related Compounds in Soil
    R825549C033 Impact of Soil Microflora on Revegetation Efforts in Southeast Kansas
    R825549C034 Modeling the use of Plants in Remediation of Soil and Groundwater Contaminated by Hazardous Organic Substances
    R825549C035 Development of Electrochemical Processes for Improved Treatment of Lead Wastes
    R825549C036 Innovative Treatment and Bank Stabilization of Metals-Contaminated Soils and Tailings along Whitewood Creek, South Dakota
    R825549C037 Formation and Transformation of Pesticide Degradation Products Under Various Electron Acceptor Conditions
    R825549C038 The Effect of Redox Conditions on Transformations of Carbon Tetrachloride
    R825549C039 Remediation of Soil Contaminated with an Organic Phase
    R825549C040 Intelligent Process Design and Control for the Minimization of Waste Production and Treatment of Hazardous Waste
    R825549C041 Heavy Metals Removal from Contaminated Water Solutions
    R825549C042 Metals Soil Pollution and Vegetative Remediation
    R825549C043 Fate and Transport of Munitions Residues in Contaminated Soil
    R825549C044 The Role of Metallic Iron in the Biotransformation of Chlorinated Xenobiotics
    R825549C045 Use of Vegetation to Enhance Bioremediation of Surface Soils Contaminated with Pesticide Wastes
    R825549C046 Fate and Transport of Heavy Metals and Radionuclides in Soil: The Impacts of Vegetation
    R825549C047 Vegetative Interceptor Zones for Containment of Heavy Metal Pollutants
    R825549C048 Acid-Producing Metalliferous Waste Reclamation by Material Reprocessing and Vegetative Stabilization
    R825549C049 Laboratory and Field Evaluation of Upward Mobilization and Photodegradation of Polychlorinated Dibenzo-P-Dioxins and Furans in Soil
    R825549C050 Evaluation of Biosparging Performance and Process Fundamentals for Site Remediation
    R825549C051 Field Scale Bioremediation: Relationship of Parent Compound Disappearance to Humification, Mineralization, Leaching, Volatilization of Transformaiton Intermediates
    R825549C052 Chelating Extraction of Heavy Metals from Contaminated Soils
    R825549C053 Application of Anaerobic and Multiple-Electron-Acceptor Bioremediation to Chlorinated Aliphatic Subsurface Contamination
    R825549C054 Application of PGNAA Remote Sensing Methods to Real-Time, Non-Intrusive Determination of Contaminant Profiles in Soils
    R825549C055 Design and Development of an Innovative Industrial Scale Process to Economically Treat Waste Zinc Residues
    R825549C056 Remediation of Soils Contaminated with Wood-Treatment Chemicals (PCP and Creosote)
    R825549C057 Effects of Surfactants on the Bioavailability and Biodegradation of Contaminants in Soils
    R825549C058 Contaminant Binding to the Humin Fraction of Soil Organic Matter
    R825549C059 Identifying Ground-Water Threats from Improperly Abandoned Boreholes
    R825549C060 Uptake of BTEX Compounds by Hybrid Poplar Trees in Hazardous Waste Remediation
    R825549C061 Biofilm Barriers for Waste Containment
    R825549C062 Plant Assisted Remediation of Soil and Groundwater Contaminated by Hazardous Organic Substances: Experimental and Modeling Studies
    R825549C063 Extension of Laboratory Validated Treatment and Remediation Technologies to Field Problems in Aquifer Soil and Water Contamination by Organic Waste Chemicals