Final Report: Chlorinated Solvent Impact and Remediation Strategies for the Dry Cleaning Industry

EPA Grant Number: R828598C766
Subproject: this is subproject number 766 , established and managed by the Center Director under grant R828598
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Gulf Coast HSRC (Lamar)
Center Director: Ho, Tho C.
Title: Chlorinated Solvent Impact and Remediation Strategies for the Dry Cleaning Industry
Investigators: Bedient, Philip B.
Institution: Rice University
EPA Project Officer: Lasat, Mitch
Project Period: September 1, 2000 through August 31, 2004
RFA: Gulf Coast Hazardous Substance Research Center (Lamar University) (1996) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Targeted Research

Objective:

The availability of electron donor to subsurface microbes has been recognized as an important influence on rates of dechlorination, and aquifer hydrogeology is one factor that plays a significant role in insuring efficient delivery. One of the most important concerns is in regard to clogging of aquifer systems through the addition of the constituents necessary to carry out dechlorination and from methane that results from the developing methanogen community. To address these concerns and to achieve the milestones outlined in the original proposal the following objectives have been defined: 1. Determine the effectiveness of Hydrogen Release Compound (HRC) as a hydrogen delivery method for stimulation of reductive dechlorination 2. Evaluate the initial hydrogeologic conditions of the ECRS using tracer tests and “start-up” tests 3. Evaluate the impact of HRC, PCE and microbe injection and the resulting microbial growth on the hydrogeology of the aquifer system, the Experimental Controlled Release System (ECRS) tank equipped with 28 sampling ports, using follow up hydraulic tests 4. Model the ECRS system with MODFLOW to better understand the distribution of hydraulic conductivity 5. Determine spatial variability of dechlorination products 6. Compare hydraulic characteristics with zones of biological activity and determine why dechlorination activity differed between source zone locations 7. Analyze results for statistical significance and help identify what mechanism can be correlated with successful biological growth. The initial steps towards answering the objectives were completed through a tracer test and a transient water level monitoring test. Both of these tests were conducted before HRC, PCE and microbe addition to characterize the velocity and flow pattern. The results from the above tests were used in the development of both steady state and transient MODFLOW models. The input from the first two tests provided observation data for calibration and a check on the calculated hydraulic conductivity. An understanding of the microbial interactions was gained through a series of comprehensive spatial samplings of the ECRS that measured parameters such as methane, COD, pH, etc. Most recently, a statistical analysis was performed to determine which factors were the best predictor of biological performance, i.e. dechlorination.

Summary/Accomplishments (Outputs/Outcomes):

Additional funding has been received from the Advanced Technologies Program of the State of Texas by collaborators on this project, Dr. Herb Ward and Dr. Joseph Hughes. This follow-up study will provide a further in depth analysis of the benefits of bioremediation for the treatment of chlorinated solvents beyond the laboratory-scale, in the Experimental Controlled Release System tanks.

The earlier work that was performed in these pilot-scale tanks has provided us the insight and the background that has led to additional near-field scale studies funded by both GCHSRC and the American Petroleum Institute. This new work is investigating the environmental implications associated with the use of ethanol additive fuels as oxygenates in gasoline.

The findings from our research show that enhanced bioremediation and bioaugmentation may be viable options for decreasing source longevity and potentially overall exposure to chlorinated solvents with shorter plume lengths. This treatment option is also low maintenance and requires minimal equipment when a long-term electron donor such as Hydrogen Release Compound is used in sufficient quantities. Furthermore, our study reassures the public that huge quantities of methane will not be produced nor will there be the need to have the direct injection of hydrogen gas through these techniques and thus preventing potential explosive hazards.

Tracer Test:  The main objective of this research was to study the effectiveness of a hydrogen delivery system that will provide an electron donor for effective stimulation of biological reductive dechlorination of chlorinated solvents. A hydraulic characterization of the system was first step towards reaching this goal and was essential to making informed decisions for later injections of PCE and microbes. Therefore, a tracer test was performed to evaluate the variation in hydraulic conductivity in the Experimental Controlled Release System (ECRS) tank located at Rice University. The test began with the injection of a six hour pulse input of 1000 mg/L bromide solution into the inlet of the ECRS tank. Approximately 400 samples of 50 to 100 mL were taken from 12 sample lines down the 18 ft length of the tank over the 107 hour length of the experiment.  The results indicate that the ECRS tank was not packed evenly, with what appears to be areas of hard pack through the center that retard the mass of bromide flowing through. Despite the heterogeneity, the bromide mass was conserved and some general trends were seen. There was an uneven bromide front, with flow reaching the lines located ~ 2ft from the side walls appearing first, showing that the gravel pack did not fill up before it began leaving the area and the bromide solution didn’t then move as a uniform wave as was predicted. Sampling locations 2 feet off the bottom vertically at any location saw only trace amounts of bromide, on the order of 10 times less than their counterpart 1.5 ft below at the same x,y coordinate, demonstrating that there was almost no vertical mixing. Both of main sets of results lead us to believe that there is very low dispersion through the sand and the ECRS is very similar to field conditions marked with much heterogeneity. 

Tank Preparation:  The tracer test proved to be very beneficial to the entire group and served as the foundation for all further experimental decisions. The understanding of the hydraulic characteristics dictated the placement the of  PCE DNAPL injection into the ECRS tank. PCE was injected through manually syringing approximately 0.33 L into 3 sampling lines, which made up the source zone. Each of these injection points are located 2 feet from the base of the tank and roughly two-thirds down the length of the tank. This location was chosen so that dechlorination products could be seen in the effluent in a relatively short period, 3-5 days, and to allow for sufficient distance upstream for fermentation to occur. Based on bench scale work in the laboratory, this amount was calculated so that pooling of DNAPL on the bottom on the tank would not occur. The PCE was allowed to distribute under recycle flow conditions for two weeks to establish a residual high aqueous concentration of 10 to 30 mg/L. Following the PCE addition anaerobic conditions were established by the addition of acetate. Once the ECRS was made anaerobic, 30 gallons of microbe solution (10 mg/L biomass) was added. Shortly afterwards, lactate was added as an electron donor to help establish the microbe population. Finally, 21 gallons of hydrogen release compound (HRC) was added to act as the electron donor for the remainder of the experiment.

Spatial Samplings:  After the introduction of a mixed anaerobic culture into the ECRS, and the Hydrogen Release Compound (HRC) injection up gradient of the source zone to provide a slow release of electron donor, dechlorination performance was monitored with effluent samples to check for the presence of metabolites (TCE, DCE, VC, ethene).  The successful bioaugmentation and subsequent detectable concentrations of dechlorination products from effluent samples in the ECRS provided a favorable system for the study of the interaction between the microbial communities and the resulting chemical products. Concentration measurements of chlorinated ethenes (PCE, TCE, DCE, VC and ethene), pH, methane, acetate, propionate and chemical oxygen demand (COD) were determined through chemical analysis. The spatial distributions of all the above constituents were evaluated through a series of comprehensive samplings of the ECRS. The chemical analyses of the dechlorination products were performed through GC head space analysis. The results from these analyses were plotted with the Groundwater Modeling System (GMS) for a graphical interpolation of the data.

Tremendous spatial variability between the zones of biological activity and in the distribution of chemical products was observed in ECRS system. The system was initially thought to be geologically homogenous. However, the ECRS system resembled the heterogeneity observed at a typical field site more closely than was anticipated. In some cases, samples from locations only a few feet apart yielded very different results. In the three sampling locations constituting the source zone, PCE and microbes were injected in equal amounts and using the same procedure. However, there existed considerable variation among the resulting chemical constituents and dechlorination activity in the source zone lines residing in the same transect.

Comparisons between the performance at the source zone locations were based on the concentrations of not only the dechlorination products themselves, but also through other biological indicators such as methane and COD. These comparisons provided an additional understanding of what mechanisms were responsible for the processes observed in the source zone. The results of this study found that the variation in electron donor delivery was primarily responsible for the differences observed in the dechlorination performance in the source zone locations. In addition, the methanogens and dechlorinators in the ECRS appeared to have a complementary relationship. Both communities thrived under high COD conditions and there seemed to be adequate electron donor. In samples taken from areas where chlorinated ethenes were present, the production of methane was concurrent with the formation of dechlorination products. These observations imply that while methanogens were competitors with dechlorinating organisms for the hydrogen substrate, the dechlorination process was not impeded by active methanogenesis in the ECRS system. 

Statistical Analysis:  The daily aqueous samples taken from the ECRS effluent to monitor the biological and chemical activity provided a substantial data set that up to this point had only been analyzed through qualitative means of graphical plots. In the reductive dechlorination process, assessing success (PCE going to its final product, ethene) on the field-scale is very difficult and data intensive. Therefore, by understanding which biological processes are correlated, a species or group of species may act an indicator of successful dechlorination. There were a total of 203 observations; however, some were removed from data set because they did not include all of the desired variables. The remaining data was comprised of 147 observations.  This portion of the data was collected exclusively from the effluent; therefore, it is an average of the activity occurring in the ECRS tank.

Five to six predictors (methane, COD, acetate, pH, propionate, plus after some initial tests, the previous day’s dechlorination performance) were used to estimate the current day’s dechlorination performance through various statistical methods. Rather than solely analyzing the concentrations of the dechlorination products to assess the degree of biological activity, the chlorine number was also used as an indicator of performance. The chlorine number composites the chlorinated ethene concentrations and scales them from 0 to 4. At zero, no chlorinated species are present (all ethene or ethane remains); at 4 all of the ethene is in the form of PCE. The optimal outcome is for the chlorine numbers to decrease over time, demonstrating that PCE was being dehalogenated to its daughter products. An advantage of the chlorine number analysis beyond comparing concentrations is that it standardizes the amount of products present regardless of concentrations, by weighing the amount of chlorinated ethenes present. It is not known what exact initial concentrations of PCE were present at each location after injection; however, the chlorine number compensates for this, too. For statistical analyses, the chlorine number acts as a single response variable for how the biological activity is affected by the chemical environment.
 
Previously, r2 correlations had been calculated through Excel. These correlations showed evidence of the relationship of some species; however, it was typically not consistent between sampling events and proved to provide only a limited interpretation. Therefore, this portion of the study has performed a more in-depth statistical analysis. The statistical package Minitab was used for all calculations. With the five to six predictor variables, the first step was to determine which ones would best estimate the response variable, the chlorine number. This selection was done using the Stepwise Regression function, which through repeated testing of hypotheses was able to determine whether an adding or removing a variable improves the statistical significance of the model. Once the significant variables were determined, a simple Linear Regression was performed. Additional transformations on the data were performed to optimize the prediction.

The final result was that the statistical methods of stepwise regression, linear regression and time series autocorrelation, along with a logarithmic transformation on the data set selected the lagged chlorine number variable and methane to be the best predictors of the current chlorine number, the response variable representing the cumulative concentration of the chlorinated ethenes remaining. The other two significant predictors, pH and COD, decrease as the chlorine number decreases. For pH, the increased biological activity represented by dropping chlorine number causes the production of slightly acidic conditions. While for COD, as the dechlorination process proceeds the COD, which is composed of lactate that is transformed to the microbe’s energy source hydrogen, is consumed. This result verified Capiro’s Master of Science research results that methane producing microbes (methanogens) do not impede dechlorination performance within an aquifer system, but instead they are an indictor that the process is occurring (Capiro 2002). Both microbe communities are able to utilize the hydrogen electron donor without severe issues in competition, as shown by the stepwise regression result that as chlorine number decreases and dechlorination occurs, methane increases.

Conclusions:

The findings of this study, based on objectives outlined earlier in this report are discussed in detail below. The conclusions are presented in a temporal progression, with each finding building on the understanding from the previous. The investigations performed through the use of tracer tests, transient water level monitoring, MODFLOW models and spatial analyses of aqueous samples have led to the following conclusions:

  • The hydraulic characterization of the ECRS found important heterogeneities throughout the tank. Most notably a low area of hydraulic conductivity through the center altered the flow field and influenced the travel time of constituents through that area. The variation in hydraulic conductivity ranged from 3.53 x10-3 cm/sec to 3.18 x10-2 cm/sec for the majority of the sand pack.
  • The injection of HRC, PCE and microbes appeared to have minimal impact on the hydraulics of the ERCS system. The comparisons of the transient MODFLOW results from the two start-up tests showed undetectable differences in the hydrogeology; however, localized short-circuiting is still a possibility that should not be overlooked.  Still, the dominant influence on the flow through the tank appeared to be the original packing of the ECRS. 
  • The distribution of dechlorination products varied both horizontally and vertically, while also encompassing a large range of concentrations.
  • Through the experiments that were performed, no direct correlation between hydraulics and the spatial distributions of the chemicals could be made.
  • Methanogens did not appear to impede the performance of dechlorinators. Where there was dechlorination activity there was also methanogenesis occurring and there where no obvious signs that methanogens out competed for the available H2.
  • The methane production by methanogens appeared to cause no detectable amounts of clogging in the ECRS.
  • The poor dechlorination performance in one of the source zone points appears to be attributed a lack of electron donor arriving to that vicinity. COD levels at this line were consistently much lower, and methanogenesis even appears to be hindered in this region.
  • The best source zone dechlorination performance 17 can be correlated to the higher COD concentrations and higher methane concentrations than the other two source zone locations. Further confirming that delivery of electron donor is the key and that methanogens and dechlorinators complement one another, leading to a mutually beneficial environment.
  • The statistical interpretation of the data shows that methane and the previous day’s chlorine number to be the best predictors of the current day’s chlorine number.

Journal Articles:

No journal articles submitted with this report: View all 4 publications for this subproject

Supplemental Keywords:

chlorinated solvents, electron donor competition,, RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Waste, Water, TREATMENT/CONTROL, POLLUTANTS/TOXICS, Contaminated Sediments, Remediation, Environmental Chemistry, Treatment Technologies, Chemicals, Hazardous Waste, Environmental Monitoring, Ecological Risk Assessment, Water Pollutants, Groundwater remediation, Hazardous, Environmental Engineering, fate and transport, hazardous waste management, hazardous waste treatment, degradation, environmental technology, advanced treatment technologies, industrial waste, microbial degradation, in situ remediation, drycleaning industry, cleanup, contaminated sediment, remediation technologies, contaminated soil, TCE degradation, treatment, hazadous waste streams, wet oxidation, contaminated groundwater, groundwater contamination, PCE, technology transfer, chlorinated solvents, TCE, bioremediation, hot water extraction

Progress and Final Reports:

Original Abstract
  • 2001 Progress Report
  • 2002
  • 2003

  • Main Center Abstract and Reports:

    R828598    Gulf Coast HSRC (Lamar)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R822721C529 Environmentally Acceptable Endpoints: Risk Based Remediation Using Bioremediation
    R822721C552 Degradative Solidification/Stabilization Technology for Chlorinated Hydrocarbons
    R822721C569 Treatment and Product Recovery: Supercritical Water Oxidation of Nylon Monomer Manufacturing Waste
    R822721C620 Colloidal Fouling of Membranes: Implications in the Treatment of Textile Dye Wastes and Water Reuse
    R822721C626 Catalytic Hydroprocessing of Chlorinated Organics
    R822721C627 The Interaction of Microbial Activity and Zero Valent Iron Permeable Barrier Technology
    R822721C630 Microbial Cometabolism of Recalcitrant Chemicals in Contaminated Air Streams
    R822721C633 Catalyst Lifetime Studies for Chlorocarbon Steam Reforming
    R822721C635 Electrokinetic/Surfactant-Enhanced Remediation of Hydrophobic Pollutants in Low Permeability Subsurface Environments
    R822721C636 Transformation Reactions of Nitroaromatic and Nitrogen Heterocyclic Compounds on Granular Activated Carbon (GAC) Surfaces: Enhancement of GAC Adsorption in Natural and Engineered Environmental Systems
    R822721C640 Environmentally Friendly Organic Synthesis in Supercritical Fluids
    R822721C645 Development and Evaluation of an Integrated Model to Facilitate Risk-Based Corrective Action at Superfund Sites
    R822721C651 Adjustable Biopolymer Chelators for Cadmium, Lead and Mercury
    R822721C653 New Electrochemically Smart Catalysts for Hazardous Waste Management and Development of Capillary Electrophoresis for Analysis of their Products
    R822721C655 Soil Sampling in South Alabama Oil Fields
    R822721C659 Subsurface Contamination Site Characterization via a Computer-Aided Visual Tool
    R822721C661 New Insoluble supports for Protein Immobilization for Use in Metalloprotein Affinity Metal Chromatography
    R822721C663 Soil Remediation with Ultra-High-Efficiency Hydrocyclones
    R822721C669 Solid Acid Catalyzed Alkylation in Supercritical Fluids
    R822721C679 Regeneration/Reactivation of Carbon Adsorbents by Radio Frequency (RF) Induction Heating
    R822721C687 Improved Halogen Resistance of Catalytic Oxidation
    R822721C696 Phytoremediation and Bioremediation of Land Contaminated By PAHs, PCBs, and TNT
    R822721C697 Fundamental and Kinetic Investigation of Sorbent Technology for Optimum Mercury Emission Control
    R822721C700 Effects of Natural and Cyclic Variations on Contaminant Fate and Transport
    R822721C703 Enhancement of DNAPL Dissolution Rates by Dechlorinating Anaerobes
    R826694C620 Colloidal Fouling of Membranes: Implications in the Treatment of Textile Dye Wastes and Water Reuse
    R826694C625 Enhanced Treatment of DNAPLs Contaminated Soils and Groundwater Using Biosurfactants: In-Situ Bioremediation
    R826694C626 Catalytic Hydroprocessing of Chlorinated Wastes
    R826694C627 The Interaction of Microbial Activity and Zero Valent Iron Permeable Barrier Technology
    R826694C629 Biofiltration of BTEX in Petroleum-Contaminated Soil Remediation Off-Gas
    R826694C630 Microbial Cometabolism of Recalcitrant Chemicals in Contaminated Air Streams
    R826694C633 Catalyst Lifetime Studies for Chlorocarbon Steam Reforming
    R826694C635 Electrokinetic/Surfactant-Enhanced Remediation of Hydrophobic Pollutants in Low Permeability Subsurface Environments
    R826694C636 Transformation Reactions of Nitroaromatic and Nitrogen Heterocyclic Compounds on Granular Activated Carbon (GAC) Surfaces: Enhancement of GAC Adsorption in Natural and Engineered Environmental Systems
    R826694C640 Environmentally Friendly Organic Synthesis in Supercritical Fluids
    R826694C645 Development and Evaluation of an Integrated Model to Facilitate Risk-Based Corrective Action at Superfund Sites
    R826694C651 Adjustable Biopolymer Chelators for Cadmium, Lead, and Mercury Remeidation
    R826694C659 Subsurface Contamination Site characterization Via a Computer-Aided Visual Tool
    R826694C661 New Insoluble supports for Protein Immobilization for Use in Metalloprotein Affinity Metal Chromatography
    R826694C669 Solid Acid Catalyzed Alkylation in Supercritical Reaction Media
    R826694C679 Regeneration and Reactivation of Carbon Adsorbents by Radio Frequency Induction Heating
    R826694C696 Phytoremediation and Bioremediation of Land Contaminated By PAHs, PCBs, and TNT
    R826694C697 Fundamental and Kinetic Investigation of Sorbent Technology for Optimum Mercury Emission Control
    R826694C700 Effects of Natural Cyclic Variations on Contaminated Fate and Transport
    R826694C703 Enhancement of DNAPL Dissolution Rates by Dechlorinating Anaerobes
    R826694C705 A Pilot Plant for Producing Mixed Ketones from Waste Biomass
    R826694C722 The Effects of an Oily-Phase on VOC Emissions from Industrial Wastewater
    R826694C724 Mercury Removal from Stack Gas by Aqueous Scrubbing
    R826694C725 Transport, Fate and Risk Implications of Environmentally Acceptable Endpoint Decisions
    R826694C731 Development and Application of a Real-Time Optical Sensor for Atmospheric Formaldehyde
    R826694C734 An Advanced System for Pollution Prevention in Chemical Complexes
    R828598C001 Field Study Abstract: A Model of Ambient Air Pollution in Southeast Texas Using Artificial Neural Network Technology
    R828598C002 Hollow Fiber Membrane Bioreactors for Treating Water and Air Streams Contaminated with Chlorinated Solvents
    R828598C003 Fugitive Emissions of Hazardous Air Pollutants from On-Site Industrial Sewers
    R828598C004 Biofiltration Technology Development
    R828598C005 A Risk-Based Decision Analysis Approach for Aquifers Contaminated with DNAPLs
    R828598C006 In-Situ Remediation for Contaminated Soils Using Prefabricated Vertical Drains
    R828598C007 Membrane Technology Selection System for the Metal Finishing Industry
    R828598C008 Sequential Environments for Enhanced Bioremediation of Chlorinated Aliphatic Hydrocarbons
    R828598C009 Waste Minimization in the Magnetic Tape Industry: Waterborne Coating Formulations for Magnetic Tape Manufacture
    R828598C010 Soil Remediation by Agglomeration with Petroleum Coke
    R828598C011 Recovery of Dilute Phosphoric Acid in Waste Streams Using Waste Gas Ammonia: The Regenerative MAP/DAP Process
    R828598C012 Stochastic Risk Assessment for Bioremediation
    R828598C013 Selective Removal of Heavy Metals from Wastewater by Chelation in Supercritical Fluids
    R828598C014 Optimization of Treatment Technologies for Detoxification of PCB Contaminated Soils
    R828598C015 Wastewater Remediation by Catalytic Wet Oxidation
    R828598C016 Permanence of Metals Containment in Solidified and Stabilized Wastes
    R828598C017 Combustion Enhancement by Radial Jet Reattachment - Low Generation of Hazardous Gases and High Thermal Efficiency
    R828598C018 A Process To Convert Industrial Biosludge and Paper Fines to Mixed Alcohol Fuels
    R828598C019 Homogeneous Catalysis in Supercritical Carbon Dioxide
    R828598C020 Ultrasonic Enhancement of the Removal of Heavy Metals
    R828598C021 The Binding Chemistry and Leaching Mechanisms of Advanced Solidification/Stabilization Systems for Hazardous Waste Management
    R828598C022 Development of an Air-Stripping and UV/H2O2 Oxidation Integrated Process To Treat a Chloro-Hydrocarbon-Contaminated Ground Water
    R828598C023 A Comparative Study of Siting Opposition in Two Counties
    R828598C024 Sonochemical Treatment of Hazardous Organic Compounds II: Process Optimization and Pathway Studies
    R828598C025 Laser Diagnostics of the Combustion Process within a Rotary Kiln Incinerator
    R828598C026 Use of Inorganic Ion Exchangers for Hazardous Waste Remediation
    R828598C027 Kaolinite Sorbent for the Removal of Heavy Metals from Incinerated Lubricating Oils
    R828598C028 Destruction of Chlorinated Hydrocarbons in Process Streams Using Catalytic Steam Reforming
    R828598C029 Integrated Process Treatment Train (Bioremediation {Aerobic/Anaerobic} and Immobilization) for Texas Soils Contaminated with Combined Hazardous Wastes
    R828598C030 Photo-Oxidation by H2O2/VisUV of Off-Gas Atmospheric Emissions from Industrial and Environmental Remediation Sources
    R828598C031 Concentrated Halide Extraction and Recovery of Lead from Soil
    R828598C032 Biodegradable Surfactant for Underground Chlorinated Solvent Remediation
    R828598C033 A Software Guidance System for Choosing Analytical Subsurface Fate and Transport Models Including a Library of Computer Solutions for the Analytical Models
    R828598C034 Hydrodynamic Modeling of Leachate Recirculating Landfill
    R828598C035 Measurement of Oxygen Transfer Rate in Soil Matrices
    R828598C036 Sorbent Technology for Multipollutant Control During Fluidized Bed Incineration
    R828598C037 Pollution Prevention by Process Modification Using On-Line Optimization
    R828598C038 Pollution Prevention by Process Modification
    R828598C039 Water Solubility and Henry's Law Constant
    R828598C040 Transferring Technical Information on Hazardous Substance Research by Publishing on the World Wide Web
    R828598C041 Stress Protein Responses to Multiple Metal Exposure in Grass Shrimp
    R828598C042 Life-Cycle Environmental Costing for Managing Pollution Prevention in the Chemical and Petroleum Refining Industries: A Cross-Border Approach
    R828598C687 Improved Halogen Resistance of Catalytic Oxidation Through Efficient Catalyst Testing
    R828598C696 Phytoremediation and Bioremediation of Land Contaminated By PAHs, PCBs, and TNT
    R828598C697 Fundamental and Kinetic Investigation of Sorbent Technology for Optimum Mercury Emission Control
    R828598C700 Effects of Natural Cyclic Variations on Contaminated Fate and Transport
    R828598C703 Enhancement of DNAPL Dissolution Rates by Dechlorinating Anaerobes
    R828598C705 A Pilot Plant for Producing Mixed Ketones from Waste Biomass
    R828598C722 The Effects of an Oily-Phase on VOC Emissions from Industrial Wastewater
    R828598C724 Mercury Removal from Stack Gas by Aqueous Scrubbing
    R828598C725 Transport, Fate and Risk Implications of Environmentally Acceptable Endpoint Decisions
    R828598C731 Development and Application of a Real Time Optical Sensor for Atmospheric Formaldehyde
    R828598C734 An Advanced System for Pollution Prevention in Chemical Complexes
    R828598C743 Field Demonstration of Ultrasound Enhancement of Permeable Treatment Walls
    R828598C744 Optical Fibers Coated With Titania Membrane/UV-Generating Crystal in a Distributed-Light Photoreactor for VOC Oxidation
    R828598C749 Characterization and Modeling of Indoor Particulate Contaminants In a Heavily Industrialized Community
    R828598C753 Adsolubilization and Photocatalysis in a Semiconducting Monolithic Reactor for Wastewater Treatment
    R828598C754 Remote Detection of Gas Emissions in Industrial Processes
    R828598C759 Searching for Optimum Composition of Phosphogypsum: Fly ash: Cement Composites for Oyster Culch Materials
    R828598C761 Development of a Phytologically-Based Biosorptive Water Treatment Process
    R828598C766 Chlorinated Solvent Impact and Remediation Strategies for the Dry Cleaning Industry
    R828598C769 Soil/Sediment Remediation by Hot Water Extraction Combined with In-Situ Wet Oxidation
    R828598C771 Fluoracrylate Polymer Supported Ligands as Catalysts for Environmentally Benign Synthesis in Supercritical Fluids
    R828598C774 The Feasibility of Electrophoretic Repair of Impoundment Leaks
    R828598C777 Surfactant Enhanced Photo-oxidation of Wastewaters
    R828598C778 Stationary Power Generation Via Solid Oxide Fuel Cells: A Response to Pollution and Global Warming
    R828598C786 Photocatalytic Recovery of Sulfur and Hydrogen From Hydrogen Sulfide
    R828598C787 Biosurfactant Produced from Used Vegetable Oil for removal of Metals From Wastewaters and Soils
    R828598C789 Genetic Engineering of Enzymatic Cyanide Clearance
    R828598C791 Characterizing the Intrinsic Remediation of MTBE at Field Sites
    R828598C799 Simultaneous Water Conservation/Recycling/Reuse and Waste Reduction in Semiconductor Manufacturing
    R828598C801 Building Defined Mixed Cultures To Biodegrade Diverse Mixtures Of Chlorinated Solvents
    R828598C802 Engineering of Nanocrystal Based Catalytic Materials for Hydroprocessing of Halogenated Organics
    R828598C807 Commercial Demonstration of Hydrogen Peroxide Injection to Control NOx Emissions from Combustion Sources
    R828598C809 Evaluating Source Grouting and ORC for Remediating MTBE Sites
    R828598C810 Application of Total Cost Assessment To Process Design In the Chemical Industry
    R828598C846 Quantitative Demonstration of Source-Zone Bioremediation in A Field-Scale Experimental Controlled Release System