Final Report: Laboratory and Field Evaluation of Upward Mobilization and Photodegradation of Polychlorinated Dibenzo-P-Dioxins and Furans in Soil

EPA Grant Number: R825549C049
Subproject: this is subproject number 049 , 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: Laboratory and Field Evaluation of Upward Mobilization and Photodegradation of Polychlorinated Dibenzo-P-Dioxins and Furans in Soil
Investigators: Kapila, Shubhender , Armstrong, Daniel W. , Forciniti, D.
Institution: Missouri University of Science and Technology
EPA Project Officer: Hahn, Intaek
Project Period: July 1, 1992 through April 1, 1996
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


The overall objective of this research is to evaluate the effectiveness of solvent-mediated mobilization and photodegradation of chlorinated dioxins and furans as a means of soil decontamination. In order to meet this objective, a series of laboratory and field experiments have been conducted.

Summary/Accomplishments (Outputs/Outcomes):

Many sites in the United States and abroad have become contaminated with polychlorinated dibenzodioxins and related polychlorinated aromatics, either as a result of accident or industrial activities. The only proven technology for decontaminating the soil at such sites is high-temperature incineration, which is extremely expensive. Destruction of dioxins and furans by natural or artificial sunlight is known to occur and has been shown to be highly efficient under certain conditions in the laboratory. This process, photodegradation, has not been regarded as promising for decontamination of soil, however, due to the sharp attenuation of light beyond a fraction of a millimeter in soil. If the substances to be photodegraded could be brought to the soil surface, the efficiency of the process could be dramatically improved and might provide an option less expensive than incineration.

Experiments were be conducted to study the following: (1) partition behavior of hepta and octachloro dibenzo-p-dioxins in soil and solvent systems which are environmentally acceptable and amenable to photodegradation. Emphasis will be placed on use of complexing agents such as sulfoxides; (2) effects of co-contaminants on dechlorination mechanisms of polychlorinated dibenzo-p-dioxins (PCDDs); (3) photodegradation rate of chlorinated dioxins and furans in suitable solvent systems; (4) quenching effect of co-contaminants on photodegradation; and (5) optimization of carbon adsorption/regeneration for recycling of solvents. Field trials evaluated the efficacy of an optimized mobilization-photodegradation process on a pilot scale at contaminated sites in California and Missouri.

The overall goal of the project was to develop an integrated technique for removal and destruction of polychlorinated dibenzo-p-dioxins (PCDDs) and associated contaminants from soil. The project incorporated laboratory experiments to develop and optimize the technique. The effectiveness of the technique was evaluated through field trials at a contaminated wood treatment site. The site was chosen due to the complexity of contamination, which permitted very rigorous evaluation of the technology.

5.1 Laboratory Experiments
5.1.1 Partition Experiments

These experiments were carried out to study distribution of dioxins in soils (Times Beach, MO, and Visalia, CA) and selected solvent systems. Selection of solvents was based in part on results obtained by Overcash and co-workers, which showed that binary solvent systems consisting of alkanes and alcohol are most proficient for mobilization and photodegradation of dioxins.

5.1.2 Solution Phase Photodegradation Experiments

The goal of these experiments was to optimize irradiation conditions for maximum photodegradation of PCP and tetra through octachloro dioxins. Experiments were carried out under natural and simulated sunlight conditions with and without photocatalyst. The phototransformation rates were highest in the presence of a combination of heterogeneous (titanium oxide) and homogeneous (hydrogen peroxide) photocatalysts. The quantum yield of phototransformation of 2,3,7,8 TCDD and OCDD were found to be >50 fold higher in systems containing TiO2 and H2O2.

5.1.3 Photolvsis of Polychlorinated Dibenzo-p-Dioxins (PCDD) in Vapors and Aerosols

The goal of these experiments was to monitor degradation of PCDDs, which might escape into the atmosphere. Air samples taken at the treatment site revealed no measurable release of PCDDs, however monitoring of the process is still relevant for future development since vapor phase phototransformation is one of the most overlooked areas in the dioxin chemistry research, even though vapor phase extraction, is emerging as a promising soil decontamination technology for semi-volatile organic contaminants such as PAHs.
The irradiation experiments revealed that different dioxin congeners degrade at different rates. The data revealed an inverse relationship between the degree of chlorination and the rate of disappearance. The data also shows that the trichloro congener degraded at a faster rate than the tetrachloro which, in turn, degraded faster than the pentachloro congeners. Significant differences were observed in degradation of constituted congeners. These differences are important in determining toxicity of the congeners. The data indicated that the more toxic laterally substituted congeners degrade at a slower rate than the peri substituted congeners in the condensed phase; this in contrast to degradation observed in the solution phase.

5.2 Field Experiments

The objective of the field trials at Visalia, California, was to demonstrate the applicability of the technique at a heavily contaminated site. Field experiments were conducted in two phases. Phase I experiments were carried out with 8 stainless-steel treatment bins 0.29 m3 while 1.2 m3 treatment bins were utilized in Phase II experiments. The results showed that treatment was effective in reducing the contaminant levels by approximately 90-99%. The primary focus of research during the last seven months of the project was on photocatalyst induced chemical dehalogenation and oxidative degradation during regeneration of activated carbon. These processes should facilitate the recycling of solvents used for removal of contaminants from soil.

5.2.1 Chemical Dehalogenation

Studies in this area have resulted in development of an innovative chemical dehalogenation process designated "CDP." The process utilizes a solid reagent packed in a column. Chlorinated contaminants in solvents or other fluids are effectively destroyed by dehalogenation reactions in the column. The process has proven to be highly efficient and cost effective for removing PCBs from transformer oils and heat exchange oils. The process can be employed on-line and thus permits easy reuse of decontaminated fluids.

The chemical reagent consists of a non-alkali metal, a polyalkyleneglycol. This reagent overcomes the safety- and reaction rate-related problems of the alkali metal or alkali metal oxide polyethylene glycol-based reagents.

The efficiency of the CDP process has been evaluated with the contaminated liquid or solid matrices. The halogenated organic concentration in the matrices ranged from 10-300,000 ppm. In one such evaluation, dehalogenation efficiencies were monitored with a hydrocarbon-based transformer oil containing approximately 700 ppm of PCBs. The concentration of PCBs in the oil was reduced to 2 ppm in just 20 minutes. Process efficiency can be significantly enhanced with the use of ultrasound (frequency 1 Mhz, intensity 12.5 Wcm-2). In reaction augmented with ultrasound agitation, the concentration of PCBs in transformer oil was reduced from 8765 ppm to 24 ppm in approximately 15 minutes.

These results clearly demonstrate that the CDP process is a highly efficient and cost efficient dehalogenation process which utilizes relatively safe reagents and thus should facilitate the recycling of solvents after solvent washing.

5.2.2 Counterflow Oxidative Regeneration (COR)

Photodegradation and chemical dehalogenation processes are efficient in degrading organic chemicals. However, use of the processes over long periods can lead to build-up of residual contaminants and reaction by-products. To maintain high extraction efficiency, these byproducts and constituents resulting from solvent degradation must be removed. This removal can be achieved through adsorption.

A number of adsorbents can be used for such purposes. One of the most effective adsorbents for aromatic compounds is granular activated carbon (GAC). Its application, however, is hampered by high regeneration and/or disposal costs. A process termed Counterflow Oxidative Regeneration (COR) has been developed in our laboratory to alleviate these problems.

The process gets its name from its mode of operation. The spent GAC in a column is regenerated by initiating a flame front at the exit-end of a column. The flame front propagates counter to the direction of oxident flow. The flame temperature exceeds 1500?, ensuring complete destruction of adsorbed organics. Unlike other GAC regeneration processes, COR is a single-step reactivation destruction process that does not require secondary treatment or external input of energy. The flame is sustained by adsorbed contaminants and surface carbon, leaving the bulk (?90%) of the carbon mass intact. The surface area and adsorptive capacity of adsorbent have been found to remain intact after repeated regeneration cycles.

In every case, the destruction of PCBs was practically complete. No PCB residues were detected in the off gases or on the treated carbon. Furthermore, despite an exhaustive analysis, no PCDDs or PCDFs were found above 1 ppb. The results are quite impressive considering that, except for initial ignition, no external source of energy is used during the operation.

The field demonstration of the Technology and the cooperation with Southern California Edison has facilitated technology transfer. In addition to formal publications and presentations, results have been communicated in response to requests from interested professionals.

Journal Articles on this Report : 7 Displayed | Download in RIS Format

Other subproject views: All 17 publications 7 publications in selected types All 7 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 Liu MH, Kapila S, Nam KS, Elseewi AA. Tandem supercritical fluid extraction and liquid chromatography system for determination of chlorinated phenols in solid matrices. Journal of Chromatography A 1993;639(2):151-157. R825549C011 (Final)
R825549C049 (Final)
  • Full-text: ScienceDirect-Full Text PDF
  • Abstract: ScienceDirect-Abstract
  • Journal Article Sivils LD, Kapila S, Yan Q, Elseewi AA. Application of a two-dimensional chromatography system for gas-phase photodegradation studies of polyehlorinated dibenzo-p-dioxins. Journal of Chromatography A 1994;688(1-2):221-230. R825549C049 (Final)
    not available
    Journal Article Sivils LD, Kapila S, Yan Q. Photodegradation of polychlorinated dibenzo-p-dioxins (PCDDs) in vapors and aerosols. Organohalogen Compounds 1995;24:368-373. R825549C049 (Final)
    not available
    Journal Article Tilio R, Krishnan K, Kapila S, Nam KS, Faeehetti S. A simple analytical methodology for multiresidue pollutant determinations. Chemosphere 1994;29(9-11):1849-1858. R825549C049 (Final)
    not available
    Journal Article Tilio R, Kapila S, Nam KS, Bossi R, Facchetti S. Reduction elimination of sulfur interferene in organochlorine residue determination by supercritical fluid extraction. Journal of Chromatography A 1994;662(1):191-197. R825549C049 (Final)
    not available
    Journal Article Yan Q, Sivilis LD, Puri RK, Elseewi AA, Palepu SD, Yanders AF. Effects of co-contaminants on photodegradation kinetics of octachlorodibenzo-p-dioxin (OCDD). Chemosphere 1994;29(9-11):2183-2192. R825549C049 (Final)
    not available
    Journal Article Yan Q, Kapila S, Sivils LD, Elseewi AA. Effects of sensitizers and inhibitors on phototransformation of polychlorinated dibenzo-p-dioxins (PCDDs). Chemosphere 1995;31(7):3627-3634. R825549C049 (Final)
    not available

    Supplemental Keywords:

    photodegradation, mobilization, polychlorinated dibenzo-p-dioxins, furans, soil., RFA, Scientific Discipline, Water, Waste, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Contaminated Sediments, Remediation, Environmental Chemistry, Geochemistry, Fate & Transport, Hazardous Waste, Ecology and Ecosystems, Hazardous, EPA Region, fate and transport, sediment treatment, dioxin, contaminant transport, fate and transport , soil and groundwater remediation, pesticides, contaminated sediment, contaminated soil, furans, groundwater remediation, Region 7, bioremediation of soils, Region 8, chemical kinetics, contaminated groundwater, pesticide runoff, hazardous wate, pesticide residue, heavy metal contamination, phytoremediation, groundwater

    Relevant Websites: Exit

    Progress and Final Reports:

    Original Abstract
  • 1993
  • 1994
  • 1995

  • 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