Final Report: Evaluation of Biosparging Performance and Process Fundamentals for Site Remediation

EPA Grant Number: R825549C050
Subproject: this is subproject number 050 , 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: Evaluation of Biosparging Performance and Process Fundamentals for Site Remediation
Investigators: Dupont, R. Ryan , Doucette, William J. , Sorensen, D. L.
Institution: Utah State University
EPA Project Officer: Hahn, Intaek
Project Period: May 1, 1994 through December 1, 1998
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (1989) RFA Text |  Recipients Lists
Research Category: Analysis/Treatment of Contaminated Soil , Land and Waste Management


The goal of this proposed project is to conduct a detailed investigation of air sparging systems operated in a pulsed mode to provide a fundamental framework from which to evaluate the applicability and effectiveness of biosparging technology for a given set of site/soil/waste constraints. To accomplish this goal, the following research questions will be addressed through laboratory and field scale air sparging system analysis:

  • What are the fundamental governing mechanisms affecting gas flow and gas/liquid mixing and transfer within porous media at the field scale?

  • What are the fundamental mechanisms governing the rate and extent of enhanced degradation of contaminants in a saturated zone affected by air sparging?

  • What are the governing characteristics affecting performance of an air sparging system under simulated and actual field conditions?

  • What is the appropriate engineering design approach for air sparging system design and process performance monitoring?

    These questions will be addressed through an integrated program of field and pilot scale studies designed to enhance on-going activities at an existing field site, and to take advantage of field site assessment data and system design investments that have taken place at this site to date.

  • Summary/Accomplishments (Outputs/Outcomes):

    Air sparging represents a highly attractive remediation alternative for contaminants located below the groundwater table as it has been shown through anecdotal evidence that contaminant emission rates increase and groundwater concentrations are greatly reduced at groundwater monitoring well points. The specific mechanisms of air sparging system performance are yet to be investigated, and adequate monitoring of field scale systems to quantitatively document their performance throughout effected areas of injection well influence is yet to be developed. In this project, a detailed evaluation of contaminant and oxygen mass transfer rates, and the interaction of mass transfer and indigenous biological contaminant degradation rates will be investigated at the laboratory and field scales to provide the data that are currently not available regarding fundamental behavior of air sparging systems operated in a biosparging mode. This project will provide the first comprehensive look at fundamental level phenomenon at a laboratory and field scale that will be useful for a more rigorous design and evaluation of new air sparging system installations designed for pulsed operation where contaminant degradation is emphasized over high rate air injection and stripping.

    A laboratory-scale tank simulation of the IWA system was conducted in order to demonstrate the performance of the system in a relatively homogeneous environment and provide a baseline for deviations of the field data from ideal design performance. The system was simulated in 2.5' x 2.5' x 2.5' stainless steel tank filled with uniform, washed, construction sand. The IWA system was simulated using 1/8" tubing with a 1.5" long slotted/screened interval to simulate piezometers and to allow withdrawal of samples. Samples were collected from the tubing using 5-mL syringes. Tracers were sampled from three elevations below the water table and at radii equivalent to equivalent to field grid locations. Samples were also collected from piezometers immediately adjacent to the upper and lower screens of the simulated IWA well. Air was injected into the IWA well at a flow rate of 100 mL/min. The system was operated for 24 hours prior to tracer injection, and background samples were collected for baseline measurements. Fluorescein concentrate (1x108 ppb) was injected into the piezometer immediately adjacent to the lower screen of the simulated IWA well to simulate a field divergent tracer test. Eleven rounds of water samples were collected and analyzed for fluorescein over a 2,460-minute test period.

    Laboratory sorption isotherm experiments were also conducted to estimate the sorption of organic dye tracers to soils collected from the Layton site, in order to predict the impacts of retardation on the tracer studies in both the laboratory and field experiments.

    Monitoring system. The sensors selected for use in the saturated zone included a Technalithics Laboratory DO probe, a SenSym pressure transducer, and a CSI thermocouple. The DO probe and thermocouple performed well in both laboratory and field trials. The SenSym pressure transducer was not adequately temperature compensated and should be replaced in the bundle design. The saturated zone bundle (each manufactured for less than $650) also included a tube for collecting discrete samples from the isolated aquifer regions and a stirring blade to insure that groundwater surrounding the DO probe was moving during data collection. Stirring blades were moved by AC motors located in several of the well heads. The sensor selected to measure oxygen concentration in the vadose zone is manufactured by Figaro. It performed adequately in the laboratory tests and maintained calibration during the field trials. A Figaro HC sensor to monitor vapor phase TPH was evaluated, but output from the sensor was unstable and it was not included in the final bundle.

    A total of 49 monitoring points were installed at the field site over a period of 4 days. Each point was hydraulically driven into the ground to reduce problems with short-circuiting of injected air. Once a procedure was developed for auguring pilot holes and driving the points, it was possible to install at least 15 points per day. As a retrofit, the asphalt, well heads, and some road base were removed and replaced so that a system of buried conduit could be installed for protection of the data acquisition system and wiring that connected all of the monitoring points. The retrofit also provided an area below grade where the datalogger and associated hardware were protected from moisture and forklift traffic. There was no damage to any instrumentation or cables during the IAS and IWA testing over a period of 15 months.

    The instrumentation bundles performed better than expected during field trials in terms of sensor calibration, routine maintenance requirements, and reliability of the data acquisition system. The temperature compensation problems with the pressure transducers were disappointing but could be corrected by replacing the SenSym transducer. Unless a much more expensive, submersible transducer was selected, very little modification to the bundle design would be required.

    Problems due to recharge times in tight soils, recharge from regions with higher conductivity, and pump-induced flow patterns were reduced by minimal purging and low flow collection techniques using the sampling tube in each bundle to provide samples of ground water that were representative of the surrounding aquifer. Statistical analysis of consecutive samples from the same well indicated that variation among replicates was random and that there was no advantage to a larger purge volume. The overall efficiency of the ANOVA model for the grid could be improved by collecting multiple samples from each point and partitioning the error due to variability of consecutive samples out of the experimental error and subsampling error terms.

    One design change required before this type of system is installed at another site is modification of the transmission system for the stirring motor assemblies. In an effort to reduce costs and due to the small diameter of the well heads at the field site, the stirring cables for several wells were attached to each of only six motors. Small radius turns of the speedometer cables, where they attached to gear assemblies at each motor, resulted in binding and snapping. This problem could be solved by using larger well heads for all saturated zone monitoring points and placing a motor in each well head. Another solution would be to include a "u-joint" arrangement at the connection of the cable to the gear assemblies.

    Field study results. The monitoring system allowed for quantitative evaluation of the technologies for remediating the contaminated soil and groundwater as well as revealing more about underlying soil conditions. Due to the low hydraulic conductivity of the soils at the site, neither technology performed effectively at increasing mass transfer of oxygen into the aquifer to stimulate aerobic degradation. There was no reduction in hydrocarbon concentration or in the total dissolved mass of hydrocarbon across the site during the application of either air injection technology at the Layton site. The monitoring system demonstrated its value by providing data to support these conclusions, which would not have been possible without it.

    During operation of both IAS and IWA systems at the site, there was no change in DO, total head, or HC constituent concentration in the outer-most radius of monitoring points. Therefore, these points were available for use as "controls" and the shape of the VOI could be defined with fewer points than might have been necessary in a Cartesian system. Because the layout of the monitoring system and the statistical model were developed together, all parameters measured with the monitoring grid were compared across depth, distance, and direction with the relatively simple statistical model.

    IAS system characterization. The monitoring system may have affected the outcome of IAS tests at the field site to some extent. There was short-circuiting into one of the monitoring points located 3 radial feet from the central IAS well almost immediately when air injection was initiated. A densely spaced, balanced arrangement of monitoring points, encircling the point of injection, provided the information necessary to conclude that the IAS system did not actually have of ROI of 3 ft (91 cm) even though there was evidence of air migration to one location at that radius. Even with the short-circuiting, sensor response indicated that there was a rapid increase in pressure throughout the monitoring grid when the blower was turned on, followed by a steady, more gradual decline. The increase in total head in the monitoring points was greater deeper and closer to the injection well than near the water table or near the outside of monitoring grid. This pressure distribution was as expected and indicates that, while the monitoring system may have been somewhat affecting the flow of air from the injection well by providing a pathway for air migration to the vadose zone, the monitoring system was capable of describing the asymmetry of air flow in the saturated zone.

    Technology transfer related to this project has primarily taken the form of manuscripts for publication in refereed journals and books, presentation and posters at professional meeting, and direct interaction with the site owners through semi-annual written and oral updates and progress reports. Reference to technical and professional output of the project can be found in the list of publications.

    Journal Articles on this Report : 1 Displayed | Download in RIS Format

    Other subproject views: All 13 publications 4 publications in selected types All 1 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 Hall BL, Baldwin CK, Lachmar TE, Dupont RR. Instrumentation design and installation for monitoring air injection ground water remediation technologies. Ground Water Monitoring & Remediation 2000;20(2):46-54. R825549C050 (Final)
  • Abstract: Wiley - Abstract
  • Supplemental Keywords:

    biosparging, biodegradation, oxygen transfer., Scientific Discipline, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Contaminated Sediments, Environmental Chemistry, Geochemistry, Analytical Chemistry, Fate & Transport, Bioremediation, Ecology and Ecosystems, fate and transport, contaminant transport, migration, biosparging, biodegradation, contaminated sediment, adsorption, contaminant biodegradation rates, biotechnology, contaminants in soil, bioremediation of soils, chemical kinetics, heavy metal contamination, phytoremediation, contaminated soils, groundwater

    Relevant Websites: Exit

    Progress and Final Reports:

    Original Abstract
  • 1994
  • 1995
  • 1996
  • 1997

  • 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