2004 Progress Report: Development and Evaluation of Field Sensors for Monitoring Anaerobic Dehalogenation after Bioaugmentation for In Situ Treatment of PCE and TCE

EPA Grant Number: R828772C011
Subproject: this is subproject number 011 , established and managed by the Center Director under grant R828772
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: HSRC (2001) - Western Region Hazardous Substance Research Center for Developing In-Situ Processes for VOC Remediation in Groundwater and Soils
Center Director: Semprini, Lewis
Title: Development and Evaluation of Field Sensors for Monitoring Anaerobic Dehalogenation after Bioaugmentation for In Situ Treatment of PCE and TCE
Investigators: Ingle, James D.
Institution: Oregon State University
EPA Project Officer: Lasat, Mitch
Project Period: September 1, 2001 through August 31, 2006
Project Period Covered by this Report: September 1, 2003 through August 31, 2004
RFA: Hazardous Substance Research Centers - HSRC (2001) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management

Objective:

The purpose of this study is to develop, refine, and use sensors and field instruments, based on redox indicators and other reagents as on-site, on-line, or in-situ monitoring tools for assessing and optimizing redox and related conditions for treatment of PCE and TCE with dehalogenating cultures. These sensors and field instruments will be calibrated for evaluating redox conditions and the effectiveness of dechlorination in two collaborative situations involving a bioaugmentation approach in soil columns and physical aquifer models (PAMs).

Progress Summary:

Rationale

Better field and portable monitoring techniques for redox status and related conditions for bioremediation are needed for: (1) the evaluation of laboratory samples, models such as columns and PAMs, and subsurface conditions at a site, (2) continued assessment of the progress of remediation, and (3) examination of the effects of bioaugmentation in field and laboratory experiments. We have demonstrated that redox sensors based on redox indicators exhibit promise for monitoring environmental redox levels. Research is needed to: (1) identify and compare the response of these indicators during bioaugmentation, (2) improve the monitoring devices and methodology (flow cells, fiber optic probes, sampling) for practical use, (3) demonstrate that these devices and methodology can be employed for on-line or in-situ monitoring of the status of anaerobic dehalogenating cultures in laboratory systems, and (4) develop new sensing species, methods, instrumental components and sensor designs for on-line monitoring of the status of dechlorinating systems in columns and PAMs packed with soil, microcosm bottles, and sub-surface systems in the field.

Approach

Redox indicators immobilized on transparent films have been shown to be able to differentiate between different microbial redox levels and to predict whether conditions are appropriate for reductive dechlorination to occur. These redox indicators, which are incorporated into flow sensors and fiber optic probes, will be deployed in collaborative experiments for calibration and demonstration of their applicability. These experiments will involve continuous monitoring of the redox conditions of cultures inside columns and PAMs packed with soil and enriched with halorespiratory cultures as a tool for spatial monitoring of dechlorination and to improve conditions necessary for effective dechlorination of PCE and TCE. The design and characteristics of the redox sensor monitoring systems will be improved for low oxygen permeation and portability for easy operation in the lab and field. In addition, we seek to investigate alternative sampling/reagent/detection systems, quantitative measurement of concentrations of reductants, and fiber optic sensors. Other probe species such as quinones may provide unique information about dechlorinating activity.

Status

We have continued to improve portable flow monitoring systems based on immobilized redox indicators and used them to examine redox conditions in microcosm bottles containing a dechlorinating culture (Evanite culture). Oxygen contamination has been reduced to the point that complete dechlorination is now achieved in microcosm bottles with continual redox monitoring in a time period about 50% longer than without monitoring. Reduction of the indicator thionine indicates conditions are appropriate for dechlorination and ethene production is typically observed when the indicator cresyl violet is approximately half reduced.

We developed a new method to determine the “reductive capacity” or “effective concentrations of reductants” in aqueous anaerobic samples taken from microcosm bottles, soil columns, and physical aquifer models (PAMs). A small volume of deaerated redox indicator solution in a septum-sealed, spectrometer cuvette is mixed and reacted with an aqueous sample obtained with a gas-tight syringe. Reductants in the sample reduce the indicator if the formal potential of the reductant couple is equal or below that of the indicator. From the decrease in absorbance of the indicator, the “reductive capacity” can be calculated, which is typically 200 to 600 μM for active microcosms. We anticipate the eventual automation of this measurement to allow for continuous monitoring.

We have begun to employ a fiber optic probe with immobilized redox indicator film at its tip to monitor redox status. The probe is used is conjunction with a light source and CCD spectrometer to monitor the absorbance of the indicator. This probe can be easily positioned in soil columns and PAMs and provides for true in-situ sampling. Redox indicators placed on the fiber optic probe respond comparably to those installed in flow cells and connected by flow loops.

To evaluate sensors and probes, we have constructed a PVC-based column with suitable ¼-28 ports for installation of redox flow monitoring setups and ½-20 ports to install the fiber optic probe. The column was recently packed with sediment from the Hanford site and inoculated with the Evanite culture. As observed during previous microcosm experiments with the Evanite culture, the indicator cresyl violet is about half reduced at all ports indicating suitable conditions for dehalogenation. Also, we have successfully used the redox flow sensor for monitoring conditions in PAMs and columns in labs in environmental engineering.

We have begun to probe the applications of other redox indicators, particularly quinones, to the array of indicators available to study environmental redox processes. Quinones are of particular interest as they participate in numerous cellular reactions and appear promising for determining “reductive capacity”. Also, we have begun evaluating long-path cells and automated syringes for improved on-line measurements of redox-active species (e.g., S(-II), Fe(+II)) and for push-pull sensing methods.

Awards

Tartar Summer Research Fellowship, Peter Ruiz-Haas (2003).

Students Working on the Project

Peter Ruiz-Haas, Ph.D. student, Department of Chemistry, Oregon State University, the primary student working on the project.

Defne Cakin, Ph.D. student, Department of Chemistry, Oregon State University, working on developing new monitoring techniques for the project.

Anthony Scott, Ph.D. student, Department of Chemistry, Oregon State University, working on automating procedures for the project.

Journal Articles:

No journal articles submitted with this report: View all 7 publications for this subproject

Supplemental Keywords:

RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Waste, TREATMENT/CONTROL, Environmental Chemistry, Treatment Technologies, Remediation, Environmental Microbiology, Hazardous Waste, Bioremediation, Ecological Risk Assessment, Environmental Engineering, Hazardous, plant-based remediation, degradation, contaminated sediments, microbial degradation, biodegradation, contaminated soil, contaminants in soil, phytoremediation, plant-microbe system, bacterial degradation, groundwater

Relevant Websites:

http://wrhsrc.oregonstate.edu/ Exit

Progress and Final Reports:

Original Abstract
  • 2002
  • 2003
  • 2005 Progress Report
  • Final

  • Main Center Abstract and Reports:

    R828772    HSRC (2001) - Western Region Hazardous Substance Research Center for Developing In-Situ Processes for VOC Remediation in Groundwater and Soils

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R828772C001 Developing and Optimizing Biotransformation Kinetics for the Bio- remediation of Trichloroethylene at NAPL Source Zone Concentrations
    R828772C002 Strategies for Cost-Effective In-situ Mixing of Contaminants and Additives in Bioremediation
    R828772C003 Aerobic Cometabolism of Chlorinated Aliphatic Hydrocarbon Compounds with Butane-Grown Microorganisms
    R828772C004 Chemical, Physical, and Biological Processes at the Surface of Palladium Catalysts Under Groundwater Treatment Conditions
    R828772C005 Effects of Sorbent Microporosity on Multicomponent Fate and Transport in Contaminated Groundwater Aquifers
    R828772C006 Development of the Push-Pull Test to Monitor Bioaugmentation with Dehalogenating Cultures
    R828772C007 Development and Evaluation of Field Sensors for Monitoring Bioaugmentation with Anaerobic Dehalogenating Cultures for In-Situ Treatment of TCE
    R828772C008 Training and Technology Transfer
    R828772C009 Technical Outreach Services for Communities (TOSC) and Technical Assistance to Brownfields Communities (TAB) Programs
    R828772C010 Aerobic Cometabolism of Chlorinated Ethenes by Microorganisms that Grow on Organic Acids and Alcohols
    R828772C011 Development and Evaluation of Field Sensors for Monitoring Anaerobic Dehalogenation after Bioaugmentation for In Situ Treatment of PCE and TCE
    R828772C012 Continuous-Flow Column Studies of Reductive Dehalogenation with Two Different Enriched Cultures: Kinetics, Inhibition, and Monitoring of Microbial Activity
    R828772C013 Novel Methods for Laboratory Measurement of Transverse Dispersion in Porous Media
    R828772C014 The Role of Micropore Structure in Contaminant Sorption and Desorption