U.S. EPA Contaminated Site Cleanup Information (CLU-IN)


U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Dense Nonaqueous Phase Liquids (DNAPLs)

Detection and Site Characterization

Push-Pull

Abstracts of Journal Articles

Adobe PDF LogoField Push-Pull Test Protocol for Aerobic Cometabolism of Chlorinated Aliphatic Hydrocarbons
Kim, Y., M. Azizian, J. Istok, and L. Semprini, Oregon State Univ., Corvallis. Environmental Security Technology Certification Program, 83 pp, 2005

This protocol describes a newly developed field technology—the single-well push-pull test—for evaluating the feasibility of using in situ aerobic cometabolic processes to treat ground water contaminated with chlorinated solvent mixtures. Push-pull tests have been used to obtain quantitative information on a variety of aquifer physical, chemical, and microbiological characteristics, but have not previously been used to investigate aerobic cometabolic processes. This protocol describes how push-pull tests can be used to evaluate the potential for aerobic cometabolism of chlorinated aliphatic hydrocarbons using gaseous cometabolic substrates (e.g., propane) and soluble substrates (e.g., toluene). The protocol introduces the field test methodology, describes how field push-pull tests are performed, explains how to prepare test solutions, and summarizes the analytical methods used to measure tracer, nutrient, substrate, and chlorinated solvent/transformation product concentrations in field samples collected during the tests. Case studies of field work conducted at McClellan AFB, CA, and Fort Lewis, WA, are provided to illustrate additional details about the push-pull test methodology.

Monitoring Bioaugmenation with Single Well Push-Pull Tests in Sediment Systems Contaminated with Trichloroethene
Lee, Jae Hyuk, Mark Dolan, Jonathan Istok, & Jennifer Field, Oregon State Univ., Corvallis. Fourth SETAC World Congress, 25th Annual Meeting in North America, 14-18 November 2004, Portland, Oregon. Society of Environmental Toxicology and Chemistry, Pensacola, FL. Poster PH255, 2004

Bioaugmentation can be defined as the introduction of microorganisms to degrade a target compound in a contaminated medium. Despite successful bioaugmentation in bench- and field-scale studies, it still is not clear whether dechlorinating activity is due to indigenous or bioaugmented strains and whether the injected cultures have lesser or greater distribution around the injection wells. Microcosm studies conducted to compare the reductive dechlorination rates of trichloroethene (TCE) and trichlorofluoroethene (TCFE) in control sediments and sediments bioaugmented with a dechlorinating culture produced data that were then used to design intermediate-scale (125 cm) push-pull laboratory tests conducted in physical aquifer models (PAMs). Push-pull test methodology, TCFE, and the PAMs were used to monitor the progress of bioaugmentation in PAMs containing TCE-contaminated sediment. The rate and products of TCFE transformation were determined by conducting push-pull tests in the PAM. The spatial distribution of the dechlorinating culture within the PAM correlated with concentrations of TCFE and TCE dechlorination products. No transformation products of TCFE and TCE were observed for sediment controls that did not receive the dechlorinating culture.

Adobe PDF LogoPush-Pull Tests Evaluating In Situ Aerobic Cometabolism of Ethylene, Propylene, and cis-1,2-Dichloroethylene
Kim, Y. (Korea Univ., Choong Nam, Korea); J.D. Istok and L. Semprini (Oregon State Univ., Corvallis). Journal of Contaminant Hydrology, Vol 82 No 1-2, p 165-181, 5 Jan 2006

In situ aerobic cometabolic transformations of ethylene, propylene, and cis-1,2-dichloroethylene (c-DCE) by microorganisms stimulated on propane were examined in groundwater contaminated with c-DCE and trichloroethene (TCE). Field push/pull tests provided in situ measurements. The tests involved the injection of site groundwater amended with a bromide tracer and combinations of propane, dissolved oxygen (DO), nitrate, ethylene, propylene, c-DCE, and TCE into existing monitoring wells and sampling the same wells over time. Mass balance and transformation rate calculations were performed after adjusting for dilution losses using measured tracer concentrations. Initial rates of propane utilization were very low, but the rates increased substantially following sequential additions of propane and DO. The injected ethylene and propylene were transformed to the cometabolic byproducts ethylene oxide and propylene oxide, whereas these transformations were inhibited in the presence of co-injected acetylene, a known monoxygenase mechanism-based inactivator. These results suggest that a series of push/pull tests performed with nontoxic chemical probes can be useful for detecting and monitoring in situ aerobic cometabolism of chlorinated aliphatic hydrocarbons.

"Push-Pull" Tests for Monitoring Bioaugmention with Reductive Dechlorinating Cultures
Research Brief from the Western Hazardous Research Center, Brief No 5, Sep 2004

Bioaugmentation is a promising remediation approach for remediating contaminated ground water in which the aquifer is injected with a microbial community that can degrade high contaminant concentrations in situ. Successful biaugmentation requires careful monitoring. Practitioners need a way to quantitatively track changes in the microbial community, the extent of bioaugmentation, and the treatment's effectiveness. Researchers from Oregon State University--Jack Istok, Jennifer Field, and Mark Dolan--are developing a single well "push-pull" test to monitor the effectiveness of the treatment in anaerobic source zones. The push-pull test involves injecting a test solution into an aquifer and then withdrawing the test solution and ground-water mixture. Comparisons of the "pushed" and "pulled" solutions provide information about the physical, chemical, and biological conditions within the aquifer. The researchers are focusing on using the method to monitor the cleanup of high concentrations of chlorinated solvents, such as tetrachloroethene and trichloroethene, by anaerobic reductive dechlorination.



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