Grantee Research Project Results
2001 Progress Report: Assessment of Biotic and Abiotic Processes Controlling the Fate of Chlorinated Solvents in Mixed-Waste Under Iron- and Sulfate-Reducing Conditions Using Laboratory and In Situ Microcosms
EPA Grant Number: R825958Title: Assessment of Biotic and Abiotic Processes Controlling the Fate of Chlorinated Solvents in Mixed-Waste Under Iron- and Sulfate-Reducing Conditions Using Laboratory and In Situ Microcosms
Investigators: Hayes, Kim F. , Adriaens, Peter , Barcelona, Michael J.
Institution: University of Michigan
EPA Project Officer: Aja, Hayley
Project Period: November 17, 1997 through November 16, 2000
Project Period Covered by this Report: November 17, 2000 through November 16, 2001
Project Amount: $449,975
RFA: EPA/DOE/NSF/ONR - Joint Program On Bioremediation (1997) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management
Objective:
The major objective of this research project is to evaluate the relative importance of biotic and abiotic reductive dechlorination processes under iron- and sulfate-reducing conditions in both simple and mixed waste systems.
Progress Summary:
The main focus of this project period was to: (1) finish laboratory work related to abiotic and biotic dechlorination studies under iron and sulfate reducing conditions, and (2) conduct a field experiment of the potential for reductive dechlorination by reduced iron minerals using in situ microcosm (ISM).
Dechlorination studies were performed in combined abiotic and biotic systems (i.e., in systems in which the organisms and the solids they produced were both present). In one such system representative of iron reducing conditions, the transformation of carbon tetrachloride (CT) by magnetite and G. metallireducens was investigated. Using the relative yield of mineral surface area to total protein during growth as a basis of comparison, the surface area and protein normalized rate constants suggested that the predominant means by which G. metallireducens induces CT transformation is through the formation of reactive magnetite surfaces rather than via co-metabolic mechanisms. In a similar study representing sulfate reducing conditions, the transformation of CT by biogenic mackinawite and the organism D. vulgaris was observed. Similar to the iron reducing system, under sulfate reducing conditions, the surface mediated transformations by FeS was found to be more significant than the transformation caused by co-metabolic pathways. The implication of these studies for natural systems is that a demonstrated biological dependence for contaminant transformation does not necessarily indicate direct biological mediation. In many instances, in fact, it may be that highly reactive solids formed by biological activity are the primary pathway for dechlorination, rather than by direct co-metabolic transformation.
During this project period, ISM studies also were performed at the FT-2 (Fire Training site) at Wurtsmith Air Force Base to determine the relative importance of abiotic and biotic pathways under sulfate reducing conditions. At this site, trichlorethylene (TCE) and CT (at 2 ppm), Br (200 ppm), NaN3 (0.2 percent), sulfate (50 µg/L), lactate (400 µg/L), and an FeS slurry (10 g/L) were injected in different combinations in eight different ISMs to simulate controls and abiotic, biotic, and combined system conditions. Two ISMs controls were set up (one shallow and one deep) in which only the contaminants and bromide tracer were added to assess background transformations at the two different depths. Two other ISMs were used as abiotic controls in which in addition to the contaminants and bromide tracer, NaN3 (to kill bacteria) and sulfate were added at the two different depths. Four additional ISMs were set up for two biotic at shallow depths and two combined abiotic/biotic at deep depths by adding lactate to two of the microcosms, and FeS and lactate to the remaining two. NaN3 also was added to one shallow and one deep sampling location. The injection of the various reagents into the eight ISMs was implemented on November 10, 2000. Two sampling events were performed after that, one on November 27, 2000, and another on January 4, 2001. The extracted samples were monitored for disappearance of TCE and CT, and for the products acetylene, CS2 (known products of abiotic transformation of TCE and CT by FeS), CO, and CH4 (known products of abiotic transformation of CT by magnetite). Br, pH, sulfide, and iron also were monitored during the two sampling times. Disappearance of both TCE and CT was indicated on all ISMs, but the results concerning relative importance of abiotic and biotic dechlorination were inconclusive for the short duration of the study and the two sampling periods. Due to the scheduled closing of Wurtsmith Air Force Base in 2002, follow up studies could not be performed.
Future Activities:
As this was the last year of the project, the work performed during this project period completed the objectives and scope as set forth in the original project description.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
| Other project views: | All 48 publications | 5 publications in selected types | All 5 journal articles |
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Butler EC, Hayes KF. Factors influencing rates and products in the transformation of trichloroethylene by iron sulfide and iron metal. Environmental Science & Technology 2001;35(19):3884-3891. |
R825958 (2001) R825958 (Final) |
not available |
Supplemental Keywords:
reductive dechlorination, mixed-waste, groundwater, chlorinated solvents, heavy metals, reduced iron minerals, iron sulfide minerals, iron reducing conditions, sulfate reducing conditions., RFA, Scientific Discipline, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Chemical Engineering, Bioavailability, Environmental Chemistry, Fate & Transport, Ecology and Ecosystems, Ecological Risk Assessment, Bioremediation, fate and transport, dechlorination, contaminants in soil, contaminant release, contaminated aquifers, chlorinated solvents, metal compounds, heavy metalsRelevant Websites:
http://www.engin.umich.edu/dept/cee/research/hayes/ Exit
http://www.engin.umich.edu/dept/cee/research/adriaens/ Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.