Technology:
Bioremediation
Research on MTBE/TBA Degraders:
- Methanotrophs Study - study of two methanotrophic microorganisms, Methylosinus trichosporium OB3b and Methylosinus sporium, grown with methane as the single carbon source.
- Long-term In Situ Enrichment of TBA Degraders - study attempted to isolate TBA degraders from a chemical manufacturing site where TBA degraders in the range of 67 to 460,000 degrader per gram of sediment had been reported over a 10 year period
- Cultures Using MTBE as Growth Substrate - tested the Pelorus Environmental and Biotechnology Corp. (PEL) presumed pure culture (PEL-Pg) and the PEL consortium culture (PEL-CON); derived from leaking underground fuel tank (LUFT)-sediment samples and reportedly used MTBE as the sole carbon and energy source.
- Culture Derived from Biofilter - used biomass from an experimental biofilter from the Joint Water Pollution Control plant in Whittier, California; material observed to rapidly degrade >90% MTBE after a one year adaptation period.
Palo Alto LUFT Sites Screening Study:
- Used soil (sediment) and groundwater samples from a site in Palo Alto (collected at a depth of 18-26 feet where aqueous MTBE concentrations were in the low ppm range)
- Microcosms constructed from these materials either mimicked the anaerobic conditions prevailing at the site, or contained various amendments ranging from nutrients, to oxygen, to microbial biomass
- The groundwater used to construct the microcosms was first sparged to drive off volatile contaminants and then respiked to yield an initial aqueous MTBE concentration in the microcosm of about 420 g/L; microcosms were incubated for 3 months at 20oC and 6 rpm.
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Cleanup Authority:
Not identified
Point of Contact:
Rolf Halden, Ph.D., P.E.
Lawrence Livermore
National Laboratory (LLNL)
7000 East Ave.
P. O. Box 808, L-542
Livermore, CA 94551
Telephone: (925) 422-0655
Fax: (925) 423-7998
E-mail: halden1@llnl.gov |
Contaminants:
MTBE |
Waste Source:
Leaking underground fuel storage tanks |
Type/Quantity of Media Treated:
Soil and Groundwater |
Purpose/Significance of Application:
Research on microbial organisms to degrade MTBE in soil and groundwater |
Regulatory Requirements/Cleanup Goals:
Studies were conducted to evaluate the potential for difference microbial cultures to degrade MTBE in soil and groundwater. No specific treatment goals were identified. |
Results:
Research on MTBE/TBA Degraders:
-Methanotrophs Study - in resting cell assays, both organisms failed to degrade detectable amounts of TBA, MTBE, ethyl tert butyl ether (ETBE), diisopropyl ether (DIPE), and tert amyl methyl ether (TAME).
- Long-term In Situ Enrichment of TBA Degraders - no microorganisms were detected that could grow on minimal medium using TBA as the sole carbon and energy source.
- Cultures Using MTBE as Growth Substrate - during testing, the PEL-Pg culture was found to be a consortium of two different strains; neither of these two isolates nor the PEL-CON culture grew on MTBE/TBA or degraded these compounds
- Culture Derived from Biofilter - MTBE and TBA was degraded; however, microbial growth associated with MTBE depletion was extremely slow and resulted in undesirable cell clumping, potentially limiting applicability
Palo Alto LUFT Sites Screening Study:
- MTBE generally persisted under anaerobic conditions; the addition of ORC® and BioPetro did not stimulate MTBE degradation under anaerobic conditions
- MTBE was degraded completely in live, aerobic microcosms; however, the presence of additional carbon sources (sucrose contained in the BioPetro microcosms, isopropanol, and pasteurized cells) inhibited intrinsic MTBE biodegradation. |
Cost Factors:
No cost data were provided |
Description:
Researchers at Lawrence Livermore National Laboratory (LLNL) conducted several studies to evaluate the potential of various microorganisms to degrade MTBE in soil and groundwater. Research studies were performed on MTBE/TBA Degraders using different microbial cultures, including several that had been observed to degrade MTBE in other settings. In addition, a study was conducted to assess the potential use of intrinsic and/or engineered in situ bioremediation for the restoration of MTBE-impacted soils and groundwater at leaking underground fuel tank (LUFT) sites. The study locations, all situated in Northern California, were identified by the Santa Clara Valley Water District and the San Francisco California Regional Water Quality Control Board as high risk sites, based on their proximity to public drinking water wells and/or the presence of extremely high concentrations of MTBE in shallow groundwater. The overall goal of the study was to provide general conclusions concerning the fate of MTBE at LUFT sites.
The results showed that two methanotrophic microorganisms did not transform MTBE, TBA, ETBE, DIPE, and TAME. In addition, long-term enrichment under site-specific conditions may fail to produce strains that effectively degrade TBA/MTBE. According to the researchers, careful selection of experimental media is important to identify "real" MTBE degraders, and fast-growing MTBE degraders that are needed for bioaugmentation are currently not available. Results of the Palo Alto study indicate that MTBE may biodegrade naturally at LUFT sites in some instances when conditions are favorable (e.g., aerobic conditions, no BTEX compounds present). |
