Anaerobic Biodegradation of MTBE at a Gasoline Spill Site

Abstract

To manage risk or to implement natural attenuation as a remedy, regulatory agencies must understand the processes that attenuate methyl‐tert‐butyl ether (MTBE) in ground water. Most case studies and laboratory studies in the literature indicate that natural biodegradation is not important; however, recent reports indicate that natural biodegradation of MTBE plays an important role under certain conditions. In an MTBE plume at a retail gasoline station in Parsippany, New Jersey, the long‐term monitoring data indicated that the concentration of MTBE was slowly declining over time in the wells that were within the footprint of the plume. The ratio of tert‐butyl alcohol (TBA) to MTBE increased with distance from the source area, and the ratio of TBA to MTBE in individual monitoring wells in the plume increased over time. This anecdotal evidence of natural biodegradation of MTBE to TBA at field scale was confirmed with a microcosm study. Core material from the interior of the plume was used to construct the microcosms. Following an initial lag period of 58 d, the concentration of MTBE decreased from more than 1460 μg/L to less than 10 μg/L within 199 d of incubation. As concentrations of MTBE declined in the microcosms, concentrations of TBA increased. The decrease in concentration of MTBE in the microcosms could be accounted for by an increase in the concentration of TBA.

Mineralization of methyl tert-butyl ether and other gasoline oxygenates by Pseudomonads using short n-alkanes as growth source

“…Alkyl ethers are stable molecules (DG of the ether bond formation is 360 kJ mol -1 ) and the high-energy demand for MTBE degradation is reflected by the low biomass yield efficiency (Fortin et al 2001). Initial studies showed MTBE was highly recalcitrant but recently some authors have demonstrated that certain bacteria can degrade MTBE as their sole carbon and energy source (Hanson et al 1999;Hatzinger et al 2001;Ferreira et al 2006) or in anaerobic conditions (Wilson et al 2005).…”

Modern geochemical and molecular tools for monitoring in-situ biodegradation of MTBE and TBA

“…Positive results were obtained with nitrate, sulfate, Fe 3+ , Mn 4+ and in methanogenic microcosms, and in the majority of cases MTBE was not completely mineralized. Mormile et al (1994), Somsamak et al (2001Somsamak et al ( , 2005Somsamak et al ( , 2006 and Wilson et al (2005a) reported stoichiometric accumulation of TBA as MTBE was depleted (biotransformation to TBA occurred rather than complete mineralization). TBA biodegradation was apparent in a study by Yeh and Novak (1994), and in several microcosm studies with 14 C-MTBE or 14 C-TBA substrate (Bradley et al 2002).…”

Identification of tertiary butyl alcohol (TBA)-utilizing organisms in BioGAC reactors using 13C-DNA stable isotope probing

“…Although TBA is often only slowly biodegraded under anaerobic conditions (Wilson et al 2005), rapid aerobic TBA biodegradation has been demonstrated in microcosm studies using stream bed sediments (Bradley et al 1999), surface water sediments (Bradley et al 2002) and various cultures (Deeb et al 2003;Fortin et al 2001;François et al 2002;Hanson et al 1999;Hatzinger et al 2001;Kharoune et al 2001;Mo et al 1997;Piveteau et al 2001;Salanitro et al 1994;Steffan et al 2000). Several pure cultures of aerobic TBA-utilizing bacteria have also been isolated and characterized.…”