• Journal of Environmental Health Sciences
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• v.34 no.6
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• pp.403-413
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• 2008

Toxic effect of methyl tert-butyl ether (MTBE), tert-butyl alcohol (TBA) and formaldehyde (FA) on microbial activity and diversity was compared in rice field, leek patch, and tidal mud flat soil samples. MTBE, TBA and FA with different concentrations were added into microcosms containing these soil samples, and placed at room temperature for 30 days. Then the microbial activities such as dehydrogenase and viable cell numbers and microbial community using a DGGE (Denaturing gradient gel electrophoresis) fingerprinting method were measured. Among the samples, dehydrogenase activity in rice field was inhibited the most by MTBE, TBA and FA. The toxic effect was higher according to the following orders: FA > MTBE > TBA. Dominant species in the microcosms contaminated with MTBE, TBA and FA were Chloroflex, Bacilli, gamma-proteobacteria in the rice field sample, Sphingobacteria, Flavobacteria, Actinobacteria, Bacilli, gamma-proteobacteria in the leek patch sample, and Sphingobacteria, Flavobacteria, delta-proteobacteria, gamma-proteobacteria in the tidal mud flat sample.

• Environmental Analysis Health and Toxicology
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• v.21 no.2 s.53
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• pp.93-102
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• 2006

Methyl tert-butyl ether (MTBE), an octane booster that is added to the reformulated gasoline, has been a widespread contaminant in aquatic ecosystem. MTBE is a recalcitrant pollutant having low biodegradability. Due to its higher water solubility and low octanol-water partition coefficient, it can be rapidly transported to the surrounding water environment. Also, MTBE is a known animal carcinogen, and is classified as a possible human carcinogen by U. S. Environmental Protection Agency. The adverse effect of MTBE to aquatic biota was widely reported. In Korea, the recent detection of MTBE in groundwater near gasoline filling stations has drawn concern to public health and ecosystem. To address this concern, the effect of MTBE to human health and ecosystem was discussed in this review. Also, ecotoxicity data of MTBE for fish, invertebrates, and algae were extensively compared to estimate the hazard concentration 5($HC_5$) of MTBE as a screening level.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.8
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• pp.767-773
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• 2010

In recent years, there has been considerable concern over the release of methyl tert-butyl ether (MTBE), a gasoline additive, into the aquifers used as potable water sources. MTBE readily dissolves in water and has entered the environment via gasoline spills and leaking storage tanks. In this study air stripping and ozonation of MTBE in aqueous solution were performed in a laboratory scale batch reacter. The mass transfer rate (N) was evaluated and a values about $1.24{\times}10^{-6}\;mol{\cdot}sec^{-1}$ was found. In the ozonation of MTBE a 8.3% decrease of the COD and a 6.5% decrease of the TOC lead to BOD/COD = 0.03. The peudo first-order rate constants of the ozonation of MTBE was $3.75{\times}10^{-5}\;sec^{-1}$. The resulting Ea of 4.80 kcal；mol-1 was observed for molecular ozone reactions.

• Microbiology and Biotechnology Letters
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• v.36 no.4
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• pp.336-342
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• 2008

The effect of methyl tert-butyl ether (MTBE) and its metabolites like tert-butyl alcohol (TBA), and formaldehyde (FA) on microbial activity and diversity in tidal mud flat was studied. MTBE, TBA, and FA with different concentrations were added into microcosms containing tidal mud samples, and placed at room temperature for 30 days. Then the physico-chemical properties such as pH, moisture contents and organic matter contents in the microcosms were measured. In addition, the total viable cell number and dehydrogenase activity were measured. Bacterial communities in the microcosms were monitored using a 16S rRNA-PCR-DGGE (Denaturing gradient gel electrophoresis) fingerprinting method. As a result, the exposure concentrations of MTBE and its metabolites showed no correlation with the physico-chemical factors (P>0.05). Dehydrogenase activity and total viable cell number were decreased with increasing MTBE, TBA and FA concentrations (P<0.05). The toxic effect was higher the following order: FA > MTBE > TBA. Dominant species in the microcosms contaminated with MTBE and its metabolites were Sphingobacteria, Flavobacteria, delta-proteobacteria, gamma-proteobacteria. The diversity of bacterial community was not significantly influenced by MTBE and its metabolites.

• Journal of Soil and Groundwater Environment
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• v.19 no.5
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• pp.9-17
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• 2014

This paper reported the use of real-time polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), and the culture-based method in the intrinsic bioremediation study at a petroleum contaminated site. The study showed that phenol hydroxylase gene was detected in groundwater contaminated with benzene, toluene, ethylbenzene, xylene isomers (BTEX) and methyl tert-butyl ether (MTBE). This indicated that intrinsic bioremediation occurred at the site. DGGE analyses revealed that the petroleum-hydrocarbon plume caused the variation in microbial communities. MTBE degraders including Pseudomonas sp. NKNU01, Bacillus sp. NKNU01, Klebsiella sp. NKNU01, Enterobacter sp. NKNU01, and Enterobacter sp. NKNU02 were isolated from the contaminated groundwater using the cultured-based method. Among these five strains, Enterobacter sp. NKNU02 is the most effective stain at degrading MTBE without the addition of pentane. The MTBE biodegradation experiment indicated that the isolated bacteria were affected by propane. Biodegradation of MTBE was decreased but not totally inhibited in the mixtures of BTEX. Enterobacter sp. NKNU02 degraded about 60% of MTBE in the bioreactor study. Tert-butyl alcohol (TBA), acetic acid, 2-propanol, and propenoic acid were detected using gas chromatography/mass spectrometry during MTBE degraded by the rest cells of Enterobacter sp. NKNU02. The effectiveness of bioremediation of MTBE was assessed for potential field-scale application.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.136-139
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• 2001

In this study, we have examined potential degradation of MTBE (methy1 tert-butyl ether) by pure culture ENV425 and mixed culture isolated from gasoline contaminated soil using n-butane as the sources of carbon and energy. The results described in this study suggest that MTBE is degraded cometabolically by ENV425 and mixed culture grown n-butane, and the disappearance of TBA after complete degradation of MTBE suggest the further degradation of TBA. Butane and MTBE degradation was completely inhibited by acetylene, which indicated that both substrates were degraded by butane-utilizing bacteria. MTBE was degraded ENV425 and mixed culture grown n-butane, and TBA (tert-butyl alcohol) was produced as product of MTBE oxidation. TBA production was accounted 54.7% and 58.6% for MTBE oxidation by ENV425 and mixed culture, respectively. The observed maximal transformation yield (T$_{y}$) were 44.7 and 34.0 (nmol MTRE degraded/$\mu$mol n-butane Utilized) by ENV425 and mixed culture, respectively.y.

• Journal of Environmental Health Sciences
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• v.34 no.5
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• pp.387-394
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• 2008

The toxicity of methyl tert-butyl ether (MTBE), tert-butyl alcohol (TBA) and formaldehyde (FA) on the indigenous microbial community in forest soil was studied. MTBE, TBA and FA with different concentrations were added into microcosms containing forest soil samples. After 10 and 30 days, total viable cell number and dehydrogenase activity in the microcosms were evaluated. Bacterial communities in the microcosms were also analyzed using a denaturing gradient gel electrophoresis (DGGE). Dehydrogenase activity and total viable cell number were decreased according to the increase of MTBE, TBA and FA concentrations (P<0.05). FA toxicity was the highest, but TBA toxicity was the lowest. The results of principal component analysis using DGGE fingerprints showed that the microbial communities contaminated MTBE, TBA and FA were grouped by exposure time not exposure concentration. Dominant species in the microcosms were as follows: Photobacterium damselae sub sp. and Bacillus sp. KAR28 for MTBE; Mycobacterium sp. and Uncultured Clostridium sp. for TBA; and Uncultured Paenibacillaceae bacterium and Anxynobacillus, Flavithermus for FA.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.31-37
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• 2002

미국의 캘리포니아에서는 1995년도부터 휘발유의 옥탄가 향상제로 첨가되는 메틸 터셔리 부틸 이스(Methyl tert-Butyl Ether, MTBE)의 사용을 금지시켰다. MTBE의 사용이 금지된 가장 큰 이유는 MTBE의 물에 패한 용해도가 높아서 주유소 지하저장 탱크를 통하여 지하수를 오염시키고 저장탱크 바닥의 물을 배출시킴으로 인하여 지표수도 오염시키는 문제가 있었기 때문이다.(중략)

• Journal of Soil and Groundwater Environment
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• v.6 no.3
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• pp.31-41
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• 2001

In this study, we have examined the potential degradation of MTBE(methyl tert-butyl ether) by pure culture ENV425 and mixed culture obtained from gasoline contaminated soil using n-butane as the sources of carbon and energy. The results described in this study suggest that MTBE is degraded cometabolically by ENV425 and mixed culture grown on n-butane. Butane and MTBE degradation was completely inhibited by acetylene, which indicated that both substrates were degraded by butane monooxygenase. These cultures grown on n-butane generated TBA (tert-butyl alcohol) as a metabolite of MTBE oxidation. TBA Production was accounted 54.7% and 58.6% for MTBE oxidation by ENV425 and mixed culture, respectively. In resting cell experiments, however, TBA and TBF were detected as the oxidation products of MTBE by ENV425 and mixed culture. The observed maximal MTBE degradation rates were 52.3 and 62.3 (nmol MTBE degraded/hr/mg TSS) by ENV425 and mixed culture, respectively, and the observed maximal transformation yields ($T_y$) were 44.7 and 34.0 (nmol MTBE degraded/$\mu$mol n-butane utilized), and the observed maximal transformation capacities ($T_c$) were 199 and 226 ($\mu$mol MTBE degraded/mg TSS used).

• Journal of Soil and Groundwater Environment
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• v.11 no.6
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• pp.69-75
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• 2006

Improper disposal of petroleum and spills from underground storage tanks have created large areas with highly toxic contamination of the soil and groundwater. Methyl tert-butyl ether (MTBE) is widely used as a fuel additive because of its advantageous properties of increasing the octane value and reducing carbon monoxide and hydrocarbon exhausts. However, MTBE is categorized as a possible human carcinogen. This research investigated the Modified Photo-Fenton system which is based on the Modified Fenton reaction and UV light irradiation. The Modified Fenton reaction is effective for MTBE degradation near a neutral pH, using the ferric ion complex composed of a ferric ion and environmentally friendly organic chelating agents. This research was intended to treat high concentrations of MTBE; thus, 1,000 mg/L MTBE was chosen. The objectives of this research are to find the optimal reaction conditions and to elucidate the kinetic and mechanism of MTBE degradation by the Modified Photo-Fenton reaction. Based on the results of experiments, citrate was chosen among eight chelating agents as the candidate for the Modified Photo-Fenton reaction because it has a relatively higher final pH and MTBE removal efficiency than the others, and it has a relatively low toxicity and is rapidly biodegradable. MTBE degradation was found to follow pseudo-first-order kinetics. Under the optimum conditions, [$Fe^{3+}$] : [Citrate] = 1 mM: 4 mM, 3% $H_2O_2$, 17.4 kWh/L UV dose, and initial pH 6.0, the 1000 ppm MTBE was degraded by 86.75% within 6 hours and 99.99% within 16 hours. The final pH value was 6.02. The degradation mechanism of MTBE by the Modified Photo-Fenton Reaction included two diverse pathways and tert-butyl formate (TBF) was identified to be the major degradation intermediate. Attributed to the high solubility, stability, and reactivity of the ferric-citrate complexes in the near neutral condition, this Modified Photo-Fenton reaction is a promising treatment process for high concentrations of MTBE under or near a neutral pH.