Degradation Of Methyl Tertiary Butyl Ether Research Articles

Fabrication and photocatalytic activity of Fe3O4/SiO2/TiO2 magnetic nanoparticles removing MTBE from simulated water

ABSTRACT The removal of methyl tertiary butyl ether (MTBE) from simulated water is going to be a critical environmental issue. The aims of the present study are to synthesise the Fe3O4/SiO2/TiO2 magnetic nanoparticles (MNPs) and evaluate its efficiency for the removal of MTBE by UV/O3/Fe3O4/SiO2/TiO2 combined process (CP) from water. The MNPs were synthesised via modified method and characterised using XRD, SEM and EDS. Then, the effects of initial ozone concentration, pH, MNP concentration, initial MTBE concentration (C0) and irradiation time were evaluated. The findings depicted that the performance of CP is better than separate processes. The optimum condition with initial ozone concentration of 150 mg/L, pH of 8, MNP concentration of 0.1 g/L and C0 of 10 mg/L at 60 min irradiation time results in maximum degradation of MTBE up to 91.65%. Also, the mineralisation rate of MTBE was achieved 68% removal at the same condition. Kinetic profile presented that the reduction of MTBE was fitted into second-order kinetics model for all the runs. The findings illustrate the capabilities of CP as a reliable technology to remove MTBE contained in water.

Methyl tertiary butyl ether biodegradation by the bacterial consortium isolated from petrochemical wastewater and contaminated soils of Imam Khomeini Port Petrochemical Company (Iran)

Methyl tertiary butyl ether (MTBE) is a high soluble oxygenated supplement to fuel that may rapidly contaminate water and soil. Low biodegradability of this compound in the environment has led to more extensive efforts for finding powerful MTBE degrading microbial populations to be used in biological treatment of polluted waters and soils. The present study aimed to isolate MTBE degrading bacteria from petrochemical wastewater and soil of Mahsahar MTBE production site (Iran), and increasing their biodegradation potential in a bacterial consortium. Enrichment of degrading bacteria was done in basal salt media (BSM) containing 50–400 mg/l MTBE. The MTBE degradation pattern was assessed via gas chromatography (GC). The isolates were identified molecularly based on the sequence of 16S rRNA gene. The growth and degradation potential of bacterial consortium was optimized in different pH and temperatures. The best MTBE degrading bacteria were identified as Pseudomonas putida, Pseudomonas aeruginosa, and Enterobacter oryzendophyticus. The first order kinetics for MTBE degradation showed that the bacterial consortium was able to degrade 99.93% of MTBE during 15 days that was 6.08% higher than the most putative monoculture bacterium. The highest MTBE degradation by bacterial consortium was obtained at 30 °C and pH value of 7. The isolated bacterial consortium that involved novel MTBE degrading bacterial strains, decomposed high amounts of MTBE during 15 days of incubation in different temperatures and pH values without addition of co-catalytic substrate is proposed for cost effective removal of this pollutant from the environment.

A Laboratory-Based Case Study to Remove MTBE from Contaminated Water with Pure-WO<sub>3</sub> and Nano-WO<sub>3</sub> Catalysts Loaded with Ru and Pt

This article describes a laboratory-based case study to remove methyl tertiary butyl ether (MTBE) from contaminated water with tungsten oxide (WO3) catalysts loaded with ruthenium (Ru) and platinum (Pt) metals. Characterization of the synthesized catalysts were conducted by using the: (i) X-ray powder diffraction (XRD) data for the purity, (ii) visible light reaction condition for MTBE, (iii) solid-phase micro-extraction (SPME) technique incorporated with gas chromatography mass spectrometry (GC-MS) to assist the MTBE photo-oxidation process, (iv) catalyst syntheses from different concentrations of Ru in WO3, nano-WO3, Pt in nano-WO3, and (v) formation of byproducts during photocatalytic degradation of MTBE by using the GC-MS. The results revealed that the catalysts mainly consists of WO3 phase and there is no additional peaks from the metals, indicating that the Ru and Pt metals are well dispersed on WO3. Approximately 96% to 99% of the MTBE removal can quickly and accurately be achieved with a nanostructured WO3 catalyst loaded with Pt under visible light radiation between 2.5h and 3h. Moreover, with a nanocomposite WO3 catalyst loaded with Pt, photocatalytic MTBE removal is higher than with the pure WO3 catalyst loaded with Ru, and the pure nanostructured and micron-sized WO3. Finally, the formation of byproducts during the MTBE photocatalytic degradation revealed that the MTBE degradation essentially proceeds via formation of formic acid and 1,1-dimethylethyl ester before its complete degradation.

Employing response surface analysis using for photocatalytic degradation of MTBE by nanoparticles

Since groundwaters are a major source of drinking water, their pollution with organic contaminants such as methyl tertiary-butyl ether (MTBE) is a very significant issue. Hence, this research investigated the photocatalytic degradation of MTBE in an aqueous solution of TiO2-ZnO-CoO nanoparticle under UV irradiation. In order to optimize photocatalytic degradation, response surface methodology was applied to assess the effects of experimental variables such as catalyst loading, initial concentration of MTBE and pH on the dye removal efficiency. The optimal condition to achieve the best degradation for the initial concentration of 30.58 mg/L of MTBE was found at a pH of 7.68 and a catalyst concentration of 1.68 g/L after 60 min.

Treatment of water contaminated with methyl tertiary butyl ether using UV/chlorine advanced oxidation process

Methyl tertiary butyl ether (MTBE) is a widely used gasoline additive to improve the air quality by increasing the oxygen content of the fuel. After extensive use for some years in the USA, it was recognized as a groundwater contaminant. Several remediation techniques are available for the removal of MTBE from contaminated water systems. However, the inherent limitations of each removal technique makes further research promising. The aim of this study was to investigate the MTBE degradation in water with chlorine-based advanced oxidation process (AOP). A bench scale study was carried out by varying the experimental conditions such as UV radiation intensity, pH, chlorine doses, and treatment time. Free chlorine was used as a chemical oxidant in combination with low-pressure (LP) and medium-pressure (MP) mercury lamps to degrade MTBE in water. LP and MP UV/chlorine were able to degrade more than 99% of MTBE in deionized water within 15–30 min at pH 5 and 7, respectively. The MTBE removal in groundwater sample with LP UV/chlorine and MP UV/chlorine is greater than 99 and 90% after 30 min respectively. The electrical energy per order estimated for LP UV/chlorine and MP UV/chlorine to treat ground water sample was 4.01 and 54.67 kW h/m3 respectively. Chlorine-based AOP could be a promising technique for treating water contaminated with MTBE.

Effects of pH on the Kinetics of Methyl Tertiary Butyl Ether Degradation by Oxidation Process (H2O2/Nano Zero-Valent Iron/Ultrasonic)

Background: In advanced oxidation processes, pH has a significant effect on the removal efficiency of organic compounds. This study examined the effect of pH changes on the removal efficiency and kinetics of methyl tertiary butyl ether (MTBE) concentration in aquatic environment. Objectives: The primary objective of this study was to evaluate the effect of pH changes on removal kinetics of the mentioned compound, using H2O2/nZVI (nano zero-valent iron)/ultrasonic process, and its impact on the reaction rate. Materials and Methods: In order to create the right conditions for oxidation, first of all iron nanoparticles combined with H2O2 oxidizer were synthesized, and then they were subjected to ultrasound waves and used in MTBE oxidation. In MTBE removal via H2O2/nZVI/Ultrasonic process, the effects of some parameters such as contact time (2 to 60 minutes), concentration of hydrogen peroxide (5 to 20 mL/L), concentrations of nZVI (0.15 to 0.45 g/L), MTBE concentrations (50 to 750 mg/L), and pH (2 to 9) were investigated. MTBE concentration analysis was performed using gas chromatography (GC). Results: According to this study, the best removal efficiency of 50 mg/L MTBE concentration in 89.56% under oxidation condition occurred when H2O2 level equals to 10 mL/L, nZVI is 0.25 g/L at pH 3.5. The results showed that the increase or decrease of pH from 3.5 results in a loss of oxidation efficiency as well as reduction in the amount of kap. In addition, the logarithmic changes curve of MTBE concentration showed that MTBE oxidation in H2O2/nZVI/ultrasonic method follows pseudo first order reactions. Conclusions: Changes of pH could remarkably affect the efficiency and oxidation rate of MTBE. In particular, the amount of kap in terms of oxidation declines substantially by moving away from the optimum pH range. In this study, pH 3.5 was considered as the optimal pH in H2O2/nZVI/ultrasonic oxidation process, with the elimination of about 89.56% of the high MTBE concentration. In general, we can say that by adjusting pH in this range, the rate and efficiency of MTBE oxidation can be enhanced in H2O2/nZVI/ultrasonic method.

Removal of Methyl Tertiary-Butyl Ether (MTBE) from Aqueous Solution Using Sunlight and Nano TiO2

Methyl tertiary-butyl ether is a synthetic compound that was developed as a technological solution to a technology-derived problem created by air pollution from vehicle emissions. Methyl tertiary-butyl ether was added to gasoline with the intent to reduce air emissions, making the fuel burn cleaner. Unfortunately, use of this air-saving gasoline additive has created one of the most threatening and widespread environmental problems for the nation's drinking water supply. In this work, degradation of methyl tertiary-butyl ether in aqueous solution using the solar ultraviolet and TiO2 nano particles was investigated. Factors that affect photocatalytic removal of methyl tertiary-butyl ether, such as pH, TiO2, and methyl tertiary-butyl ether concentrations, were studied and optimum conditions were determined using the Taguchi method for designing the experiments. Results showed that the best conditions for the removing of methyl tertiary-butyl ether in the ultraviolet/TiO2 process are 2 g/l nano TiO2 and 50 ppm methyl tertiary-butyl ether, which leads to more than 88% removal of methyl tertiary-butyl ether in 120 min.

Nanocatalyst support of laser-induced photocatalytic degradation of MTBE

This study was undertaken to develop a methodology suitable for the direct removal and degradation of methyl tertiary butyl ether (MTBE) in water using different nano-catalysts supported laser based photo-oxidation process. For this purpose, nano-structured WO3 catalyst was synthesized in our laboratory and its photocatalytic activity for the demineralization of MTBE in water was compared with different catalysts such as ZnO, TiO2, Fe2O3 and NiO using 355 nm laser radiations generated by the third harmonic of Nd: YAG laser. The effect of laser irradiation time, amount of catalysts and pH were also investigated for the optimization of MTBE removal process. For 60 min of laser exposure time, the overall percentage of MTBE degradation was found to be 93%, 89%, 82%, 80% and 71% for WO3, ZnO, Fe2O3, NiO and TiO2, respectively. In addition the photonic efficiencies of different nano-structured catalysts toward degradation of MTBE were estimated, and they were found to follow the trend of WO3 > ZnO > Fe2O3 > NiO > TiO2.

폐영가철 투수성반응벽체를 이용한 Modified Fenton 산화에 의한 MTBE 처리연구

MTBE (Methyl tertiary-butyl ether) has been commonly used as an octane enhancer to replace tetraethyl lead in gasoline, because MTBE increases the efficiency of combustion and decreases the emission of carbon monoxide. However, MTBE has been found in groundwater from the fuel spills and leaks in the UST (Underground Storage Tank). Fenton's oxidation, an advanced oxidation catalyzed with ferrous iron, is successful in removing MTBE in groundwater. However, Fenton's oxidation requires the continuous addition of dissolved Fe 2+ . Zero-valent iron is available as a source of catalytic ferrous iron of MFO (Modified Fenton's Oxidation) and has been studied for use in PRBs (Permeable Reactive Barriers) as a reactive material. Therefore, this study investigated the condition of optimization in MFO-PRBs using waste zero-valent iron (ZVI) with the waste steel scrap to treat MTBE contaminated groundwater. Batch tests were examined to find optimal molar ratio of MTBE : H2O2 on extent to degradation of MTBE in groundwater at pH 7 with 10% waste ZVI. As the results, the ratio of optimization of MTBE to hydrogen peroxide for MFO was determined to be 1:300[mM]. The column experiment was conducted to know applicability of MFO-PRBs for MTBE remediation in groundwater. As the results of column test, MTBE was removed 87% of the initial concentration during 120days of operational period. Interestingly, MTBE was degraded not only within waste ZVI column but also within sand column. It means the aquifer may affect continuously the MTBE contaminated groundwater after throughout the waste ZVI barrier. The residual products showed acetone, TBF (Tert-butyl formate) and TBA (Tert-butyl acetate) during this test. The results of the present study showed that the recycled materials can be effectively used for not only a source of catalytic ferrous iron but also a reactive material of the MFO-PRBs to remove MTBE in groundwater. Key word : Waste Zero-Valent Iron, MTBE, Modified Fenton Oxidation, PRBs, MFO-PRBs

Laser-based photo-oxidative degradation of methyl tertiary-butyl ether (MTBE) using zinc oxide (ZnO) catalyst

Laser-induced photo-catalytic process for the removal of MTBE from water has been investigated in this study. We have studied the laser-based photo-oxidation of MTBE using ZnO semiconductor catalysts at 355 nm laser radiation generated by third harmonic of Nd: YAG laser. The effect of laser irradiation time, laser energy power, catalyst amount and pH parameters were investigated for the efficient removal of MTBE from water using ZnO catalyst. It was found that at pH value of 8, 300 mg of ZnO catalyst, 60 minutes laser irradiation time and 200 mJ of laser energy, delivered best results with maximum degradation of MTBE in water.

A Kinetic Model for the Aqueous Degradation of MTBE by Fe0/H2O2

Methyl tertiary-butyl ether (MTBE) is a possible human carcinogen that has been used as a gasoline oxygenate at concentrations of up to 15% by volume for about 45 years in the US. However, its high water solubility has exacerbated spills at gasoline stations, sometimes resulting in local groundwater MTBE contamination levels of over 100 mg/L. Advanced oxidation using Fe0 and H2O2 is a promising technique for mineralizing organic contaminants, but current understanding of the remediation chemistry needs to be improved to facilitate design of subsurface or engineered systems. A kinetic model for the degradation of MTBE in batch systems applying zero-valent iron (Fe0) andhydrogen peroxide (H2O2) oxidation in aqueous solution was developed. The model includes: H2O2 and water chemistry, iron speciation, and MTBE oxidation reactions. H2O2/water and MTBE degradation equilibrium and reaction rate parameters were taken from the literature. Reaction rate and equilibrium parameters for iron speciation were taken from the literature, or from our prior work. The rate constant for the dissolution of Fe0 was found from this work. The model was compared to experimental data from the literature for MTBE degradation using Fe0/H2O2

Removal of methyl tertiary butyl ether from wastewaters using photolytic, photocatalytic and microbiological degradation processes

Contamination of groundwater by methyl tertiary butyl ether (MTBE), that is detected in wastewater of petrochemical industry, is an increasing problem to water supply companies. The subjects of this research were the methods of photolytic, photocatalytic and microbiological degradation of methyl tertiary butyl ether (MTBE) dissolved in wastewaters. The effects of concentrated solar radiation simulated with sodium lamp (SONT UV 400) have been investigated in laboratory experiments. Our result indicated that bacteria Pseudomonas strain CY, isolated from the kerosene, and added alone, was able to gradually degrade MTBE and to decrease its concentration for 93.6% in 12 h. However, the percentage of photolytic degradation decrease in only 4 h was 99.2%. By adding Pseudomonas strain CY after 4 h of light treatment, the degradation was enhanced to 99.55% in additional 5 h. The photocatalytic process was performed in slurry-catalyst reactor with different concentrations of TiO 2 catalyst: 5, 0.5 and 0.25 g/L. The MTBE degradation producing carbon dioxide reached 91% in only 150 min, when 5 g/L of catalyst was used.

Degradation of methyl tertiary-butyl ether (MTBE) by anodic Fenton treatment

Degradation of MTBE, a common fuel oxygenate, was investigated using anodic Fenton treatment (AFT) and by comparison with classic Fenton treatment (CFT). The AFT system provided an ideal pH environment (2.5–3.5) for the Fenton reaction and utilized gradual delivery of ferrous iron and hydrogen peroxide, which was more efficient than batch CFT to degrade MTBE and its breakdown products. The optimized ratio of ferrous iron to hydrogen peroxide for AFT was determined to be 1:5 (in mmol). Depending on the initial concentration, MTBE was completely degraded by the optimized AFT in 4–8 min. The breakdown products found during the treatment of MTBE were acetone, t-butyl formate, t-butanol, methyl acetate, acetic acid, and formic acid, which were all completely degraded by the optimized AFT in 32 min. Based on the experimental results and other work reported in the literature, degradation mechanisms of MTBE and its breakdown products in AFT and CFT were proposed. Generally, reactions are initiated by H-abstraction by OH, generating carbon-centered radicals which undergo various reactions including α/β-scission within the radical, combination with oxygen, oxidation by ferric ion, and reduction by ferrous ion before generating the final oxidation products. Radical combination with oxygen (and the reactions thereafter) and radical oxidation by ferric ion are believed to be the most important pathways in the overall fate of the generated radicals, while radical reduction by ferrous ion is the least important. By elucidating the reaction kinetics and mechanisms of MTBE degradation in the anodic Fenton system, this study offers a potential remediation technique for treating MTBE-contaminated wastewater.

Biotic and Abiotic Transformations of Methyl tertiary Butyl Ether (MTBE) * (6 pp)

Methyl tertiary butyl ether (MTBE) is a fuel additive which is used all over the world. In recent years it has often been found in groundwater, mainly in the USA, but also in Europe. Although MTBE seems to be a minor toxic, it affects the taste and odour of water at concentrations of < 30 microg/L. Although MTBE is often a recalcitrant compound, it is known that many ethers can be degraded by abiotic means. The aim of this study was to examine biotic and abiotic transformations of MTBE with respect to the particular conditions of a contaminated site (former refinery) in Leuna, Germany. Groundwater samples from wells of a contaminated site were used for aerobic and anaerobic degradation experiments. The abiotic degradation experiment (hydrolysis) was conducted employing an ion-exchange resin and MTBE solutions in distilled water. MTBE, tertiary butyl formate (TBF) and tertiary butyl alcohol (TBA) were measured by a gas chromatograph with flame ionisation detector (FID). Aldehydes and organic acids were respectively analysed by a gas chromatograph with electron capture detector (ECD) and high-performance ion chromatography (HPIC). Under aerobic conditions, MTBE was degraded in laboratory experiments. Only 4 of a total of 30 anaerobic experiments exhibited degradation, and the process was very slow. In no cases were metabolites detected, but a few degradation products (TBF, TBA and formic acid) were found on the site, possibly due to the lower temperatures in groundwater. The abiotic degradation of MTBE with an ion-exchange resin as a catalyst at pH 3.5 was much faster than hydrolysis in diluted hydrochloric acid (pH 1.0). Although the aerobic degradation of MTBE in the environment seems to be possible, the specific conditions responsible are widely unknown. Successful aerobic degradation only seems to take place if there is a lack of other utilisable compounds. However, MTBE is often accompanied by other fuel compounds on contaminated sites and anaerobic conditions prevail. MTBE is often recalcitrant under anaerobic conditions, at least in the presence of other carbon sources. The abiotic hydrolysis of MTBE seems to be of secondary importance (on site), but it might be possible to enhance it with catalysts. MTBE only seems to be recalcitrant under particular conditions. In some cases, the degradation of MTBE on contaminated sites could be supported by oxygen. Enhanced hydrolysis could also be an alternative.

Photodegradation of methyl tertiary butyl ether (MTBE) vapor with immobilized titanium dioxide

A study on the photocatalytic degradation of methyl tertiary butyl ether (MTBE) vapor was performed with respect to reaction parameters, kinetics, and mechanism. A conventional TiO2-coated plate system was used for this initial work on vaporized MTBE. On irradiating with UVBLB (∼5 mW/cm2), 0.6 mg/cm2 of TiO2 (P25) photocatalyst showed the highest reaction rate (0.85 μmol/min) for 25.76 μmole of MTBE (1000 ppmv). The numerical values obtained depended predictably with respect to light intensity, initial concentration, and quantity of P25. The photocatalytic degradation of MTBE followed Lanmuir-Hinshelwood kinetics with a linearity of 0.989. As far as the mechanism of degradation is concerned, attack by generated hydroxyl radicals on the methoxy group in the MTBE structure dominated and proceeded through tert-butyl formate (TBF) as an intermediate, instead of methyl group to proceed through producing 2-methoxy-2-methyl propionaldehyde (MMP). TBF finally degrades to CO2 through acetone, which was shown easily converted to CO2. This study shows that the use of sunlight seems to be possible given adequate tools for concentrating the light.

Non-Significance of Rhizosphere Degradation During Phytoremediation of MTBE

Abstract Methyl tertiary butyl ether (MTBE) is a gasoline additive associated with ground water pollution at gas station sites. Previous research on poplar trees in hydroponic systems suggests that phytovolatilization is an effective mechanism for phytoremediation of MTBE (Rubin and Ramaswami, 2001), but the potential for microbial degradation of MTBE in the rhizosphere of trees had not been assessed. MTBE had largely been considered recalcitrant to microbial processes, but recent field‐work suggests rapid biodegradation may occur in certain cases. This paper investigates the potential for rhizosphere degradation of MTBE at time frames relevant for phytoremediation. Three experiments were conducted at different levels of aggregation to examine possible degradation of MTBE by rhizosphere microorganisms that had been acclimated to low levels of MTBE for 6 weeks. MTBE soil die‐away studies, conducted with both poplar trees and fescue grass, found no significant differences between MTBE concentration in vegetated and unvegetated soils over a two‐week attenuation period. Closed chamber tests comparing hydroponic and rhizospheric poplar tree systems also showed essentially complete recovery of MTBE mass in both systems, suggesting an absence of degradation. Finally, rhizosphere microbes tested in aerated bioreactors were found to be thriving and metabolizing root materials, but did not show measurable degradation of MTBE. In all tests, the MTBE degradation product, Tert Butyl Alcohol (TBA), was not detected. The insignificance of MTBE degradation by rhizosphere microorganisms suggests that plant processes be the primary focus of further research on MTBE phytoremediation.

The photocatalytic oxidation of low concentration MTBE on titanium dioxide from groundwater in a falling film reactor

AbstractThis study is focused on three main objectives: (1) to determine the feasibility of using a falling‐film slurry photocatalytic reactor for the degradation of methyl tertiary‐butyl ether (MTBE) in water, (2) to assess the feasibility of MTBE photo‐oxidation on TiO2 at low initial MTBE concentrations (&lt; 1 mg/L), and (3) to compare the effectiveness of MTBE photo‐oxidation on TiO2 in synthetically‐contaminated water, and in actual MTBE‐contaminated groundwater samples.The MTBE degradation rates observed in a laminar falling film photocatalytic reactor for synthetic samples, with concentrations ranging from 50 μg/L to 1 mg/L, were high, achieving nearly complete (99+%) degradation of 1 mg/L MTBE and its by products in less than 120 minutes. The calculated single‐pass conversions were as high as 60%, corresponding to residence times of approximately 5 seconds in the falling film reactor. The observed degradation products of MTBE oxidation were predominantly tert‐butyl alcohol (TBA) and tertbutyl formate (TBF).However, tests conducted using groundwater samples showed significantly reduced photoactivity of TiO2 towards the degradation of MTBE. Aromatic species and dissolved metal and chloride ions present in the field samples compete with MTBE and molecular oxygen on the TiO2 surface, and hence delay and retard MTBE degradation.

Non‐significance of rhizosphere degradation during phytoremediation of MTBE

Methyl tertiary butyl ether (MTBE) is a gasoline additive associated with ground water pollution at gas station sites. Previous research on poplar trees in hydroponic systems suggests that phytovolatilization is an effective mechanism for phytoremediation of MTBE (Rubin and Ramaswami, 2001), but the potential for microbial degradation of MTBE in the rhizosphere of trees had not been assessed. MTBE had largely been considered recalcitrant to microbial processes, but recent field‐work suggests rapid biodegradation may occur in certain cases. This paper investigates the potential for rhizosphere degradation of MTBE at time frames relevant for phytoremediation. Three experiments were conducted at different levels of aggregation to examine possible degradation of MTBE by rhizosphere microorganisms that had been acclimated to low levels of MTBE for 6 weeks. MTBE soil die‐away studies, conducted with both poplar trees and fescue grass, found no significant differences between MTBE concentration in vegetated and unvegetated soils over a two‐week attenuation period. Closed chamber tests comparing hydroponic and rhizospheric poplar tree systems also showed essentially complete recovery of MTBE mass in both systems, suggesting an absence of degradation. Finally, rhizosphere microbes tested in aerated bioreactors were found to be thriving and metabolizing root materials, but did not show measurable degradation of MTBE. In all tests, the MTBE degradation product, Tert Butyl Alcohol (TBA), was not detected. The insignificance of MTBE degradation by rhizosphere microorganisms suggests that plant processes be the primary focus of further research on MTBE phytoremediation.

Biodegradation of methyl tertiary butyl ether (MTBE) by a bacterial enrichment consortia and its monoculture isolates

Methyl tertiary butyl ether (MTBE), an important gasoline additive, is a recalcitrant compound posing serious environmental health problems. In this study, MTBE-degrading bacteria were enriched from five environmental samples. Enrichments from Stewart Lake sediments and an MTBE contaminated soil displayed the highest rate of MTBE removal; 29.6 and 27.8% respectively, in 28 days. A total of 12 bacterial monocultures isolated from enrichment cultures were screened for MTBE degradation in liquid cultures. In a nutrient-limited medium containing MTBE as the sole source of carbon and energy, the highest rate of MTBE elimination was achieved with IsoSL1, which degraded 30.6 and 50.2% in 14 and 28 days, respectively. In a nutrient-rich medium containing ethanol and yeast extract, the bacterium (Iso2A) substantially removed MTBE (20.3 and 28.1% removal in 14 and 28 days, respectively). Based upon analysis of the 16s rRNA gene sequence and data base comparison, IsoSL1 and Iso2A were identified as a Streptomyces sp. and Sphingomonas sp., respectively. The Streptomyces sp. is a new genera of bacteria degrading MTBE and could be useful for MTBE bioremediation.

The Effective Increase of Aquasonolysis of Methyl Tertiary Butyl Ether

Methyl tertiary butyl ether (MTBE) is one of the most commonly used fuel oxygenates. In principle, the degradation of organic compounds by ultrasound in water (aquasonolysis), in combination with oxidizing agents represents an advanced technology for remediation of waters, which are contaminated with MTBE. For the combination of ultrasound with ozone, enhancement factors of 2.0 (MTBE), 1.5 (ETBE) and 2.1 (TAME) were found and measurable synergistic effects could be detected. Studying the sonolysis of an aqueous fuel mixture (ARAL, SuperPlus), the increase in effectiveness of the aquasonolysis was lower than that for the individual substances. This result can be attributed to a higher initial concentration of the educts. A possible reaction mechanism is given for the products of the sonochemical degradation of MTBE in presence of ozone and hydrogen peroxide.