Methyl Tertiary Butyl Ether Removal Research Articles

Removal and Recovery of Methyl Tertiary Butyl Ether (MTBE) from Water Using Carbon Nanotube and Graphene Oxide Immobilized Membranes.

Methyl tert-butyl ether (MTBE) is a widely used gasoline additive that has high water solubility, and is difficult to separate from contaminated ground and surface waters. We present the development in functionalized carbon nanotube-immobilized membranes (CNIM-f) and graphene oxide-immobilized membranes (GOIM) for enhanced separation of MTBE via sweep gas membrane distillation (SGMD). Both types of modified membranes demonstrated high performance in MTBE removal from its aqueous mixture. Among the membranes studied, CNIM-f provided the best performance in terms of flux, removal efficiency, mass transfer coefficients and overall selectivity. The immobilization f-CNTs and GO altered the surface characteristics of the membrane and enhanced partition coefficients, and thus assisted MTBE transport across the membrane. The MTBE flux reached as high as 1.4 kg/m2 h with f-CNTs, which was 22% higher than that of the unmodified PTFE membrane. The maximum MTBE removal using CNIM-f reached 56% at 0.5 wt % of the MTBE in water, and at a temperature of 30 °C. With selectivity as high as 60, MTBE recovery from contaminated water is very viable using these nanocarbon-immobilized membranes.

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.

Biodegradation of Methyl Tertiary Butyl Ether (MTBE) by a Microbial Consortium in a Continuous Up-Flow Packed-Bed Biofilm Reactor: Kinetic Study, Metabolite Identification and Toxicity Bioassays.

This study investigated the aerobic biodegradation of methyl tertiary-butyl ether (MTBE) by a microbial consortium in a continuous up-flow packed-bed biofilm reactor using tezontle stone particles as a supporting material for the biofilm. Although MTBE is toxic for microbial communities, the microbial consortium used here was able to resist MTBE loading rates up to 128.3 mg L-1 h-1, with removal efficiencies of MTBE and chemical oxygen demand (COD) higher than 90%. A linear relationship was observed between the MTBE loading rate and the MTBE removal rate, as well as between the COD loading rate and the COD removal rate, within the interval of MTBE loading rates from 11.98 to 183.71 mg L-1 h-1. The metabolic intermediate tertiary butyl alcohol (TBA) was not detected in the effluent during all reactor runs, and the intermediate 2-hydroxy butyric acid (2-HIBA) was only detected at MTBE loading rates higher than 128.3 mg L-1 h-1. The results of toxicity bioassays with organisms from two different trophic levels revealed that the toxicity of the influent was significantly reduced after treatment in the packed-bed reactor. The packed-bed reactor system used in this study was highly effective for the continuous biodegradation of MTBE and is therefore a promising alternative for detoxifying MTBE-laden wastewater and groundwater.

Investigating the removal of methyl tertiary butyl ether (MTBE) from water using raw and modified fly ash waste materials

Classical techniques for remediation of methyl tertiary butyl ether (MTBE) from contaminated water sources are characterized by inherent limitations due to its unique physical and chemical characteristics, making further remediation researches promising. Fly ash (FA), which is a waste material derived from the combustion of coal or heavy liquid fuel has been reported to show favorable adsorption results with selected metals, dyes, and some organics in aqueous solution. In this study, raw FA, acid-treated FA, and metal oxide (silver, iron, and aluminum) impregnated FA were assessed on a bench scale, for MTBE adsorption in contaminated water system and benchmarked against activated carbon (AC). Results showed that only silver oxide (Ag2O) impregnated FA achieved ~24% removal of MTBE from aqueous solution, while the other tested adsorbent materials achieved <10%. MTBE optimum adsorption was attained after 120 min of contact, and 0.5 g/L dosage of adsorbent. Conversely, silver oxide impregnation of AC brought about a drop in its MTBE removal efficiency from an optimum efficiency of 71 to 53%. Also, the Langmuir isotherm model best represented the MTBE adsorption behavior of both the Ag2O-impregnated FA and AC, having R2 of 88.75–89.92%, respectively.

Removal of MTBE from aqueous solution using natural nanoclays of Iran

In the present study, the adsorption capability of methyl tertiary butyl ether (MTBE) was investigated using natural nanoclays of Iran including perlite, dolomite, diatomite, and perlite/diatomite/dolomite composite. The physicochemical properties of natural clays were determined using dynamic light scattering, scanning electron microscope, Fourier Transform Inferred, X-ray fluorescence, and Brunauer–Emmet–Teller analysis. The effect of sorption parameters including contact time, initial concentration, and temperature on the MTBE removal was evaluated in a batch system. The maximum monolayer sorption capacity of nanoclays for MTBE sorption was found to be in order of: diatomite (143.19 mg g−1) > perlite/diatomite/dolomite (133.12 mg g−1) > dolomite (103.18 mg g−1) > perlite (93.13 mg g−1). The kinetic data were analyzed using pseudo-first-order and pseudo-second-order model. Freundlich, Langmuir, and Dubinin–Radushkevich isotherm models were used to describe the equilibrium data of MTBE sorption. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) indicated that the MTBE sorption using studied nanoclays was spontaneous and endothermic. The results showed that nanoclay samples due to low cost and high efficiency can be used extensively for the removal of MTBE from water in industry.

A comparative study of removal of methyl tertiary-butyl ether (MTBE) from aquatic environments through advanced oxidation methods of H2O2/nZVI, H2O2/nZVI/ultrasound, and H2O2/nZVI/UV

This study compares the efficiency of oxidation with H2O2 and nanoscale zero-valent iron (nZVI)in the presence of ultrasound and that of oxidation with ultraviolet radiation and H2O2/nZVI in the removal of MTBE from aqueous solutions. The effects of some parameters, such as ultrasound, contact time (2–60 min), concentration of hydrogen peroxide (5–20 ml/L), concentrations of nZVI (0.15–0.45 g/L), pH (2–9), and concentration of MTBE (50–750 mg/L) were investigated. In this study, the best MTBE removal efficiency was obtained at a rate of 89.56% in a concentration of 50 mg/Lat pH 3.5 with optimal H2O2 concentration of 10 ml/L, nZVI concentration of 0.25 g/L, and oxidation time of 15 min. Comparison of the effects of ultrasound with those of ultraviolet radiation, in similar conditions, showed no significant difference in efficiency between the ultrasound and UV (p ˃ 0.05). However, comparing the efficiency of oxidation in the presence of ultrasound and without ultrasound in similar oxidation conditions showed significant differences (p ˂ 0.05). In optimum conditions for oxidation, H2O2/nZVI/ultrasonic can be used as a convenient and efficient method to reduce concentration of MTBE in contaminated waters.

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 contaminated water using UV-assisted nano composite materials

This study was designed to examine the efficacy of UV-assisted nano material treatments to remove methyl tertiary butyl ether (MTBE) from contaminated water. The focus was to investigate the applicability of combining the degradation potential of nano TiO2 photocatalysis and adsorption power of carbon nano tubes (CNTs). Effect of different combinations of two ultraviolet radiations (UVA and UVC) and three types of nano materials: TiO2, CNTs, and TiO2/CNTs on MTBE remediation was studied. Removal efficiency of different combinations varied significantly with highest removal (95%) achieved by UVC-TiO2, followed by UVC-CNTs (75%) and UVA-TiO2/CNTS (60%). However, additive effect of UV/TiO2/CNTs on MTBE removal from water was not observed. Major degradation byproducts formed were acetone, tertiary butyl formate, and tertiary butyl alcohol.

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.

Experimental and Theoretical Study of MTBE Adsorption from Polluted Water on GAC and PAC in Continuous Process

Methyl tertiary butyl ether (MTBE) is an organic compound thatis used to increase the gasoline octane number. At the beginning of 1980s, by discovering the undesirable effects of tetra ethyl lead usage in fuel, MTBE began to be used worldwide. But gradually the undesirable effects of MTBE on environment had been revealed. Adsorption is the most conventional and economical technology for MTBE removal from polluted water. In this research, some experiments have been done for studying the adsorption of MTBE on different solid adsorbent in continuous processes. In continuous experiments, the water polluted with known initial MTBE concentration passes through an adsorption column containing two kinds of adsorbent including granular activated carbon (GAC), powdered activated carbon (PAC). By measuring MTBE concentration in exit flow at different times the effect of different operating parameters such as temperature, pH, and flow rate have been studied and the optimum condition have been determined. The batch experimental results have been used to calculate the constant parameters of Langmuir adsorption isotherm equations. A dynamic simulation of MTBE adsorption on activated carbon in an adsorption column has been proposed. The comparison of the experimental data with the values given by the proposed model for similar operating conditions, verifies the accuracy of the proposed mathematical model.

Adsorption of Methyl Tertiary Butyl Ether and Trichloroethylene in MFI-Type Zeolites

We used Monte Carlo simulations to understand how the Si/Al ratio of MFI-type zeolites affects their adsorption performance in the removal of VOCs from water. We considered adsorption of methyl tertiary butyl ether (MTBE) and trichloroethylene (TCE) to zeolites because they have different interactions with water, with MTBE being hydrophilic and TCE being hydrophobic. We carried out adsorption simulation in MFI-type zeolites of three different Si/Al ratios (∞, 191, and 95). Our results showed that because MTBE molecules can adsorb only to the channel intersection, the presence of Al sites close to the intersections would promote water clustering and prevent the access of MTBE molecules to these sites. However, if the hydrophilic sites are far from the intersections, MTBE adsorption capacity is less impeded. Therefore, the distribution of Al sites in ZSM-5 zeolites is also an important factor determining the MTBE removal efficiency of these materials. The reduction in TCE removal capacity of the zeolites du...

Field Treatment of MTBE‐Contaminated Groundwater Using Ozone/UV Oxidation

Methyl‐tertiary butyl ether (MTBE) is often found in groundwater as a result of gasoline spills and leaking underground storage tanks. An extrapolation of occurrence data in 2008 estimated at least one detection of MTBE in approximately 165 small and large public water systems serving 896,000 people nationally (United States Environmental Protection Agency [U.S. EPA] 2008). The objective of this collaborative field study was to evaluate a small groundwater treatment system to determine the effectiveness of ultraviolet (UV)/ozone treatment in removing MTBE from contaminated drinking water wells. A pilot‐scale advanced oxidation process (AOP) system was tested to evaluate the oxidation efficiency of MTBE and intermediates under field conditions. This system used ozone as an oxidizer in the presence of UV light at hydraulic retention times varying from 1 to 3 min. MTBE removal efficiencies approaching 97% were possible with this system, even with low retention times. The intermediate t‐butyl alcohol (TBA) was removed to a lesser extent (71%) under the same test conditions. The main intermediate formed in the oxidation process of the contaminated groundwater in these studies was acetone. The concentrations of the other anticipated intermediates t‐butyl formate (TBF), isopropyl alcohol (IPA), methyl acetate (MAc), and possible co‐occurring aromatics (BTEX) in the effluent were negligible.

Evaluation of UV/O 3 process for removal of methyl tertiary-butyl ether in aqueous solutions

Aims: In the present investigation, the methyl tertiary-butyl ether (MTBE) removal efficiency from the synthetic solutions by the means of advanced oxidation process of UV/O 3 was studied. Materials and Methods: To study the efficiency of process, the following variables were studied: ozone concentration, pH, MTBE initial concentration, and radiation duration. As The radiation source, a Mercury vapor UV lamp with moderate pressure (400W) was used which was immersed vertically in the solution containing MTBE, in a glass reactor (Volume: 2 L). Results: The results showed that the efficiency of UV radiation and ozone alone in 50 mg/L concentration and pH: 7 on MTBE removal was 4 and 53%, respectively. The UV/O 3 compound process removal efficiency in 60 minutes was 63%. The pH played a significant role in the process, as with the increase in pH, the removal rate increased as well. The removal rates for the initial concentrations of 10, 20, 50, and 100 mg/L of MTBE were 98, 81.5, 72.8, and 63.8%, respectively. Conclusion: The results of the present survey indicated that the efficiency of the UV/O 3 combination process was more than ultraviolet (UV) and Ozone alone. In the UV/O 3 combination process, the MTBE removal efficiency increased as the O 3 concentration and pH increased, while the efficiency decreased as the MTBE concentration decreased.

Removal of methyl tertiary-butyl ether (MTBE) from water by polymer–zeolite composites

Methyl tertiary-butyl ether (MTBE), a semi volatile organic compound used as a gasoline additive, has been extensively detected in surface and groundwater and therefore became a major issue as an environmental pollutant. The removal of methyl tertiary-butyl ether (MTBE) from water by high-silica zeolite, high-silica zeolite composites, and by granular activated carbon (GAC) was investigated in suspension and by filtration. The Langmuir model yielded good simulation and prediction of MTBE removal. The removal of MTBE from water was more efficient by composites of polyacrylamide (PAM)-zeolite designed in this study than by untreated zeolite or GAC. Even in the presence of BTEX (benzene, toluene, ethyl-benzene and xylene) MTBE removal was very efficient by the PAM-zeolite composites, in comparison to its removal by the zeolite or GAC, reaching 2.5- and 75-fold higher removal, respectively. Filtration of MTBE solution through columns filled with GAC mixed with a PAM-zeolite composite (5:1 w/w ratio) demonstrated several-fold enhanced removal relative to a control which included only GAC. We suggest that the enhanced removal by the PAM-zeolite composite is attributed to (a) the displacement of water from the zeolite surface upon PAM adsorption, which promotes MTBE adsorption and (b) hydrogen binding between the polymer and MTBE.

The impact of groundwater quality on the removal of methyl tertiary-butyl ether (MTBE) using advanced oxidation technology

In this study, the removal of methyl tertiary-butyl ether (MTBE) from contaminated groundwater using advanced oxidation technology was investigated. The UV/H(2)O(2) treatment process was applied to remove MTBE from two Saudi groundwater sources that have different quality characteristics with regard to their contents of inorganic species such as chloride, bromide, sulfates and alkalinity. MTBE was spiked into water samples collected from the two sources to a concentration level of about 250 microg/L. A 500 mL bench-scale forced-liquid circulation photoreactor was used to conduct the experiments. Two different UV lamps were utilized: 15 Watt low pressure (LP) and 150 Watt medium pressure (MP). Results of the study showed that the UV/H(2)O(2) process removed more than 90% of MTBE in 20 minutes when the MP lamp was used at an MTBE/H(2)O(2) molar ratio of 1:200. The results also showed that groundwater sources with higher levels of radical scavengers such as alkalinity, bromide, nitrate and sulfate showed lower rate of MTBE removal.

MTBE adsorption on alternative adsorbents and packed bed adsorber performance

Widespread use of the fuel additive methyl tertiary-butyl ether (MTBE) has led to frequent MTBE detections in North American and European drinking water sources. The overall objective of this research was to evaluate the effectiveness of a silicalite zeolite, a carbonaceous resin, and a coconut-shell-based granular activated carbon (GAC) for the removal of MTBE from water. Isotherm and short bed adsorber tests were conducted in ultrapure water and river water to obtain parameters describing MTBE adsorption equilibria and kinetics and to quantify the effect of natural organic matter (NOM) on MTBE adsorption. Both the silicalite zeolite and the carbonaceous resin exhibited larger MTBE adsorption uptakes than the tested GAC. Surface diffusion coefficients describing intraparticle MTBE mass transfer rates were largest for the GAC and smallest for the carbonaceous resin. Pilot tests were conducted to verify MTBE breakthrough curve predictions obtained with the homogeneous surface diffusion model and to evaluate the effect of NOM preloading on packed bed adsorber performance. Results showed that GAC was the most cost-competitive adsorbent when considering adsorbent usage rate only; however, the useful life of an adsorber containing silicalite zeolite was predicted to be ∼5–6 times longer than that of an equally sized adsorber containing GAC. Pilot column results also showed that NOM preloading did not impair the MTBE removal efficiency of the silicalite zeolite. Thus, it may be possible to regenerate spent silicalite with less energy-intensive methods than those required to regenerate GAC.

Biodegradation kinetics and microbial communities associated with methyl tert-butyl ether removal in a biotrickling filter

A microbial culture capable of degrading methyl tertiary butyl ether (MTBE) was enriched in a laboratory-scale biotrickling filter. The reactor was continuously operated in a temperature-controlled condition for more than 100 days. Removal of MTBE vapors from air streams in a biotrickling filter was studied under various operating conditions, including the MTBE loading rate and the type of media in the circulating liquid. The changes in an MTBE-degrading bacterial community were investigated by using polymerase chain reaction (PCR) amplification of bacterial 16S rDNA. A subsequent analysis of the PCR products was performed by a single-strand-conformation polymorphism (SSCP) based on genetic profiles. Our results show that the MTBE removal efficiencies of 98.6–57.3% were observed at the MTBE loading rates of 2.67–50.76 g m −3 h −1 in the biotrickling filter. The removal efficiency appeared to increase by 27% (from 68 to 95%) in a later phase operation when the nitrogen source of (NH 4 ) 2 SO 4 was replaced by NaNO 3 . Due to the high MTBE loads in the inlet section, MTBE was removed mostly from the inlet section. The parameters estimated by using the Michaelis–Menten equation were 1.607 ± 0.208 ppmv s −1 for the maximum removal rate ( V m ), and 24.91 ± 0.794 ppmv for the half-saturation constant ( K s ). The total number of bands in an electrophoresis gel for various sections in the biotrickling filter using the same nitrogen source was similar, thus indicating similar compositions of species in the biotrickling filter. Nevertheless, communities grown in the presence of (NH 4 ) 2 SO 4 and NaNO 3 media exhibited a very different pattern, thus revealing a small change in community structure due to the type of media.

Comparison of Biostimulation versus Bioaugmentation with Bacterial Strain PM1 for Treatment of Groundwater Contaminated with Methyl Tertiary Butyl Ether (MTBE)

Widespread contamination of groundwater by methyl tertiary butyl ether (MTBE) has triggered the exploration of different technologies for in situ removal of the pollutant, including biostimulation of naturally occurring microbial communities or bioaugmentation with specific microbial strains known to biodegrade the oxygenate. After laboratory studies revealed that bacterial strain PM1 rapidly and completely biodegraded MTBE in groundwater sediments, the organism was tested in an in situ field study at Port Hueneme Naval Construction Battalion Center in Oxnard, California. Two pilot test plots (A and B) in groundwater located down-gradient from an MTBE source were intermittently sparged with pure oxygen. Plot B was also inoculated with strain PM1. MTBE concentrations up-gradient from plots A and B initially varied temporally from 1.5 to 6 mg MTBE/L. Six months after treatment began, MTBE concentrations in monitoring wells down-gradient from the injection bed decreased substantially in the shallow zone of the ground-water in plots A and B, thus even in the absence of the inoculated strain PM1. In the deeper zone, downstream MTBE concentrations also decreased in plot A and to a lesser extent in plot B. Difficulties in delivery of oxygen to the deeper zone of plot B, evidenced by low dissolved oxygen concentrations, were likely responsible for low rates of MTBE removal at that location. We measured the survival and movement of strain PM1 in groundwater samples using two methods for detection of DNA sequences specific to strain PM1: TaqMan quantitative polymerase chain reaction, and internal transcribed spacer region analysis. A naturally occurring bacterial strain with > 99% 16S rDNA sequence similarity to strain PM1 was detected in groundwater collected at various locations at Port Hueneme, including outside the plots where the organism was inoculated. Addition of oxygen to naturally occurring microbial populations was sufficient to stimulate MTBE removal at this site. In some cases, however, inoculation with an MTBE-degrading culture may be warranted.

Remediation of MTBE from Drinking Water: Air Stripping Followed by Off-Gas Adsorption

The widespread use of methyl tertiary butyl ether (MTBE) as an oxygenate in gasoline has resulted in the contamination of a large number of ground and surface water sources. Even though air stripping has been proven to be an effective treatment technology for MTBE removal, off-gas treatment often is required in conjunction with it. This study evaluated the combined treatment technologies of air stripping followed by off-gas adsorption on a pilot scale for the treatment of MTBE-contaminated water. The effect of air/water ratios on the treatment efficiency was studied, and the mass transfer coefficient was determined. Air/water ratios of 105:1, 151:1, 177:1, 190:1, 202:1, and 206:1 were used, and a treatment efficiency of >99% was achieved for all the runs conducted. The depth of packing required to achieve maximum treatment efficiency decreased with increasing air/water ratio. Relative humidity (RH) impacts on the MTBE adsorption capacity of a granular activated carbon (GAC) and carbonaceous resin were determined from pilot plant studies. Breakthrough profiles obtained from the pilot plant studies conducted at 20, 30, and 50% RH indicated that GAC has a higher adsorptive capacity than resin. The adsorptive capacity of GAC decreased with increasing RH, whereas RH did not impact the resin adsorptive capacity.

Bioremediation of methyl tertiary-butyl ether (MTBE) by an innovative biofilter

Methyl tertiary-butyl ether (MTBE) is a synthetic chemical used in unleaded gasoline as an additive to reduce levels of ozone and carbon monoxide from auto exhaust. Due to its chemical and recalcitrant properties, MTBE has caused groundwater contamination worldwide. A laboratory-scale biofilter made of a natural fiber (kenaf) mat and inoculated with MTBE-degrading microorganisms, was evaluated for MTBE removal efficiency. Operational parameters of oxygen flow rate, hydraulic retention time (HRT), yeast extract and initial MTBE concentration were varied and MTBE removal efficiencies determined. Four kinetic models were evaluated to describe the MTBE removal in the reactor. Formaldehyde and tertiary butyl alcohol (the most two reported MTBE biodegradation byproducts) were not found in the effluent; instead, carbon dioxide was monitored as the end product based on the results of a metabolic mass balance evaluation. Toxicity of treated effluent was evaluated by employing the Microtox acute toxicity test and comparing that to the influent.