Degradation of gasoline oxygenates in the subsurface

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dc.contributor.authorYeh, Kuei-Jyumen
dc.contributor.committeechairNovak, Johnen
dc.contributor.committeememberRandall, Clifford W.en
dc.contributor.committeememberBerry, Duane F.en
dc.contributor.committeememberBenoit, Robert E.en
dc.contributor.committeememberGoldsmith, C. Douglasen
dc.contributor.departmentCivil Engineeringen
dc.date.accessioned2014-03-14T21:14:40Zen
dc.date.adate2008-06-06en
dc.date.available2014-03-14T21:14:40Zen
dc.date.issued1992en
dc.date.rdate2008-06-06en
dc.date.sdate2008-06-06en
dc.description.abstractTertiary butyl alcohol (TBA), methyl tertiary butyl ether (MTBE) and ethyl tertiary butyl ether (ETBE) are compounds with the potential for use as oxygenates in reformulated gasolines. Being relatively soluble in water, these organics, if accidentally discharged into the subsurface, may rapidly spread and pose threats to groundwater. The purpose of this work was to evaluate the biodegradation potential of these oxygenates in soils and to determine the influence of subsurface environments on their degradation. Biodegradation was evaluated in static soil/water microcosms. Aquifer material was collected from various depths at three sites with different soil characteristics. Potential electron acceptors including O₂ in the form of H₂O₂, nitrate or sulfate were added to induce the desired metabolism (aerobic respiration, denitrification, sulfate reduction, or methanogenesis). In each metabolic process, the influence of several subsurface environmental factors on biodegradation was investigated. The data show that biodegradation potential of MTBE, ETBE and TBA varied substantially with site and depth. TBA was the easiest compound to biodegrade, whereas MTBE was the most recalcitrant. Cleavage of the ether bond is the first and rate-limiting step in the degradation of ETBE and possibly MTBE. Addition of H₂O₂, caused chemical oxidation of MTBE and ETBE. The chemical oxidation was faster in the organically rich soils, but slower in the organic-poor soils. Soil microorganisms were able to catalyze the cleavage of the ether bond in ETBE but not MTBE. This biological reaction was not significant when chemical oxidation occurred. TBA, on the other hand, was aerobically biodegraded in all soils. Under denitrifying and anaerobic conditions TBA degradation occurred in all soils but the degradation of ETBE and MTBE was only observed at one of three sites. TBA degradation was enhanced by nutrient addition in the nutrient-poor soil but hindered by the presence of other easily-degraded organic compounds. Degradation of MTBE and ETBE occurred only in soils containing low organic matter with a pH around 5.5. No degradation of MTBE and ETBE was observed in the organic-rich soils and in the organically poor soils, the addition of ethanol inhibited MTBE and ETBE degradation.en
dc.description.degreePh. D.en
dc.format.extentxi, 221 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-06062008-172029en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-06062008-172029/en
dc.identifier.urihttp://hdl.handle.net/10919/38510en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V856_1992.Y43.pdfen
dc.relation.isformatofOCLC# 26091130en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V856 1992.Y43en
dc.subject.lcshButanol -- Biodegradationen
dc.subject.lcshButyl methyl ether -- Biodegradationen
dc.subject.lcshEther -- Biodegradationen
dc.titleDegradation of gasoline oxygenates in the subsurfaceen
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplineCivil Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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