Date of Award

6-2007

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Systems Engineering and Management

First Advisor

Charles A. Bleckmann, PhD

Abstract

Methyl tert-Butyl Ether (MTBE) is the most commonly used fuel oxygenate in the world. Its recalcitrant nature as well as its chemical properties have led to widespread groundwater contamination. Questions regarding its toxicity have spurred a search for viable oxygenate alternatives. Since biodegradability is a key indicator of a chemical’s environmental impact, this research used three different well-known methods, BOD5, respirometry, and GC analysis, to examine the extent and rates of aerobic biodegradation of MTBE along with tert-butyl alcohol (TBA). The common fuel component toluene was added to some of the samples to determine if the presence of a co-contaminant would effect aerobic microbial degradation of TBA or MTBE. This group of experiments used an acclimatized microbial consortium to enhance degradation of the oxygenates. BOD5 experiments were performed separately from the GC and respirometric analyses. The respirometry used 250ml microcosms containing a mix of microbial seed, BOD buffer, and varying concentrations of the oxygenates or oxygenate/toluene mixtures. The respirometer also maintained the microcosms in aerobic conditions for the duration of each experiment. For GC analysis, samples were drawn from the respirometer microcosms at predetermined intervals and first order degradation rate constants were calculated from established calibration curves. The oxygenates degraded much slower than toluene in all experiments. This degradation characteristic made BOD5 analysis impractical for MTBE or TBA. BOD5 did provide valid results for toluene. The respirometer data was not as good as gas chromatography to provide specific measurements of degradation. To facilitate comparison of degradation across experiments with differing seed, oxygenate degradation was compared to toluene. MTBE was effectively degraded under these experimental conditions and degraded at 13.94% the rate of toluene. TBA was more recalcitrant and only degraded at 1.37% of toluene.

AFIT Designator

AFIT-GES-ENV-07-J1

DTIC Accession Number

ADA469812

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