Biological degradation of methyl tertiary-butyl ether (MTBE) oxidation byproducts

“An integrated chemical/biological (ICB) process was examined for removing methyl tertiary-butyl ether (MTBE) from solution. UV/H2O2 oxidation was used to oxidize MTBE forming acetone, methyl acetate, formic acid, tertiary-butyl alcohol (TBA), and tertiary-butyl formate (TBF) as the major byproducts. Biological degradation studies indicated that acetone and methyl acetate were readily degradable while MTBE, TBA, and TBF were biologically recalcitrant to the cultures used during this research. Removal rates for the degradable byproducts were determined using a native mixed culture (municipal treatment plant return activated sludge) and an enhanced culture. The native mixed culture degraded acetone and methyl acetate at average rates of 0.0163 ± 0.0033 mg L-1 min-1 and 0.0349 ± 0.0079 mg L-1 min-1 respectively while the enhanced culture degraded them at rates of 0.0601 ± 0.0360 mg L-1 min-1 and 0.2510 ± 0.1210 mg L-1 min-1 respectively. Monod kinetic constants were determined for acetone and methyl acetate degradation by both the mixed and enhanced cultures. The availability of multiple carbon sources and the presence of excess H2O2 during acetone and methyl acetate biodegradation were also examined. Methyl acetate removal was not significantly affected by the presence of other compounds, while acetone removal was slowed considerably. The presence of H2O2 appeared to enhance biological removal at low concentrations, 10-30 mg L-1, and appeared to inhibit it at higher concentrations, 100-300 mg L-1. The production of biodegradable compounds from the oxidation of MTBE supports the possibility of an integrated chemical/biological process to remove MTBE from contaminated groundwater”--Abstract, page iii