Biodegradation and Bioconcentration of Alkyl Ethers

Abstract

Tertiary-butyl methyl ether (MTBE) has recently attracted much attention as a high-octane blending stock in the preparation of unleaded premium gasoline.The biodegradation study of several alkyl ethers having various alkyl groups was carried out by measuring the oxygen uptake rate in the presence of standard activated sludge as a source of microorganisms. Although alkyl ethers with t-butyl groups in their molecules showed very poor biodegradability (Fig.-1), MTBE had no effect on the biodegradability of gasoline blended with it (Fig.-2). MTBE-blended gasoline was found to have excellent biodegradability and causes no environmental pollution.The bioconcentration factor in fish was determined by the cultivation of Japanese carp in a flowing water system containing alkyl ethers over a period of four weeks. Alkyl ethers used in this bioconcentration experiment were 2- (t-butoxy) ethanol, MTBE, and t-butyl isopropyl ether. The bioconcentration factors of these ethers were 0.6, 1.5, and 5.7, respectively (Fig.-3, Table-1 and Table-2). The concentrated MTBE in the fish was excluded quite rapidly on placing the fish in fresh water (Fig.-3). The bioconcentration factors of water-soluble chemicals such as the alkyl ethers used in this experiment, can be predicted from their partition coefficients in an 1-octanol-water system (Fig.-4).