The biodegradability of various biodiesel fuels was examined by the CO{sub}2 evolution method(EPA 560/6-82-003), BOD{sub}5 (EPA 405.1), COD (EPA 410), and gas chromatography (GC)analyses in an aquatic system. The fuels examined included the methyl- and ethyl-esters of rapeseedoil and soybean oil, neat rapeseed oil. neat soybean oil and Phillips 2-D low sulfur; referencepetroleum diesel. Blends of biodiesel/petroleum diesel at different volumetric ratios, including 80/20,50/50, and 20/80, were also examined. The results demonstrate that all the biodiesel fuels are "readilybiodegradable". Moreover, in the presence of REE, the degradation rate of petroleum diesel increasedto twice that of petroleum diesel alone. The pattern of biodegradation in the blends and reasons whybiodiesel is more readily degradable than petroleum diesel are discussed. The biodegradationmonitoring results from both CO{sub}2 evolution and GC methods are compared.
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