BIODEGRADABILITY OF BIODIESEL IN THE AQUATIC ENVIRONMENT

The biodegradability of various biodiesel fuels was examined by the CO 2 evolution method (EPA 560/6-82-003), BOD5 (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 rapeseed oil and so ybean oil, neat rapeseed oil, neat soybean oil and Phillips 2-D law su lfur; reference petroleum diesel. Blends of biodiesel/petroleum diesel at different volumetric ratios including 80/20, 50/50, and 20/80, wer e also examined. The results demonstrate that all the biodiesel fuels are ''readily biodegradable''. Moreover; in the presence of REE, the d egradation rate of petroleum diesel increased to twice that of petrole um diesel alone. The pattern of biodegradation in the blends and reaso ns why biodiesel is more readily degradable than petroleum diesel are discussed The biodegradation monitoring results from both CO2 evolutio n and GC methods are compared.