GLRPPR Sector Resource: Whole-cell Biocatalysts for Producing Biodiesel from Waste Greases
Whole-cell Biocatalysts for Producing Biodiesel from Waste Greases
This research examined the use of whole-cell biocatalysts to produce biodiesel at room temperature (25oC). Rhizopus oryzae (ATCC 10260) was used to catalyze the conversion of virgin and waste oils (triglycerides) into biodiesel fuel (fatty acid methyl ester, FAME) in the presence of 15% water. Results indicate that the whole-cell biocatalyst can produce about a 90% yield of FAME from virgin oil, and nearly complete conversion of the remaining oil into free fatty acid (FFA), using a 96-hour reaction at room temperature (25oC). In a 72-hour reaction, FAME yields were about 75% for virgin oil, 80% for waste vegetable oil, and 55% for brown (trap) grease. Increasing reaction temperature to 35oC dramatically reduced FAME yield. Separating the hydrolysis and methanolysis reactions did not increase yields, nor did the substitution of ethanol for methanol in the reaction. However, there is some evidence that ethanol may either
esterify FFA more quickly than methanol, or result in a more stable ester. Whole-cell biocatalysts may be an effective way to transesterify waste oils or greases that are high in FFAs and difficult to dewater. Brown (trap) grease and similar degraded or complex greases are good candidates for further whole-cell biocatalyst research. Additional research is also needed on reactor design and type of micro-organism that will increase yield and decrease reaction time. Culturing the whole-cell biocatalyst on industrial or residential waste should be explored as a means to reduce costs.
Illinois Sustainable Technology Center
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