Wednesday, May 2, 2007 - 11:30 AM

Improved process for harvest and concentration of algal lipid for biodiesel production

David E. Brune and Lance E. Beecher. Agricultural and Biolgical Engineering, Clemson University, McAdams Hall, Clemson, SC 29634

A series of experiments were conducted to evaluate the feasibility of developing lower cost techniques of recovering algal-generated lipid for biodiesel production from large-scale marine algal culture. The most promising technique targets aquatic animal harvest of algal biomass with conversion into easy to extract animal lipid. The animal system studied in these experimental trials was high density Artemia (brine shrimp) culture. The brine shrimp oil content was separated from bulk brine shrimp biomass by grinding the wet animal tissue directly using a Kinematica Polytron homogenizer in a suspension of organic solvents at room temperature. The resulting oil/solvent and water/solvent mixture was further separated using a centrifuge at 3400 rpm for 3 minutes. A variety of solvent trials were examined including hexane and hexane/isopropanol mixtures. Lipid recovery using “in-solvent, wet-grind” was compared to 6-hour Soxhlet lipid extraction. The data support the conclusion that 50 - 75% of the brine shrimp oil may extracted with 4 one-minute room temperature sequential grinds of the wet biomass in a mixture of hexane and isopropanol, followed by gravity separation of the oil-water mixture. Advantages offered by this process include: 1) Capacity of Artemia to grow on a wide variety of algal genera eliminating the need for expensive algal species control techniques in mass algal culture operations, 2) Avoidance of the difficult and costly need to directly harvest, concentrate and dry microalgae biomass and, 3) Significant cost reduction resulting from the ease of extraction of Artemia-oil as compared to solvent boiling used in conventional algal-oil extraction.