Influence of Water Content and Upstream Processing on the Liquefied Dimethyl Ether Batch Extraction of Phaeodactylum tricornutum

Extraction of wet algae by dimethyl ether (DME) is promising in view of industrial application as drying can be avoided. In the present work, the marine microalga Phaeodactylum tricornutum was selected due to its favorable lipid content and fatty acid profile. A batch DME extraction was applied and optimized concerning solvent-sample ratio and extraction time. Changes in crude oil extraction yields and fatty acid removal with water content were examined by creating slurries with 10-80% water. Additionally, experiments with fresh algae slurry were conducted. Overall, it could be demonstrated that crude oil yields and fatty acid recoveries were enhanced by increasing the feedstock water content to a specific level. Yields of the major fatty acids were increased by 20-110% in comparison to dry DME or reference extractions, and especially, the valuable eicosapentaenoic acid was positively affected by higher water contents. Trials with fresh algae showed that energy-expensive drying and milling were not required as the best results were obtained with untreated and defrosted slurries.

Automated summary

This study optimized the batch extraction of wet algae using dimethyl ether (DME) to avoid drying. The results showed that increasing the water content of the algae samples enhanced crude oil yields and fatty acid recoveries.