Pilot-scale biorefining of Scenedesmus obliquus for the production of lipids and proteins

The whole process of algae farming and biomass biorefining was evaluated on a pilot scale for the production of protein concentrate for poultry feeding and crude lipids. Scenedesmus obliquus was produced in open raceway ponds, and the cells were disrupted under low-pressure homogenization operating at 150 bar. Lipids were efficiently extracted using a hybrid multistage process based on a wet extraction using hexane and ethyl acetate, followed by dry extractions using hexane. The protein concentrate containing 43.1% of total proteins was recovered at low centrifugation of 400g and submitted to a desolventization process to remove residual hexane. The protein concentrate showed a similar composition of essential amino acids in comparison to soybean which is the main protein source used in feed formulation. Aspartic acid and glutamic acid were the main amino acids observed in the microalgal protein concentrate. As a feed supplement for broilers, the protein concentrate-based feed showed equal ingestion of the control, but the latter showed lower energy efficiency. The processing of 168 kg of wet biomass (14.8 kg on a dry weight basis) resulted in a production of 1.3 kg of crude lipids and 12.6 kg of protein concentrate, which corresponded to 93.7% of the total dry biomass.