Lutein recovery from Chlorella sp. ESP-6 with coagulants

Highlights: The Chlorella sp. ESP-6 cells were cultivated in photobioreactor at 1.1gl^-1. The cells were disrupted by grinding, ultrasonic and microwave treatments. Chitosan and PACl+chitosan were applied to coagulated algal cells. The presence of coagulants lowers the lutein yield from algal biomass. Affine adsorption of lutein onto chitosan molecules occurred via hydroxyl-amine interaction. Production of algal lutein included cell cultivation, biomass harvesting, cell wall disruption, and subsequent purification if needed. This work cultivated Chlorella sp. ESP-6 cells in photobioreactor to a biomass content of 1.1gl^-1 and then the freezing-grinding, ultrasonic treatment (20 and 42kHz) and microwave treatment were used to disrupt the cell walls for recover intracellular lutein. The grinding recovered more lutein than ultrasound or microwave pretreatment. Single coagulation using >30mgl^-1 chitosan or dual-conditioning using 10mgl^-1 polyaluminum chloride and 10mgl^-1 chitosan effectively enhance sedimentation and membrane filtration efficiency of algal suspensions. However, the presence of coagulants lowers the lutein yield from algal biomass in the subsequent 20kHz ultrasound treatment and purification process. Simulation results revealed affine adsorption of lutein onto chitosan molecules via hydroxyl-amine interaction. The possible drawback by pre-treatment stage should be considered together with the subsequent recovery stage in whole process assessment.