| 초록 |
Several energy-efficient magnetophoretic harvesting methods of oleaginous Chlorella sp. (lipid content, ~41%) cultivated from actual coal-fired flue gas were investigated. Bare magnetic particles (MPs) and their composites coated with cationic functional groups such as chitosan and (3-aminopropyl) triethoxysilane (APTES) were synthesized and evaluated for their performances and recoveries for repeated uses. Algal cells were attached with the MPs by electrostatic interaction and then easily separated from the culture medium by external magnetic field. Chitosan-Fe3O4 composite showed over 99% harvesting efficiency without changing the pH of the culture medium. After harvesting, the reused medium showed no adverse effect on microalgal growth. In the case of APTES-coated BaFe12O19 particles, higher separation efficiencies (~99%) were observed regardless of the size of MPs. However, larger APTES-MPs were more efficient for detachment of APTES-MPs from algae-particle flocs. The bare MPs could be recycled up to 10 times for ~99% and ~97% harvesting and detaching efficiencies, respectively. This magnetic harvesting showed any adverse effect on the algal cell growth or the co-existing bacterial species during repeated cultivations by pH controls below and above isoelectric points. An energy-efficient and environment-friendly process for the extraction of high-value astaxanthin from Haematococcus pluvialis aplanospores (cysts) was developed using the physiological artifice of environmental- and nutritional condition alteration to effect conditions more favorable for dormancy breaking using room-temperature ionic liquid (IL). This process consisted of the natural germination of aplanospores, which allows them to lose their cell-wall rigidity, followed by IL-mediated astaxanthin extraction from the germinating cells. |
