Comparison of harvesting methods for microalgae Chlorella sp. and its potential use as a biodiesel feedstock

Three methods for harvesting Chlorella sp. biomass were analysed in this paper - centrifugation, membrane microfiltration and coagulation: there was no significant difference between the total amount of biomass obtained by centrifugation and membrane microfiltration, i.e. 0.1174 +/- 0.0308 and 0.1145 +/- 0.0268g, respectively. Almost the same total lipid content was obtained using both methods, i.e. 27.96 +/- 0.77 and 26.43 +/- 0.67% for centrifugation and microfiltration, respectively. However, harvesting by coagulation resulted in the lowest biomass and lipid content. Similar fatty acid profiles were obtained for all of the harvesting methods, indicating that the main components were palmitic acid (C16:0), oleic acid (C18:1) and linoleic acid (C18:2). However, the amounts of the individual fatty acids were higher for microfiltration than for centrifugation and coagulation; coagulation performed the most poorly in this regard by producing the smallest amount of fatty acids (41.61 +/- 6.49mg/gdw). The harvesting method should also be selected based on the cost benefit and energy requirements. The membrane filtration method offers the advantages of currently decreasing capital costs, a high efficiency and low maintenance and energy requirements and is thus the most efficient method for microalgae harvesting.