EFFECTS OF HARVESTING METHOD AND GROWTH STAGE ON THE FLOCCULATION OF THE GREEN-ALGA BOTRYOCOCCUS-BRAUNII

Flocculating activity was determined to evaluate the effective harvest ing method and an optimal growth stage for the recovery of the green a lga Botryococcus braunii growing in batch cultures, Flocculating activ ity was highest at 2 weeks of incubation, regardless of harvesting met hods. The degree of flocculation was different with harvesting methods and growth stages. A high pH value (pH 11) was more effective for flo cculation than treatment with aluminium sulphate or a microbial floccu lant, Pestan, until the third week of incubation. The lipid content of the algae on a dry weight basis was unaffected by harvesting methods. These results indicate that the most effective harvesting method is t o adjust pH to 11 after 2 weeks of incubation.