Harvesting of Chlorella Vulgaris Biomass by Using Different Bio-Flocculants: A Comparison Study

Abstract

In the present study, several natural flocculants were extracted from natural resources to harvest Chlorella vulgaris. Jar tests were carried out to evaluate the flocculation efficiencies of the extracted flocculants in harvesting C. vulgaris cells. Chitosan and maize seeds were proven to be effective flocculants as they achieved more than 80 % efficiency after one (1) hour and four (4) hours of sedimentation time, respectively. Under the optimum flocculation conditions of pH 7, 2 mg/L dosage, 120 rpm of stirring speed for chitosan; and pH 3, 450 mg/L of dosage, 15 rpm of stirring speed for maize seeds flocculant; the flocculation efficiencies up to 97.9 % and 84.7 % are able to achieved, respectively. A scale-up study was done to test the flocculation ability of chitosan and maize seeds extracts to harvest 1 L of C.  vulgaris. Approximately 97 % and 82 % of flocculation efficiencies were achieved by chitosan and maize seeds flocculants, respectively, under their optimum flocculation conditions. Comparatively, chitosan offer superiority in flocculating C. vulgaris than maize seeds ex tract in terms of floc size, dosage and sedimentation time.