Study of influence of pH and salinity on combined flocculation of Chaetoceros gracilis microalgae

Marine microalgae are a promising feedstock for biodiesel production. In this paper, the influence of pH, salinity and concentration of an inorganic and an organic flocculants on harvesting of marine microalgae Chaetoceros gracilis was studied. Response Surface Methodology was used to analyze the impact of these four variables in combined flocculation process. With the aim to optimize the process, 27 different experiments were carried out and the effect of concentration of ferric chloride (20-50 mg/L), concentration of chitosan (10-50 mg/L), pH (5-9) and salinity (20-40 g/L) were analyzed. Based on obtained results, salinity was the variable with the greatest influence on the harvesting process. In addition, very low doses of the organic polymer (10 mg/L) and the widely used ferric chloride (20 mg/L) were required to achieve 100% microalgal biomass recovery when the salinity was reduced at 20 g/L in the studied range of pH. (C) 2015 Elsevier B.V. All rights reserved.