Factors affecting the fatty acid profile of wastewater-grown-algae oil as feedstock for biodiesel

Abstract

This study analyzes the influence that the environmental conditions and media composition have on the quality of wastewater-grown-microalgae lipids as a feedstock for biodiesel. A two-level full factorial design with three factors (organic carbon content, CO2 supply, and light intensity), followed by a PCA were utilized to explore relations among the variables. The content of SFAs, MUFAs, and PUFAs in the algal lipids ranged between 30.9 and 56.6%, 16.4–62.1%, and 4.7–27.9%, respectively. Light intensity was the major factor affecting lipids composition, followed by CO2. Experimental conditions at the lowest light intensity and the highest CO2 content tested in the study (40 μmol·m−2·d-1 and 10% CO2) were related to enhanced productions of MUFAs and increased C16 and C18 contents, which are desirable compounds in the lipids targeted to biodiesel production. Among the components derived from the wastewater mixture used as source of nutrients to microalgae, NH3-N was related to increased MUFAs productions by the cells. Higher contents of organic carbon reduced the unsaturation value, increasing the oxidative stability of the biodiesel. Biodiesel properties of the algal lipids grown under all experimental conditions tested in this study were found to comply with ASTM D6751 and EN 14214 standards.