Anaerobic digestates from vinasse promote growth and lipid enrichment in Neochloris oleoabundans cultures

摘要

Neochloris oleoabundans (=Ettlia oleoabundans) is a green microalga that has great potential for the production of biodiesel. To achieve economically viable processes for the production of biodiesel from microalgae, the use of wastewater is highly recommended. However, there are no reports on the cultivation of N. oleoabundans utilizing anaerobic digestates of vinasse or stillage, which is a highly polluting wastewater from the alcohol industry. A first group of experiments was conducted, aiming to establish the optimal culture conditions of N. oleoabundans (UTEX 1185) using anaerobic effluents of vinasse (AEV) in bubble columns incubated under controlled conditions. The highest culture density was obtained in a medium containing 6 % of such effluents with a daily addition of sodium bicarbonate (1 g L−1). The total lipid content varied from 17.7 to 38.5 % for a range of 2 to 8 % of AEV with added sodium bicarbonate. A second group of experiments using 6 % AEV + sodium bicarbonate and flat plate photobioreactor-incubated outdoors was performed. An increase of 62 % in cell density compared to the value registered in Bold’s basal medium (BBM) was observed. Furthermore, a high ammonium–nitrogen removal (85.2 %) and a high flocculation efficiency (42 % after 30 min) indicate that dual-purpose systems aimed at producing high densities of lipid-enriched biomass of this green microalga are feasible. The uses of supplemental bicarbonate and organic waste as a source of nutrients are very important factors that contribute to reducing the cost of production.