Cultivation of Chlamydomonas reinhardtii in Anaerobically Digested Vinasse for Bioethanol Production

This study describes a new algal biofuel process that integrates sugarcane biorefinery wastewater treatment by nutrient removal with algae into bioethanol. The process is free of common industrial problems, including algal contamination, nutrients and fresh water usage, carbohydrate extraction, liquefaction, and saccharification. Cultivation and fermentation were conducted in one step by turning the light-air on and off, respectively. Three series of experiments with Chlamydomonas reinhardtii CC-1093 cultivation and fermentation were performed in anaerobically digested vinasse. Control experiments were a reference to compare the influence of chloride and ammonium-sulfate stress conditions on ethanol yield. Experimental results showed: (1) algal biomass can be successfully cultured within biorefinery wastewater (1129 mg·L −1 ·day −1 ); (2) relatively high bioremediation was achieved (26.1%–83.5%); (3) obtained ethanol yield was (maximum 68.3% of the theoretical yield) in one process step; and (4) the chloride stress condition influences on algae to synthesize extracellular polysaccharides as add-in product (120 mg/L). Graphic Abstract