Lipid Induction in Scenedesmus abundans GH-D11 by Reusing the Volatile Fatty Acids in the Effluent of Dark Anaerobic Fermentation of Biohydrogen

This study aims to investigate the efficacy of lipid induction in Scenedesmus abundans by adding the effluent from dark fermentation of biohydrogen production. Four sets of experiments were conducted: control (sufficient nitrogen), nitrogen depletion, low concentration (0.3×) effluent addition, and high concentration (0.5×) effluent addition. The addition of low concentration effluent produced the highest biomass and lipid yields of 2.831 g/L and 1.238 g/L, corresponding to a lipid abundance of 43.72 wt%. Furthermore, S. abundans had high removal efficiencies for volatile fatty acids in the effluent (formic acid 100%, acetic acid 100%, propionic acid 98%, lactic acid 84%, and butyric acid 68%), and this is the first study demonstrating the ability of S. abundans in using formic acid and lactic acid to produce biomass and lipids. These results show that S. abundans have great abilities in simultaneous reducing organic acids in the effluent and producing valuable metabolites.