Investigation of the effect of pretreatment methods on lipid yield and fatty acid profile of locally isolated microalgae species

Abstract

The introduction of a novel chemical cell disruption method with economic and environmental feasibility to increase the lipid extraction yield is of paramount importance to enhance the commercialization drive of microalgae biofuels. Recently, researchers have suggested a novel chemical cell disruption method, electro-Fenton’s process (EFP), for microalgal biodiesel production. The present study demonstrates the feasibility of employing EFP incorporating a sacrificial steel anode as a novel approach for microalgal cell disruption. Primarily in the current research, Chlorella sp. has been selected after screening four locally available microalgal species and it was identified as Chlorella homosphaera using molecular identification. Moreover, the effect of chlorophyll removal on the FAME profile and quality of biodiesel produced using C. homosphaera were evaluated where chlorophyll removal significantly improved the biodiesel quality while reducing the resulted lipid yield. Selected process parameters of the electrolytic cell were optimized using the electro-generation of H2O2 prior to the EFP experiments. Subsequently, the electrolytic cell with the optimized reactor parameters was employed in microalgal cell disruption via EFP incorporating a sacrificial steel anode where two process parameters, namely reaction time and the biomass concentration, were optimized. Moreover, results were compared with wet (WT) and dry (DR) lipid extraction methods without cell disruption. The EFP showed a significant improvement in lipid yield over the WT method and comparatively higher biodiesel quality than WT and DR methods. Finally, the results obtained for optimized EFP were analyzed comparatively with four conventional mechanical methods. According to the results, EFP contributed to the production of biodiesel with comparatively improved quality than that of mechanical cell disruption methods. Thus, the results of the present study demonstrate that the EFP could be a promising method for industrial-scale applications owing to the ability to produce high-quality biodiesel compared to conventional mechanical methods. Keywords: microalgae, lipid yield, chlorophyll removal, electro-Fenton’s process, chemical cell disruption