Iron oxide nanoparticle-based pretreatment for simultaneous elevated hydrolysis efficiency and methanization augmentation of Chlorella vulgaris biomass

The impact of iron oxide nanoparticle (Fe3O4 NPs) on Chlorella vulgaris biomass solubilization and biogas production was investigated. The maximum hydrolysis efficiency (30 %) was achieved in the presence of 10 ppm of Fe3O4NPs, however, this degree decreased respectively, to 23.4 and 22 % at 15 and 20 ppm. Concurrently, a highest biogas yield (595 mL/g VSin) was attained in reactors fed with pretreated biomass at 10 ppm. A key threshold of 40 min for Fe3O4NPs pretreatment was established to increase organic materials solubilization in reactors. The effort to expand biomass loads over 16 g/L resulted in lower hydrolysis efficiency and a simultaneous drop in the augmentation of biogas production. All pretreated trials steadily displayed higher first-order kinetic constants as compared to control. Therefore, Fe3O4NPs application prior microalgae anaerobic digestion might be a potential strategy to reduce energy input needed for cell wall disruption with the added benefits of biogas production enhancement.