Application of Rapeseed Oil Cake from Biodiesel Production in Methane Co-Digestion with Microalgal Biomass

This study aimed to evaluate the potential benefits of co-digesting rapeseed oil cake, a by-product of biodiesel production, with microalgal biomass. Anaerobic fermentation was carried out under mesophilic conditions using various doses of press residue as a co-substrate. The results demonstrate that the addition of rapeseed oil cake enhances biogas production. The highest biogas yield was achieved during co-digestion with 1 g VS·L^-1 of microalgal biomass and 0.5 g VS·L^-1 of rapeseed oil cake. The average methane content in the biogas was 62.42%. The average hydrogen sulfide concentration ranged from 400 to 700 ppm. The maximum energy yield of 3.76 kWh·kg^-1 DM was obtained from co-digesting microalgal and rapeseed oil cake biomass in a 2:1 ratio.