Mesophilic anaerobic co-digestion of sunflower oilseed processing waste with yeast residues inoculum

• Composition and ISR significantly affect AD efficiency of sunflower oilseed waste. • Sample with 43.7 gVS·/L and ISR 0.276 achieved 81.6% of control SMY. • Thermogravimetric analysis showed less stable components in digested samples. • Managing ISR and SOPW composition is key for optimizing biomethane yield. • Anaerobic digestion enhanced thermal degradation and exothermic reactions. This study investigates the lab-scale mesophilic anaerobic digestion of sunflower oilseed processing waste (SOPW) with yeast residue inoculum (YRI) in batch mode, focusing on the impact of mixture composition and inoculum-to-substrate ratio (ISR) on process efficiency. Sample, containing 43.7 g VS ·L –1 with ISR of 0.276, achieved the highest specific methane yield of 102.9 mL CH4 ·g VS −1 , representing 81.6% of the YRI-control. Thermogravimetric analysis demonstrated that anaerobically digested samples contained less thermally stable components compared to raw substrates. Results highlight the critical role of SOPW composition in optimizing biomethane production and underscore the importance of managing ISR for the effective AD of SOPW.