Enhancement of bioenergy recovery from agricultural wastes through recycling of cellulosic alcoholic fermentation vinasse for anaerobic co-digestion.

• Bioethanol was produced from rice straw (RS) by cellulosic alcoholic fermentation. • Vinasse (VE) was used in anaerobic co-digestion with RS and swine manure (SM). • RS-VE co-digestion enhanced biogas yield and biomethane content. • Highest biomethane productivity (29.2 L kg−1 VS d−1) was recorded with SM-VE. • SM-VE co-digestion showed the highest energy output rate of 2.04 GJ ton−1 dw d−1. Cellulosic alcoholic fermentation generates large amounts of vinasse, which was utilized in the present work to enhance the anaerobic digestion of rice straw and swine manure at different total solid (TS) contents. Straw fermentation resulted in bioethanol and vinasse yields of 95.2 g and 857.7 mL, respectively, per kg dry straw. Vinasse-straw co-digestion showed the highest cumulative biogas yield of 633.4 L kg−1 VS at 3% TS. Therefore, biogas productivity from co-digestion represented 92.1% higher than that of straw mono-digestion. Vinasse-manure co-digestion showed the highest cumulative biogas yield of 676.7 L kg−1 VS at 3% TS at a shorter technical digestion time, which resulted in 53.9% higher biomethane productivity than the corresponding vinasse-straw. Consequently, vinasse co-digestion at all studied TS ratios enhanced the total gross energy output rate (GEOR total) over mono-digestion. Amongst, vinasse-manure co-digestion at 3% TS showed 7.9% higher GEOR total than the highest recorded value from vinasse-straw co-digestion. [ABSTRACT FROM AUTHOR]