Enhancing biogas production from livestock manure in solid-state anaerobic digestion by sorghum-vinegar residues

Jiaxing Zhang^a, Chuanren Qi^a, Yaya Wang^b, Yangyang Li^a, Tingting Han^a, Xiaoyan Gong^a

Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation, College of Resources and Environmental Science, China Agricultural University, Beijing, 100193, China.

This study investigated the performance of sorghum vinegar residue to enhance methane production from livestock manures during solid-state anaerobic digestion. Sorghum vinegar residue was co-digested with cattle, sheep, and pig manure, respectively. Results show that co-digesting vinegar residue with livestock manures effectively diluted inhibitory substances (e.g. ammonium, sodium ion, and potassium ion) to alleviate the accumulation of volatile fatty acids and amend microbial composition to enhance digester stability and thus methane production by 10.1 – 58.2%. The highest increase was observed for cattle manure, possibly due to its low inhibitory substances to induce effective synergistic effects with vinegar residue in co-digestion. Modified Gompertz model well fitted the experimental methane yield and exhibited an increase in the maximum methane production rate of livestock manures by 35.2 –58.0% to corroborate their enhanced methanogenesis kinetics with the addition of vinegar residue. Further microbial analyses also indicated that co-digesting vinegar residue with livestock manures enriched hydrolytic bacteria (e.g. the genus vadinBC27_wastewater-sludge_group), acetogenic bacteria (e.g. the genera Syntrophomonas and Petrimonas) and aceticlastic methanogens (e.g. the genera Methanosarcina and Methanosaeta) to promote substrate biodegradation and secure methane production.

Keywords: Livestock manure, Sorghum vinegar residue, Anaerobic co-digestion, Inhibitory substances, Methane production.