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

Abstract

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. • Sorghum vinegar residue was co-digested with livestock manures at solid state. • Digester stability and methane production were enhanced in anaerobic co-digestion. • Modified Gompertz model corroborated enhanced methanogenesis kinetics in co-digestion. • Vinegar residue addition enriched functional microbes to sustain methane production.