Enhancing Methane Production through Co-Digestion of Corn Stover, Dairy Manure and Tomato Residues with Rumen Microbiota

Abstract The lignocellulosic agro-residues such as corn stover are indeed abundant but still recalcitrant due to the presence of lignin. In the present study a co-digestion of corn stover, dairy manure, tomato residues enriched with rumen microbiota was implemented to enhance production of biogas. In batch Biological Methane Production (BMP) assays ( n = 3) the corn stover mixture yielded 196.41 mL/g VS added , which corresponds to a 9.3-fold increase compared to corn stover alone. Moreover, corn stover mix in rumen fluid at different ratios of 4%, 6%, and 12% w/v improved the biogas production by 28.6-, 21.6-, and 18.3-fold, respectively. Furthermore, two continuous flow tank reactors (CSTRs) operated under identical conditions, except for the biological treatment approach. Both reactors were fed daily with corn stover mix residue at varying organic loading rates (OLR 1–5 g VS/L.d). According to the findings, inoculation with rumen fluid microorganisms improved methane production by at least 1.3- fold as they accelerate the degradation of cellulose structure. Microbial community analysis via 16S rRNA sequencing revealed that the presence of rumen fluid altered both bacterial and archaeal populations. Notably, rumen-enriched reactors were dominated by the genera Clostridium (14.45 ± 0.15), Saccharofermentans (19.23 ± 0.17), and Methanoculleus associated with enhanced hydrolysis and methanogenesis. These shifts in microbial composition corresponded to improved degradation of lignocellulosic material and higher methane production. The combined strategy of co-digestion and rumen microbiota treatment presents a sustainable and efficient solution for energy recovery from agricultural waste. Graphical Abstract