Enhancing Anaerobic Degradation of Corn Stover Residues and Biogas Production via Rumen Microorganisms

Biotreatment to disrupt the structure of lignocellulosic residues, like corn stover, can be achieved through the hydrolytic ability of rumen microbial communities. This work aims to enhance biogas production from corn stover residues using rumen fluid microbiota. The anaerobic digestibility of corn stover in Biochemical Methane Potential (BMP) tests and continuous stirring tank reactors (CSTR) was examined using rumen fluid as inoculum, in presence of control. Three organic loading rates (OLR), i.e., 1, 2, and 3 g VS/L.d, were tested, to define the optimum OLR for corn stover digestion. Without treatment with rumen microbiota, a low biogas yield, i.e., 25.04 mL/g VS, was obtained during anaerobic digestion of corn stover in BMP tests. Corn stover residues in rumen fluid at 4%, 6% and 12% w/v resulted in cumulative biogas yields of 283, 119 and 88 mL/g VS, respectively. Moreover, experiments to define the optimum corn stover to rumen fluid ratio to optimize biogas production were carried out. Addition of rumen fluid microbiota in the CSTR under various OLRs enhanced biogas production by 2–6.3 times. Corn stover residues in rumen fluid at 4% w/v resulted in the highest biogas production in the CSTR (182 mL/g VS). The addition of rumen inoculum into the anaerobic digester at daily basis was found to be essential to enhance biogas production from corn stover. Testing of the anaerobic biotreatment of corn stover residues with rumen fluid in two-stage anaerobic digestion system appears to be a promising approach.