Optimizing feedstock mixtures of livestock farming wastes to enhance methane yield in biogas production by co-digestion

Abstract

Different mixtures of feedlot manure, rumen content, and corn stover were used to produce biogas with a large percentage of methane by co-digestion. Biogas components from each mixture were identified and quantified using gas chromatography. Cumulative biogas and methane production was measured for 10 mixtures over the course of 15 days. Response surface methodology was implemented to find the optimum mixture. The largest biogas and methane yields occurred in a mixture composed of 75% feedlot manure, 12.5% ruminal content, and 12.5% corn stover, corresponding to a methane yield of 126 ml CH4·g−1 VS with a 7.5% VS content. These findings show that co-digestion of livestock farming wastes is a promising alternative for the production of renewable energy.