Co-digestion of cattle manure with organic kitchen waste to increase biogas production using rumen fluid as inoculums

Anaerobic co-digestion strategies are needed to enhance biogas production when treating certain residues such as cattle/pig manure. Co-digestion of food waste with animal manure or other feedstocks with low carbon content can improve process stability and methane production. In this study, anaerobic digestion and co-digestion of cattle manure with organic kitchen waste using rumen fluid as inoculums have been experimentally tested to determine the biogas potential. Co-digestion substantially increased the biogas yields by 24 to 47% over the control (organic kitchen waste and dairy manure only). The highest methane yield of 14,653.5 ml/g-VS was obtained with 75% organic kitchen waste (OKW) and 25% cattle manure (CM) additions. In contrast, addition of 75% cattle manure caused inhibition of the anaerobic digestion process, and its cumulative methane yield was 23% lower than that with 25% cattle manure addition.   Key words: Cattle manure, co-digestion, methane, organic kitchen waste, rumen fluid.