Energy production from anaerobic co-digestion processing of cow slurry, olive pomace and apple pulp

Abstract

This paper deals with anaerobic co-digestion of cow slurry, apple pulp and olive pomace mixture and results obtained shown that the production of methane by co-digestion of cow slurry, olive pomace and apple pulp is not only possible but also economically and energetically attractive. Tests were performed with a pilot scale anaerobic digester, 128 l in volume, operating under batch and fed-batch condition. The biogas production, methane yield and quality, plus other operating parameters were evaluated under four feeding regimes, to simulate a real situation. Stable biogas production was obtained of about 400 l/kg Volatile Solids at a Hydraulic Retention Time of 40 days in a mixture containing 85% cow slurry, 10% olive pomace and 5% apple pulp (% by volume). The percentage of methane inside the biogas was around 52% and the maximum COD removal was 63%.