Techno-economic anaerobic co-digestion feasibility study for two-phase olive oil mill pomace and pig slurry

Abstract

Anaerobic mono- (AmoD) and co-digestion (AcoD) of two-phase olive oil mill pomace (TPOP) and pig slurry (PS) at different ratios were studied in a semi-continuous stirred tank reactor (sCSTR) at mesophilic temperature (37 degrees C). The methane yields for AcoD experiments ranged from 150.9 to 274.3 L CH4 kg VS-1 d(-1). The maximum chemical oxygen demand (COD) removal rate (59.60\%) was achieved for TPOP/PS 80:20 wow substrate composition at OLR 3.68 g VS L-(-1)(reactor) d(-1) and 24 days HRT. Despite the energy production from food waste is not a new process, the industrial implementation and application continue to be a challenge. Hence, the present paper also reports on the economic feasibility study of a full scale anaerobic co-digestion plant to treat 7000 t year(-1) and 1750 t year(-1) of TPOP and PS, respectively. The results of this study are compared against a conventional PS mono-digestion plant. Net present values (NPV) and payback time periods (PBT) were reported to be 782,493 and 135,701 and 6.7 and 9.2 years for AcoD and AmoD plants, respectively. Finally, the sensibility analysis concluded that AcoD configuration is less dependent on energy and compost sale prices variations. (C) 2016 Elsevier Ltd. All rights reserved.