Anaerobic co-digestion of food waste with pretreated yard waste: A comparative study of methane production, kinetic modeling and energy balance

Solid state anaerobic digestion of food waste (FW) with yard waste (YW) appears to be an efficient technique for bioenergy production. However, the reluctant nature of YW and nutrient imbalance due to high C/N ratio are the two major obstacles for maximum methane production. In this study to improve the methane production potential, YW was thermally pretreated to reduce its recalcitrance nature and then the pretreated YW was co-digested with FW to balance nutrient for anaerobic co-digestion. Moreover, optimization of F/M (Food/Microorganism) ratios (1.0, 1.5, 2.0 and 2.5) for solid state anaerobic co-digestionwas also considered. The highest methane production of 431 mL/gVS(added) was observed for co-digestion of FW with microwave pretreated YW at the F/M ratio of 1.5. Energy balance of the pretreatment technique was conducted and the highest net energy gain 3.98 kJ/gVS (= output energy of 14.04 kJ/gVS - input energy of 10.05 kJ/g VS) obtained at the F/M ratio of 1.0. (C) 2019 Elsevier Ltd. All rights reserved.