Influence of total solid and inoculum contents on performance of anaerobic reactors treating food waste

The aim of this paper was to analyze the biomethanization process of food waste (FW) from a university campus restaurant in six reactors with three different total solid percentages (20%, 25% and 30% TS) and two different inoculum percentages (20–30% of mesophilic sludge). The experimental procedure was programmed to select the initial performance parameters (total solid and inoculum contents) in a lab-reactor with V: 1100 mL and, later, to validate the optimal parameters in a lab-scale batch reactor with V: 5000 mL. The best performance for food waste biodegradation and methane generation was the reactor with 20% of total solid and 30% of inoculum: give rise to an acclimation stage with acidogenic/acetogenic activity between 20 and 60 days and methane yield of 0.49 L CH4/g VS. Also, lab-scale batch reactor (V: 5000 mL) exhibit the classical waste decomposition pattern and the process was completed with high values of methane yield (0.22 L CH4/g VS). Finally, a protocol was proposed to enhance the start-up phase for dry thermophilic anaerobic digestion of food waste.