Methane Potential and Kinetic Analysis from a Pilot-Scale Anaerobic Digester Fed by Food Waste

Anaerobic digestion of food waste can be performed in a batch-scale or pilot-scale reactor. Batch-scale anaerobic digestion of food waste is performed differently than pilot-scale reactors. Nevertheless, the documentation regarding the performance of a batch pilot-scale anaerobic digestion of food waste is currently lacking. Therefore, this study aims to evaluate the performance of a batch pilot-scale anaerobic digesters fed with food waste (slurry) and the kinetics of methane production. A batch pilot-scale anaerobic digester with 84 L of working volume with an inoculum-to-substrate (I/S) ratio of 2.0 at 70 rpm for 30 min was operated for 26 days. The initial pH of the mixture in the reactor was within the optimum pH, and methane gas production was monitored daily. The Modified Gompertz and Logistic Function models were used for predicting the methane production performance. The digester performed well throughout the study period, and no instability was observed, indicated by the ratio of volatile fatty acid to total alkalinity (VFA/TA) of 0.35. The methane accumulation and ultimate methane yield, respectively, were 463.25 L and 5103.6 mL CH4/g VS. A difference in the ultimate methane yield between the laboratory and the models employed is below 10%, indicating that both models fit well. In conclusion, the batch pilot-scale anaerobic digestion working at ambient temperature efficiently produces methane from food waste (slurry). The Modified Gompertz model obtains a coefficient of determination (r2) of 0.9, which is higher than the r2 obtained in the Logistic Function model, The Modified Gompertz model is deemed to be a more appropriate approach for assessing the methane production produced during the batch pilot-scale anaerobic digestion of food waste (slurry).