Effect of Organic Loading Rate on Anaerobic Digestion of Food Waste under Mesophilic and Thermophilic Conditions

This study investigated the effect of organic loading rate (OLR) on anaerobic digestion (AD) of food waste under mesophilic and thermophilic conditions. Results showed that the performance of the AD system was distinctly influenced by temperature and OLR in terms of biogas production, intermediate metabolism, and degradation performance. The optimal OLR under thermophilic condition was 2.5 g of volatile solids (VS)/L/day with methane yield (MY) of 541 mL/g of VSadded. In addition, the optimal OLR under mesophilic condition was 1.5 g of VS/L/day with a MY of 371 mL/g of VSadded. At the same OLR, the MY under thermophilic condition was 33–49% higher than that under mesophilic condition. Under thermophilic condition, steady methane production and degradation efficiency were achieved with considerably high OLR of 7.5 g of VS/L/day. Under mesophilic condition, stability was obtained only when the OLR was controlled below 2.5 g of VS/L/day. Results also revealed that food waste is a highly desirable substrate with a high bearing OLR under the thermophilic condition of biogas production.