Effects of Substrate Concentration and Hydraulic Retention Time on the Production Stability of Volatile Fatty Acids Production from Food Waste

Bioconversion of organics in food waste (FW) to volatile fatty acids (VFAs) via anaerobic fermentation is attractive for sustainable development. In practice, the daily output and composition of FW fluctuate greatly, interfering with the fermentation process. Hydraulic retention time (HRT) and substrate concentration (SC) are easily tunable engineering parameters, but the co-action of HRT with SC is less studied. This study explored the effects of SC (12, 30 and 60 g SCOD/L) on the fermentation performance with different HRT (5.3, 8 and 10.6 days). At 12 and 60 g SCOD/L SC, VFAs yield (85% and 20%, respectively) were depended on SC instead of HRT. Nevertheless, when SC was 30 g SCOD /L, VFAs yield increased as HRT increased. While VFAs production (around 10 g/L COD VFAs ) and composition (butyric acid dominant) were similar under low SC, the microbial community shift greatly