Characteristics of acidogenic fermentation for volatile fatty acid production from food waste at high concentrations of NaCl

This study explored the effects of NaCl on volatile fatty acid (VFA) production from food waste by acidogenic fermentation. The production and composition of VFAs, and the microbial community in acidogenic fermentation were investigated at four different NaCl concentrations: 10, 30, 50, and 70 g/L, and at 0 g/L (control). The highest VFA production was 0.542 g/g dry weight of food waste at 10 g/L NaCl, and about 23% lower but still high at 70 g/L NaCl. Interestingly, as NaCl concentration increased, the residence time of lactic acid in the reactor increased, and the maximum production also increased. The type of acidogenic fermentation also changed from butyric acid to propionic acid as the NaCl concentration increased. Microbial community analysis showed that a large number of propionibacteria were present at the end of fermentation, indicating their high tolerance to NaCl.