Assessment of bioethanol fermentation performance using different recycled waters of an integrated system based on food waste

To utilize the process water during ethanol fermentation from food waste saccharification broth, the water obtained after three types of technology—methane fermentation, electrodialysis, and microbial fuel cell—were utilized in recycle fermentation in food waste ethanol fermentation. The food waste methane water (FWS), electrodialysis water (FEW), and microbial fuel cell water (FWM), were compared with tap water in terms of ethanol fermentation, volatile fatty acid production, and other parameters. The results indicated that fermentation time was reduced by 50% using both FEW and FWM recycling. Among the different recycled water, FEW recycling in ethanol fermentation motivated yeast growth, yielding the highest ethanol value of 47 g/L. The pH changes in the fermentation systems during 60 h using the different recycled waters were within the optimal range of ethanol fermentation (pH 4.0 to 5.0). Moreover, the highest content of acids found in the fermentation systems were 15 g/L and 11 g/L for lactic and formic acid, respectively, which was less than the inhibition values reported. There was no significant inhibition of ethanol fermentation system due to the presence of VFAs. This study will aid the development of an integrated treatment plant for food waste and biofuel production.