Potential of volatile fatty acids production from banana waste juice: Impacts of storage, substrate phase, operation conditions, and microbial community analysis

In this study, banana waste juice (BWJ) was chosen as the fermentation substrate to produce VFAs by anaerobic fermentation. The storage and substrates phase together with operation conditions including inoculum amount, initial pH and temperature on producing VFAs were explored. With the extension of storage time for raw banana waste (BW), pH value and TS of BWJ decreased, while soluble sugar and SCOD increased first and then decreased. Proper storage of raw BW and separation of juice-residue can promote the yield of VFAs more than 3 times. When the storage time of BW was 4 days and inoculum amount was 3 gTS/L, VFAs yield of BWJ reached the maximum (227.34 mgCOD/gVS) at initial pH 9 and 35 C-degrees, which was 1.74 and 2.53 times that of banana waste mixture (BWM) and banana waste residue (BWR), respectively. Moreover, BWJ was more suitable for VFAs production due to its least fermentation time to reach the maximum yield (day 4), which was 1 and 4 days shorter than that of BWM and BWR. During the fermentation, Bacteroidetes and Firmicutes became dominated, which were positively correlated with VFAs. This study provided valuable information for the disposal of organic waste and production of VFAs, which can realize efficient and feasible resource utilization in practical application.