577 / 2018-11-02 15:38:38

Anaerobic acidogenic fermentation from corncob hydrolysate during the two-phase anaerobic digestion

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Acidogenic fermentation was carried out with corncob hydrolysate as feedstock for volatile fatty acids (VFAs) production. Different inoculum to substrate ratios (ISR) of 0.5:1, 1:1 and 2:1 were investigated. The highest VFA yield was obtained at ISR of 0.5:1.VFAs composition analysis showed that butyric acid was the predominant acid, followed by acetic acid and propionic acid. Anaerobic sludge and aerobic sludge were selected as different seed sources. The results showed that VFAs production increased slightly when anaerobic sludge was used relative to aerobic sludge. The optimum VFA yields were 0.38 g/g COD-added for anaerobic sludge and 0.32 g/g COD-added for aerobic sludge, which were observed after 5 d fermentation, respectively. The microbial community diversity of inoculum and digestate was analyzed. Two types of inoculum had distinct bacterial community structures, but they did share a common set of core communities that included Firmicutes, Chloroflexi, Proteobacteria and Bacteroidetes. The bacterial community compositions of the digestate changed a lot compared with those in inoculum, which mainly consisted of Firmicutes. Therefore, the aerobic sludge could be an option as the acidogenic inoculum.