pH shaped kinetic characteristics and microbial community of food waste hydrolysis and acidification

Hydrolysis and acidification of food waste under a wide range of pH (4–11) was investigated to maximize volatile fatty acids (VFA) accumulation and H2 production via kinetic model and microbial analysis. To the best of our knowledge, the highest amount of VFA accumulation reached to 53.87 g/L at pH 6 was reported. A kinetic model describing the hydrolysis and acidification process was developed to access the key kinetic parameters. A bipolar effect of pH on hydrolysis rate was first revealed by developed model, monotonical decline on acidification rate with increase of pH was also found. However, the decay rate of both bacteria group showed a bipolar form, resulting in kinetic favorable conditions for VFA accumulation at pH 5. Sequencing of V4-V5 region of 16S rRNA at Illumina Miseq plateform revealed an overwhelming predominance of Lactobacillus and Enterococcus in acidic and alkaline digester, respectively. Correspondence analysis indicated Lactobacillus, Paralactobacillus, and Clostridium contributed to VFA accumulation while Clostridium, Weissella, and Sporananaerobacter played an important role in H2 production.