Self-adaptable HAc/NaAc buffer system enhanced biohydrogen production from dark fermentation of cellulose

The pH decrease caused by potential accumulation and dissociation of organic acids is considered a major challenge hindering stable and constant operation in hydrogen production. In this study, a self-adaptable HAc/NaAc buffer system was investigated based on batch dark fermentation hydrogen production (DFHP) metabolic types to control the pH of fermentation process. Results showed that increasing substrate concentration resulted in lower H₂ production yield, especially when the substrate concentration exceeded 10 g/L. A maximum H₂ yield of 2326.25 mL/L was achieved at the HAc/NaAc-buffered group; productions were 2.84 times and 57.7 % higher than the control and NaOH control groups. Our buffer system retarded the decrease of pH, enhanced the selective metabolic flux of acetic acid production, promoted the growth of microorganisms, enhanced microbial secretion of cellulase, and regulated the ratio of NADH/NAD⁺. The research provided a preliminary understanding and reference for the buffer regulatory strategy on organic waste for DFHP.