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

ThepHdecrease caused by potential accumulation and dissociation of organic acidsis considereda major challenge hindering stable and constant operation in hydrogen production. In this study, a self-adaptableHAc/NaAc buffer system was investigated based on batch dark fermentation hydrogen production (DFHP) metabolic typesto controlthe pH of fermentation process. Resultsshowedthat increasing substrate concentration resulted in lower H₂ production yield, especially when the substrate concentration exceeded 10 g/L. A maximum H₂yield of2326.25 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 buffersystem retardedthe decrease of pH, enhanced the selectivemetabolic flux of acetic acid production, promoted the growth of microorganisms, enhanced microbial secretion of cellulase, andregulatedthe ratio of NADH/NAD⁺. The research provided a preliminary understanding and reference for the buffer regulatory strategy on organic waste for DFHP.