Fermentative production of hydrogen from wheat bran by mixed anaerobic cultures

In the present studies, treatment of wheat bran was carried out with the intention to produce hydrogen during the anaerobic degradation process. The effects of the hydrogen-producing microbial sources, pretreatment condition, substrate concentration, inoculum concentration, and initial pH on the hydrogen production were investigated in batch cultivations. The activated sludge of paper mill in Sui County exhibited a better hydrogen production ability in contrast with the other three natural microbial sources, and the predominant hydrogen-producing bacteria were identified as Clostridium sp. The conventional acid pretreatment of wheat bran was essential for adequate converting wheat bran into biohydrogen. The contents of soluble saccliarides in the pretreated wheat bran increased from 0.086 g/g total solid (TS) to 0.392 g/g-TS compared with the raw wheat bran. The maximum hydrogen yield of 128.2 mL/g total volatile solid (TVS) and hydrogen production rate of 2.50 mL/(g-TVS h) were obtained at an initial pH 5.0, 80 g/L of pretreated wheat bran, and 60 g/L of activated sludge of paper mill. The maximum hydrogen content in the biogas was 62% (v/v), and there was no significant methane observed. In addition, biodegradation characteristics of the wheat bran by microorganisms were also discussed. Both butyrate and acetate were main byproduct in the metabolism of hydrogen fermentation.