Dark fermentative bio-hydrogen production from waste wheat starch using co-culture with periodic feeding: Effects of substrate loading rate

Dark fermentation experiments were performed for bio-hydrogen production from ground wheat starch solution (10 ± 1 g l−1) using periodic feeding and effluent removal. A mixed culture of Clostridium butyricum-NRRL 1024 and Clostridium pasteurianum-NRRL B-598 were used with an initial biomass ratio of 1/1.Effects of wheat starch loading rate on the rate and yield of bio-hydrogen formation were investigated. Substrate loading rate was varied between 0.54 and 5.52 g d−1 (HRT = 6–60 h). The highest hydrogen formation rate (280 ml d−1), volumetric hydrogen formation rate (1857 ml H2 l−1 d−1) and volatile fatty acids (VFAs) concentration were obtained with a substrate loading rate of 5.52 g d−1 (HRT = 6 h). The highest hydrogen yield (109 ml H2 g TS −1) was obtained with a substrate loading rate of 1.38 g d−1.