Sequencing batch reactor enhances bacterial hydrolysis of starch promoting continuous bio-hydrogen production from starch feedstock

Bio-hydrogen production from starch was carried out using a two-stage process combining thermophillic starch hydrolysis and dark H-2 fermentation. In the first stage, starch was hydrolyzed by Caldimonas taiwanensis On1 using sequencing batch reactor (SBR). In the second stage, Clostridium butyricum CGS2 was used to produce H-2 from hydrolyzed starch via continuous dark hydrogen fermentation. Starch hydrolysis with C. taiwanensis On1 was operated in SBR under pH 7.0 and 55 degrees C. With a 90% discharge volume, the reducing sugar (RS) production from SBR reactor reached 13.94 g RS/L, while the reducing sugar production rate and starch hydrolysis rate was 0.92 g RS/h/L and 1.86 g starch/h/L, respectively, which are higher than using other discharge volumes. For continuous H-2 production with the starch hydrolysate, the highest H-2 production rate and yield was 0.52 L/h/L and 13.2 mmol H-2/g total sugar, respectively, under a hydraulic retention time (HRT) of 12 h. The best feeding nitrogen source (NH4HCO3) concentration was 2.62 g/L, attaining a good H-2 production efficiency along with a low residual ammonia concentration (0.14 g/L), which would be favorable to follow-up photo H2 fermentation while using dark fermentation effluents as the substrate. (c) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.