This study investigates the potential of using a novel integrated biohydrogen reactor clarifier system (IBRCS) for acetone-butanol-ethanol (ABE) production using a mixed culture at different organic loading rates (OLRs). The results of this study showed that using a setting tank after the fermenter and recycle the settled biomass to the fermenter is a practical option to achieve high biomass concentration in the fermenter and thus sustainable ABE fermentation in continuous mode. The average ABE concentrations of 2.3, 7.0, and 14.6 g ABE/L which were corresponding to ABE production rates of 0.4, 1.4, and 2.8 g ABE/L-reactor h were achieved at OLRs of 21, 64, and 128 g COD/L-reactor d, respectively. The main volatile fatty acids components in the effluent were acetic, propionic, and butyric acids. Acetic acid was the predominant component in the OLR-1, while butyric acid was the predominant acid in OLRs 2 and 3. (C) 2015 Elsevier Ltd. All rights reserved.