In the anaerobic biological treatment of pulp and papermaking wastewater, the gradual deposition of CaCO3 eventually leads to the inhibition of the activity of anaerobic granular sludge. In this study, a hydrogen production bacterial Raoultella DWO1 was isolated from domesticated anaerobic granular sludge. The fermentation conditions were designed using central composite design, and the optimum conditions obtained by response surface analysis encompassed an initial pH 5.77, 4.13 g/L L-glutamic acid and an inoculation amount of 15%. The H-2 production yield represented a 29.5% increase over the unoptimized conditions. Finally, the effect of adding DWO1 on the biogas production in anaerobic granular sludge with different sludge ages was investigated. The cumulative biogas yield and the max biogas production rate increased by 27.8% and 53.5% after adding DWO1 to a sludge with an age of 335 days compared with the onintensified sludge. This paper provides a way to alleviate the CaCO3 deposition by intensifying the activity of H-2- and acid producing bacteria via improving the activity of granular sludge. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.