Isolation of bacteria capable of hydrogen production in dark fermentation and intensification of anaerobic granular sludge activity

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 DW01 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 H₂ production yield represented a 29.5% increase over the unoptimized conditions. Finally, the effect of adding DW01 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 DW01 to a sludge with an age of 335 days compared with the on-intensified sludge. This paper provides a way to alleviate the CaCO₃ deposition by intensifying the activity of H₂[sbnd]and acid-producing bacteria via improving the activity of granular sludge.