Effect of 5-hydroxymethylfurfural (5-HMF) on high-rate continuous biohydrogen production from galactose

This study investigated the effect of 5-hydroxymethylfurfural (5-HMF) on high-rate continuous fermentative H2 production in a lab-scale fixed bed reactor (FBR) inoculated with mixed culture granules and fed with 15 g/L galactose at a hydraulic retention time of 6 h and at 37 °C. During the 83 days of operation, 5-HMF up to 2.4 g/L was spiked into the feedstock. The maximum hydrogen production performance of 26.6 L/L-d and 2.9 mol H2/mol galactoseadded were achieved at 5-HMF concentration of 0.6 g/L. 5-HMF concentration exceeding 0.9 g/L not only inhibited hydrogen production but also affected the biofilm structure and microbial community population. However, when 5-HMF was eliminated from the feedstock, the performance and microbial community population were rapidly recovered.