Effect of severity on dilute acid pretreatment of lignocellulosic biomass and the following hydrogen fermentation

This study aimed to investigate the relationship of the severity of dilute acid pretreatment and the following dark hydrogen fermentation performance. Empty palm fruit bunch, rice husk, and pine tree wood were hydrolyzed in 5% (v/v) H₂SO₄ at 10% (w/v) solid/liquid ratio and 121 °C for 30, 60, and 90 min, and then used as the substrate of batch hydrogen fermentation. The maximum sugar yield was achieved at pretreatment with 60 min reaction time; however, it did not guarantee the maximum H₂ production. Hydrolyzate obtained from pretreatment where the combined severity factor was at or over 2.01 showed severe 5-hydroxymethylfurfural production and consequent decrease of H₂ production rate. Peak H₂ production rates of 2640, 3340, and 2565 mL H₂ L⁻¹ day⁻¹ were achieved at the following severity factors: 1.95, 1.86, and 1.83, for empty palm fruit bunch, rice husk, and pine tree wood, respectively.