Enhanced hydrogen production from anaerobic fermentation of rice straw pretreated by hydrothermal technology

This study tested the effect of hydrothermal treatment (HTT) at different peak temperatures (150 °C and 210 °C, i.e. HTT150 and HTT210, respectively) and holding time (0–30 min) on the solubilization of rice straw at total solids (TS) of 20% and then subsequent H2 production from resultant substrates. No obvious degradation was detected in lignin content under all tested HTT conditions which did open up the surface structure and have efficient solubilization effect on rice straw. Soluble carbohydrates produced from straw particles during HTT210 was found to have strongly (r = 0.9987) positive correlation with the subsequent H2 yield. The maximum soluble carbohydrates, 80 mg per gram of volatile solids (VS) was achieved under HTT210 and 0 min of holding condition, correspondingly yielding the highest hydrogen production (28 ml/g-VS), about 93-fold higher than the control. Results suggest that holding time is crucial for HTT pretreatment when taking subsequent H2 production into consideration.