Anaerobic biohydrogen production from biodetoxified rice straw hydrolysate

Abstract

Thermal acid hydrolysis is the most common pretreatment method used to deal with waste lignocellulosic biomass. However, furan derivatives (5‑hydroxy-methylfurfural (5-HMF) and furfural) are unavoidably produced and influence downstream biofuel production. Biological methods are superior to physical and chemical methods in detoxifying 5-HMF and furfural because of economic concerns. Integrating the biodetoxification process into the lignocellulose pretreatment and downstream biofuel production procedure is an important issue. The previous novel strain Burkholderia cepacia H-2 capable of quickly degrading 5-HMF and furfural was applied in the biodetoxification process. In this study, the acid sorts and concentration effects on thermal acid rice straw hydrolysis were investigated first. Rice straw hydrolysates with various dilution ratios were then biodetoxified using on-site inoculating novel strain B. cepacia H-2. The biodetoxified rice straw hydrolysate was then used for biohydrogen production using dark fermentation. The highest hydrolysis efficiency and reducing sugar were 49% and 15.6 g/L, respectively when applying 0.5 M HCl to deal with 5% rice straw at 121°C for 15 min. The 5-HMF and furfural in the 2-fold diluted rice straw hydrolysate could be completely biodetoxified within 12 hrs. The hydrolysate hydrogen yields with and without biodetoxification were 0.90 and 0.64 mmol H2/mmol sugar, respectively. The biodetoxification process using the novel strain B. cepacia H-2 was successfully established and could be integrated into the lignocellulose pretreatment and downstream biofuel production procedure as using the rice straw as the feedstock.