Using a statistical approach to model hydrogen production from a steam exploded corn stalk hydrolysate fed to mixed anaerobic cultures in an ASBR

摘要

In this study, hydrogen (H_2) production from the fermentation of steam exploded corn stalk (CS) liquor was statistically optimized using a fractional factorial design approach. The factors under consideration included temperature, pH and hydraulic retention time (HRT). Under optimal conditions at 53 ℃, a pH at 4.5 and a 9.5 h HRT, the observed maximum H_2 yield of 98 ± 2 mL g~(-1) TVS together with negligible CH_4 were similar to the model predicted responses. A flux analysis revealed negligible homoacetogenic activity in cultures at 53 ℃ and low pH (≤5.5). Both homoacetogenic (R17) and methanogenic (R28 and R29) fluxes accounted for more than 68-90% of H_2 consumption in cultures at low temperatures. The low H_2 yields observed in cultures maintained at 21 ℃ and 37 ℃ was associated with high lactate and solvent levels. High H_2 yields in cultures at 53 ℃ were associated with a higher abundance of Clostrdium sp. and CH_4 production at low temperatures was due to the presence of hydrogenotrophic methanogens (Methanothermobacter marburgensis and Meth-anobrevibacter ruminatum) and aceticlastic methanogens (Methanosaeta sp. and Meth-anosarcina sp.). The results obtained from this study (within the factor ranges investigated) indicated that steam exploded CS liquor could be a potential substrate for H_2 production using mixed microbial cultures.