Characteristics of hydrogen and methane production from cornstalks by an augmented two- or three-stage anaerobic fermentation process.

  • Yuan Lu, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Tsinghua Yuan, Beijing, China
  • Chong Zhang, Department of Chemical Engineering, Tsinghua University, China
  • Hongxin Zhao, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Tsinghua Yuan, Beijing, China
  • Kun Ma, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Tsinghua Yuan, Beijing, China
  • Zuebing Zhao, Institute of Applied Chemistry, Department of Chemical Engineering, Tsinghua University, Tsinghua Yuan, Beijing, China
  • Hongzhang Chen, State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
  • Dehua Liu, Institute of Applied Chemistry, Department of Chemical Engineering, Tsinghua University, Tsinghua Yuan, Beijing, China
  • Xin-Hui Xing, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Tsinghua Yuan, Beijing, China

    • Biomass-based biorefinery technology is a platform for the sustainable industries by shifting to a renewable biomass from the fossil. For more energy recovery and process efficiency, this paper presented an experimental study on the integration of hydrogen and methane production from model cornstalks by a two- or three-stage anaerobic fermentation process augmented with different bacterial strains. The pretreatment for better solubilization of lignocelluloses was carried out physically by steam explosion, with pressure 1.6 MPa for 5 min. The anaerobic activated sludge was taken as the main inoculum. Initial two-stage fermentation and DGGE analysis results showed that accessibility of microbial cells to the biomass was one of the most important rate-limiting factors, and should introduce effective and stable strains into the system, for enhancement of the biogas production and the biomass hydrolysis. We introduced effective Enterobacter aerogens or Clostridium paraputrificum in the hydrogen production stage. 1 kg of cornstalks could produce 21.4 l (0.88 mol) hydrogen by C. paraputrificum M-21 and 35.6 l (1.46 mol) methane in the three-stage process, under mesophilic (37?) cultivation condition. Moreover, in the three-stage process, most soluble sugars (0.482 kg/kg cornstalks) were obtained after the introduction of Clostridium thermocellum in the hydrolysis stage, under thermophilic (55?) and acidic(pH=5.0) cultivation condition. Hydrolysates from 1kg of cornstalks by heat treated sludge and C. thermocellum, could produce 63.7 l (2.61 mol) hydrogen by C. paraputrificum and 114.6 l (4.69 mol) methane, in which we could get 70.9 percent of energy recovery rate based on the combustion values.

    Keywords: Anaerobic fermentation; Biorefinery; Clostridium paraputrificum; Clostridium thermocellum; Cornstalks; Enterobacter aerogens; Hydrogen; Lignocellulosic biomass; Methane