Hydrogen and methane production from desugared molasses using a two-stage thermophilic anaerobic process

Authors

  • Prawit Kongjan,

    1. Department of Environmental Engineering, Technical University of Denmark, Lyngby, Denmark
    2. Department of Science, Faculty of Science and Technology, Prince of Songkla University, Muang, Pattani, Thailand
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  • Sompong O-Thong,

    1. Department of Environmental Engineering, Technical University of Denmark, Lyngby, Denmark
    2. Department of Biology, Faculty of Science, Thaksin University, Phathalung, Thailand
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  • Irini Angelidaki

    Corresponding author
    • Department of Environmental Engineering, Technical University of Denmark, Lyngby, Denmark
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Correspondence: Prof. Irini Angelidaki (iria@env.dk), Department of Environmental Engineering, Technical University of Denmark, DK-2800, Lyngby, Denmark.

Abstract

Hydrogen and methane production from desugared molasses by a two-stage thermophilic anaerobic process was investigated in a series of two up-flow anaerobic sludge blanket (UASB) reactors. The first reactor that was dominated with hydrogen-producing bacteria of Thermoanaerobacterium thermosaccharolyticum and Thermoanaerobacterium aciditolerans could generate a high hydrogen production rate of 5600 mL H2/day/L, corresponding to a yield of 132 mL H2/g volatile solid (VS). The effluent from the hydrogen reactor was further converted to methane in the second reactor with the optimal production rate of 3380 mL CH4/day/L, corresponding to a yield of 239 mL CH4/g VS. Aceticlastic Methanosarcina mazei was the dominant methanogen in the methanogenesis stage. This work demonstrates that biohydrogen production can be very efficiently coupled with a subsequent step of methane production using desugared molasses. Furthermore, the mixed gas with a volumetric content of 16.5% H2, 38.7% CO2, and 44.8% CH4, containing approximately 15% energy by hydrogen is viable to be bio-hythane.

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