Biohydrogen and Biomethane (Biogas) Production in the Consecutive Stages of Anaerobic Digestion of Molasses

Anaerobic digestion, whose final products are methane and carbon dioxide, has been used to produce biogas from waste biomass as an alternative energy source. For the purpose of innovative, modern technologies based on microbial processes, it is desirable to separate the hydrogen-(hydrolysis and acidogenesis) and methane-yielding (acetogenesis and methanogenesis) stages of anaerobic digestion to respectively favor the production of hydrogen and methane under controlled conditions. Previously, we developed a benchscale (3- and 3.5-litre bioreactors) two-stage anaerobic digestion system producing hydrogen (in stage 1) and methane (in stage 2) from sucrose-rich by-products of the sugar beet refining industry as the primary energy substrates under mesophilic conditions. Recently, the two-stage system for hydrogen and methane production has been successfully scaled up 10-fold (a pilot scale) and currently operates in one of the Polish sugar factories. The efficiency of hydrogen and methane production were directly proportional to the scale of installation. The obtained results led to the development objectives of further research that the end result will be an innovative solution for the sugar factory as a producer of gaseous biofuels.