Development of an innovative two-stage fermentation process for high-calorific biogas at elevated pressure

The article presents briefly the development of the two-stage HPF beginning with tests in batch reactors, followed by experiments on gas solubility, and proof-of-concept in continuously operated methanogenesis reactors (MR) up to 9 bar. It also represents the effect of incorporating microfiltration (MF) of the feed stream, on improving the biogas quality and process stability of a continuously operated lab scale HPF process. By linking the MF with the HPF, methane volume fraction in the MR increases from 0.86 to 0.94 at 25 bar. Finally, the simulation and experimental results show good agreement with each other thereby making them a good basis for further optimization of the HPF process.