Influence of pressures up to 50 bar on two-stage anaerobic digestion

• DOI: 10.1016/j.biortech.2017.02.013
• Publication Date: 2017-02-08T04:17:36Z
• Authors: Wolfgang Merkle; Katharina Baer; Jonas Lindner; Simon Zielonka; Felix Ortloff; Frank Graf; Thomas Kolb; Thomas Jungbluth; Andreas Lemmer
• Keywords: Biological Oxygen Demand Analysis; info:eu-repo/classification/ddc/660; 660; ddc:660; Carbon Dioxide; Hydrogen-Ion Concentration; 01 natural sciences; 7. Clean energy; 6. Clean water; Chemical engineering; Bioreactors; 13. Climate action; Biofuels; Pressure; Anaerobiosis; Methane; Biotechnology; 0105 earth and related environmental sciences

The concept of pressurized two-stage anaerobic digestion integrates biogas production, purification and pressure boosting within one process. The produced methane-rich biogas can be fed into gas grids with considerably less purification effort. To investigate biogas production under high pressures up to 50bar, a lab scale two-stage anaerobic digestion system was constructed including one continuously operated pressurized methane reactor. This investigation examined the effects of different operating pressures in methane reactor (10, 25, 50bar) on biogas quantity and quality, pH value and process stability. By increasing operating pressures in methane reactor, the pH value decreased from 6.65 at 10bar to 6.55 at 50bar. Simultaneously, methane content increased from 79.08% at 10bar to 90.45% at 50bar. The results show that methane reactors can be operated up to 50bar pressure continuously representing a viable alternative to commonly used gas upgrading methods because of reduced purification effort.