Biocatalysis conversion of methanol to methane in an upflow anaerobic sludge blanket (UASB) reactor: Long-term performance and inherent deficiencies

• Long-term performance of UASB reactor treating methanolic wastewater was evaluated.
• Methanol conversion pathways during UASB process were elucidated.
• UASB process showed inherent deficiencies (granules disintegration) after long-term operation.
• Possible contributors causing disintegration and rupture of granules were proposed.

Long-term performance of methanol biocatalysis conversion in a lab-scale UASB reactor was evaluated. Properties of granules were traced to examine the impact of methanol on granulation. Methanolic wastewater could be stably treated during initial 240 d with the highest biogas production rate of 18.6 ± 5.7 L/L d at OLR 48 g-COD/L d. However, the reactor subsequently showed severe granule disintegration, inducing granule washout and process upsets. Some steps (e.g. increasing influent Ca2+ concentration, etc.) were taken to prevent rising dispersion, but no clear improvement was observed. Further characterizations in granules revealed that several biotic/abiotic factors all caused the dispersion: (1) depletion of extracellular polymeric substances (EPS) and imbalance of protein/polysaccharide ratio in EPS; (2) restricted formation of hard core and weak Ca-EPS bridge effect due to insufficient calcium supply; and (3) simplification of species with the methanol acclimation. More efforts are required to solve the technical deficiencies observed in methanolic wastewater treatment.

Figure optionsDownload as PowerPoint slide