Supplementing granular activated carbon for enhanced methane production in anaerobic co-digestion of post-consumer substrates

Granular activated carbon (GAC) as an economic and robust amorphous material could facilitate the syntrophic metabolism of acetogenesis and methanogenesis during anaerobic digestion of post-consumer substrates. In this study, influences of supplementing GAC on anaerobic co-digestion of brewery waste activated sludge and food waste for the production of methane were investigated by analysing the VFA production, ammonia concentration, pH, oxidation reduction potential, and electrical conductivity. Our data showed that a 45% increase in methane production with adding 1.5% (g/g) GAC was achieved. The maximum amount of 478 mL CH₄/g volatile solids (VS)_added was recorded along with 64% VS removal efficiency under a high ammonia concentration of 1420 mg L⁻¹. Moreover, the analysis of scanning electron microscopy exhibited the formation of biofilms with the supplement of GAC. Our results elucidate that GAC evidently enriched activities of hydrolysis and acetogenesis and enhanced the electron transfer efficiency for methanogenesis, which improved the production of methane significantly. Our results also demonstrate that the supplementation of GAC is an efficient method for the enhancement of biogas production from post-consumer wastes.