RESUMO
Granular activated carbon (GAC) could promote methane production from organic wastes, but a wide range of dosages has been reported. In present study, different GAC dosages of 0, 0.5, 5 and 25â¯g/L were supplemented into anaerobic digesters and the methanogenic degradation kinetics of acetate, propionate and butyrate were characterized, respectively. At high organic load of 5â¯g/L, the degradation rates of propionate and butyrate increased by 1.5-4.7 and 2.5-7.0 times at varied GAC dosages. The methane production rates (Rmax) from propionate and butyrate were significantly elevated when increasing GAC dosage up to 5â¯g/L. However, only a minor increment was found for acetate degradation either at 1â¯g/L or 5â¯g/L. The stimulatory mechanism of GAC for accelerated syntrophic degradation of propionate and butyrate can be primarily attributed to the triggering effect on acetogenesis, as evidenced by the enrichment of syntrophic bacteria e.g. Thermovirga, Synergistaceae, and Syntrophomonas etc.