In-situ methane enrichment in continuous anaerobic digestion of pig slurry by zero-valent iron nanoparticles addition under mesophilic and thermophilic conditions

The effect of zero-valent iron nanoparticles (nZVI) addition on methane production during anaerobic digestion pig slurry was assessed. Experiments were conducted using two experimental set-ups: batch and long-term continuous operation at a fixed nZVI dosage. Two different temperature ranges (mesophilic thermophilic) Biogas content monitored, the specific methanogenic activity biomass oxidation state evaluated times. results experiments mesophilic showed an inhibition all tested dosages (42, 84, 168 254 mgnZVI g?1 VSS concentrations), while boosted with lowest dosage in thermophilic operation. In operation, produced increase biogas, achieving values between 80 85% both ranges. average rate increased 165% 94% respect to control range, respectively. value +3 almost immediately after contact substrate slower progressive reactors obtained indicate that is interesting strategy for situ biogas upgrading.