Evaluation of the methanogenic potential of anaerobic digestion of agro-industrial wastes

Waste management technologies have become a way to generate value-added products. Anaerobic digestion (AD) allows biogas generation by treating organic wastes. In this work, the methanogenic potentials of anaerobic digestion of rumen and chicken manure, two typical agro-industrial wastes from the Colombian Caribbean region, were evaluated. On a first stage, the effect of temperature on anaerobic digestion of manure inoculated with liquid rumen was measured. Results revealed that the thermophilic digestion produces more biogas (up to 47% higher than the mesophilic digestion), but the mesophilic digestion has better biogas quality (up to 20% more methane than the thermophilic digestion). On the second experimental stage, it was assessed the effect of temperature regimen and the addition of fat-oil-grease (FOG) on cumulative biogas production, methane percentage, and physicochemical parameters. It was found that the anaerobic digestion of the rumen with FOG in mesophilic conditions had the best performance in terms of quantity and quality of biogas (2520 NL CH4/kg VS, CH4 93%, H2S 1 mg/L, H2O 16 mg/L). Finally, rumen and manure had methane concentrations above 40% in all cases studied, after 60 days of anaerobic digestion. It was concluded that rumen and manure are good candidates for biogas generation.