Anaerobic Codigestion of Slaughter Residues with Agricultural Waste of Amaranth Quinoa and Wheat

Abstract The objective of this research is to experimentally evaluate the anaerobic co-digestion of slaughterhouse residues in the city of Guaranda with straw residues from agriculture, such as: amaranth, quinoa and wheat. The study was carried out on a laboratory scale using 311 ml biodigesters under mesophilic conditions of 37 °C. Anaerobic co-digestion resulted in methane yields of 407 ml CH4/g VS, with a methane content in the biogas of 77% for the mixture of slaughterhouse waste and quinoa (RM-QU (25:75)). The increase in inoculum in the mixtures composed of slaughterhouse residues and quinoa increased the biodegradability between 17 and 22%. However, in the mixtures of slaughterhouse waste and amaranth (RM-AM (0:100)), a further increase in inoculum decreased biodegradability by 5%. To predict and simulate methane production, 5 kinetic models were used: modified Gompertz, logistic equation, transfer, cone and Richards. The cone model was the one that best adjusted the experimental values ​​with those predicted with an R2 of 0.982 to 0.999 and RMSE of 0.61 to 6.92 ml CH4/g VS. The calculation of the theoretical yield was carried out by stoichiometry and elemental analysis of the samples. Theoretical yields ranged between 480-564 ml CH4/g VS for all mixtures of RM with agricultural residues.