Binary and ternary trace elements to enhance anaerobic digestion of cattle manure: Focusing on kinetic models for biogas production and digestate utilization.

The effects of binary and ternary trace elements (TEs) (Fe/Co, Fe/Ni, and Fe/Co/Ni) on the anaerobic digestion (AD) of cattle manure were investigated using kinetic models (first-order, logistic, modified Gompertz, and Coats-Redfern) and experimental measurements. Binary and ternary TEs can significantly improve the biogas production rate and yield potential. The deviation between the predicted and measured data for biogas yield with logistic model (2.1%-5.3%) and modified Gompertz model (0.32%-2.9%) was smaller than that with first-order kinetic model (6.9%-9.9%). The Coats-Redfern model fitting indicated that the activation energy of digestates with trace elements during pyrolysis was reduced by 3.9%-26.2% compared with the control group. Meanwhile, digestates with TEs showed remarkable fertility (5.72%-5.95%). The combination of kinetic models and experimental measurements can effectively quantify the effect of TEs on AD performance and provide an informed choice for industrial production.