Cobalt nanoparticles to enhance anaerobic digestion of cow dung: focusing on kinetic models for biogas yield and effluent utilization

The impacts of Co nanoparticles (NPs) on the anaerobic digestion (AD) of cow dung were investigated using kinetic models (modified Gompertze, logistic, and first-order) and experimental measurements. The deviation between the predicted and measured data for biogas yield with modified Gompertze and logistic models were 0.66–2.26% and 1.43–4.19%, respectively. The addition of Co NPs (1–3 mg/L) improved the hydrolysis rate (K) value by 66.66–144% compared with the control. Furthermore, the fertilizer efficiency of effluent with Co NPs was comparable to that of commercial NPK compound fertilizer. The combination of kinetic models and experimental measurements can effectively quantify the impact of Co NPs on AD performance and provide an informed choice for industrial production.