Metal nanoparticle mixtures to improve the biogas yield of cattle manure

Abstract

Metal nanoparticle elements such as Fe, Ni, and Co are promising in improving the performance and stability of anaerobic digestion. However, the impact of nanoparticle mixtures of Fe, Ni, and Co on biogas production from anaerobic digestion of cattle manure still needs further studies. Therefore, this study investigated the effect of the most effective concentrations of nanoparticle additives on biogas and CH4 production and H2S mitigation during anaerobic digestion of cattle manure. The nanoparticle additive concentrations were selected from the findings of previous studies and were 30 mg/L Fe, 2 mg/L Ni, and 1 mg/L Co at four combinations. Biogas production increased by 14.61% upon the use of nanoparticle mixtures of 30 mg/L Fe and 2 mg/L Ni compared with control (cattle manure-only). Furthermore, the addition of nanoparticle mixtures of 30 mg/L Fe, 2 mg/L, and 1 mg/L Co increased CH4 production by 19.30% compared with control. Moreover, H2S production decreased by 35.10% in the presence of nanoparticles mixture of 30 mg/L Fe, 2 mg/L, and 1 mg/L Co in comparison with control. Modified Gompertz and logistic function models were used to determine the kinetic constant of the reaction. The modified Gompertz model has the better predicting ability for cattle manure anaerobic digestion.