Abstract: Aiming at the shortcomings of low biogas production and low resource utilization of biogas residue in anaerobic digestion treatment of farm waste, this paper prepared biochar (BC) supported zero-valent iron (ZVI) composite material by modifying biogas residue with ferric salt (ZVI-BC) to enhance the anaerobic digestion efficiency of cow manure. The results showed that ZVI-BC has more functional group types, larger specific surface area and porosity. The addition of ZVI-BC has a certain promotion effect on the anaerobic digestion of cow manure. Compared with the control, the gas production and methane volume fraction were increased by 3.35%-26.87% and 7.01%-16.22%, respectively. Low-added ZVI-BC has a more significant promotion effect on methane, which plays an important role in alleviating the accumulation of organic acids, adsorbing the intermediate toxic and harmful products, and increasing the buffering capacity of the system. The research results can provide reference for the study and application of anaerobic treatment of farm waste.
Keywords: iron modified biochar(BC); zero-valent iron(ZVI); cow manure; anaerobic digestion; biogas residue; biogas