Anaerobic Co-digestion of Chicken Manure and Corn Straw: Gas Production, Biogas Fertilizer Effectiveness, and Microbial Diversity

This study conducted anaerobic co-digestion (AcoD) of chicken manure (CM) and corn straw (CS) with various mixing ratios (1:0, 9:1, 8:2, 7:3, 6:4, 5:5, and 4:6, VS) through batch experiments to investigate gas production performance, changes in biogas slurry fertilizer efficiency, and microbial community. The results indicate that, compared to anaerobic digestion (AD), AcoD promoted methane production and reduced the accumulation of toxic substances, such as ammonia nitrogen. Methane production was the highest when CM and CS were co-digested with a mixing ratio of 7:3 (R-7:3). The degradation rate of organic matter (OM) at R-7:3 was the highest, and both available nitrogen (AN) and available phosphorus (AP) concentrations were at appropriate levels. The concentration of available potassium (AK) increased the most during the digestion process. In addition, the concentrations of heavy metals (Cu, Zn, Cd, Pb, As) in the biogas slurry were below the detection limit. Microbial analysis reveals that Methanosarcina and Sedimentibacter were the primary bacteria responsible for methane production in the system. They are relatively abundant under R-7:3 conditions, which suggests a greater potential for the stability of the AcoD system. Therefore, an appropriate mixing ratio of CM to CS could enhance methane production and system stability, while reducing the risks associated with using biogas slurry in agriculture.