Anaerobic co-digestion of chicken manure and perennial ryegrass: Methane yield and kinetic study

Abstract. Anaerobic digestion is a sustainable method for producing methane, particularly when some of the traditional material is substituted with lignocellulosic biomass. Plant biomass breakdown is hindered by the presence of lignin, resulting in reduced efficiency. Perennial ryegrass was used in our study to handle chicken manure, which was utilised as a substrate in anaerobic co-digestion. Various process parameters were evaluated, including the mass ratios of chicken manure to perennial ryegrass: M1 (100% RG), M2 (100% CM), M3 (25% CM: 75% RG), M4 (50% CM: 50% RG), and M5 (75% CM: 25% RG), as well as a process temperature of 35°C and duration of 30 days. The optimal mixing ratio of CM to RG was determined to be 50% CM and 50% RG (M4), which yielded the highest cumulative methane production of 73.566 LCH₄/ KgVS. The modified Logistic model is very appropriate for this investigation compared to the modified Gompertz model, as indicated by the elevated R2 values (0.994-0.999).