Impact of anaerobic co‑digestion of ryegrass (RG) and cow manure (CM) on methane production and kinetic analysis
Tariq Alkhrissat, Sandra Matarneh
Abstract
• The experiments used different ratios of ryegrass (RG) to cow manure (CM), specifically 100 % RG, 100 % CM, 25 % RG: 75 % CM, 50 % RG: 50 % CM, and 75 % RG: 25 % CM (M1, M2, M3, M4, and M5, respectively). • Anaerobic digestion systems designed for a retention duration of 15 to 20 days, during which peak methane production occurred. • The R2 values derived from the adjusted logistic model exceeded 0.993, whilst those obtained from the adjusted Gompertz model were above 0.980. • The highest methane production value recorded for the M4 of 299.048 LCH₄/KgVS. This study investigated the impact of anaerobic co-digestion of ryegrass and cow manure at moderate temperatures (35 °C) for 30 days on methane production. The experiments used different ratios of ryegrass (RG) to cow manure (CM), specifically 100 % RG, 100 % CM, 25 % RG: 75 % CM, 50 % RG: 50 % CM, and 75 % RG: 25 % CM (M1, M2, M3, M4, and M5, respectively). The highest total methane production was achieved at 299.048 LCH₄/KgVS for M4. The hydrolysis percentages in final period for M1, M2, M3, M4 and M5 were 88.57 %, 90.89 %, 93.14 %, 98.82 and 97.43 %. The experimental findings were evaluated using two kinetics models: the modified Gompertz model and the logistics model. The R 2 values derived from the adjusted logistic model exceeded 0.993, whilst those obtained from the adjusted Gompertz model were above 0.980. This research examines the optimized ratio of RG and CM to augment methane generation and compares two kinetic models for performance prediction, offering insights into the enhancement of anaerobic co-digestion systems.