Biogas production through anaerobic co-digestion of rice husk and plantain peels: investigation of substrate mixing ratios, digestate quality, and kinetic analysis

Abstract

The increasing accumulation of agricultural residues like rice husk (RH) and plantain peels (PP) poses environmental challenges, necessitating efficient waste management strategies. The study explores the potential of anaerobic co-digestion (AcoD) as a sustainable solution, specifically investigating its capacity for biogas generation from these agricultural residues. The primary objective is to determine the optimal substrate mixing ratios (SMRs) to maximize biogas yield. In-depth examination revealed that the highest biogas production reached a significant 2880 mL with a blend of 60% RH and 40% PP (RH60PP40). Additionally, the 80% RH and 20% PP composite (RH80PP20) demonstrated a substantial yield of 1996 mL. However, when plantain peels were used as the major substrate, biogas outputs decreased to 1250 mL and 173 mL for RH40PP60 and RH20PP80, respectively. Synergistic indexes (SI), measuring compatibility, reported values of 1.36 and 1.96 for the most promising samples, underscoring their optimal blending for biogas enhancement. From the perspective of digestate quality, plantain peel-based digestate (PP100D) stood out as a leading biofertilizer candidate due to its enriched nutrient profile. For the kinetic analysis, the logistic model was identified as the most predictive, outperforming the exponential and modified Gompertz models in mapping biogas production dynamics. Conclusively, the study accentuates that strategically optimized anaerobic co-digestion (AcoD) of RH and PP not only amplifies biogas outputs but also presents a viable, sustainable avenue for managing the environmental concerns associated with unchecked agricultural residue accumulation.