Abstract—The mesophilic anaerobic co-digestion of Organic Fraction of Municipal Solid Waste (OFMSW) and Waste Activated Sludge (WAS) was conducted to evaluate the effects of alkaline pretreatment using calcium hydroxide (Ca(OH)₂) and catalytic enhancement using ferric chloride (FeCl₃) towards Specific Methane Yield (SMY). Eight setups (A–H) were done to investigate varying combinations of pretreatment and catalytic dosing. Setups A–C served as controls, while setups D–H were pretreated with Ca(OH)₂ at 2.3 g/L for OFMSW and 1.48 g/L for WAS, with FeCl₃ catalyst added at varying dosages ranging from 0 to 0.30 g/L. Among all reactors, setup G (0.20 g/L FeCl₃) exhibited the highest cumulative methane yield (175.31 mL/gVS). Three sigmoidal functions were used to estimate kinetic parameters, with the modified Gompertz function providing the best fit (R² > 0.99) for methane production behavior. Pearson correlation analyses revealed significant relationships (p < 0.05) between FeCl₃ dosing and SMY, indicating that catalytic supplementation beyond 0.20 g/L did not yield additional improvements in methane production. T-test analysis of pH, BOD, and COD confirmed statistically significant differences (p < 0.05) in methane yields between catalyst-enhanced setups and controls. These results suggest that Ca(OH)₂ pretreatment and FeCl₃ catalysis at optimal concentrations significantly enhance methane production from the co-digestion of OFMSW and WAS.
Keywords—anaerobic co-digestion, methane yield enhancement, alkaline pretreatment, ferric chloride catalysis
Cite: Gabrielle Nicole S. Corteza, Kyara Christelle D. Riguerra, and Michelle C. Almendrala, "Enhancing Specific Methane Yield via Mesophilic Anaerobic Digestion: Ferric Chloride Catalysis in the Co-Digestion of Organic Fraction of Municipal Waste (OFMSW) and Waste Activated Sludge (WAS)," International Journal of Environmental Science and Development vol. 17, no. 2, pp. 136-145, 2026.
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