Waste-to-energy valorisation of municipal solid waste using elephant grass and abattoir waste as co-substrates

Abstract

This study examined the anaerobic co-digestion of the organic fraction of municipal solid waste (OFMSW), elephant grass (EG), and abattoir waste (AW) to boost biomethane production in Kumasi, Ghana. Analyses of physicochemical, ultimate, lignocellulosic, and organic fractions showed that the substrates have complementary traits suitable for anaerobic digestion. Elephant grass had high carbohydrate levels and low lignin, while abattoir waste supplied nitrogen-rich compounds to enhance nutrient balance during digestion. Biomethane potential (BMP) tests under mesophilic conditions with various substrate mixes revealed that EG100 generated a total methane yield of 275.55 mL CH₄ g⁻1 VS, a 26.7% increase over OFMSW mono-digestion (217.51 mL CH₄ g⁻1 VS). AW100 produced 155.52 mL CH₄ g⁻1 VS. The co-digested mixture O50EG50 achieved the highest methane yield of 346.70 mL CH₄ g⁻1 VS, representing a 59.4% increase over mono-digestion of OFMSW. The modified Gompertz model estimated an ultimate methane yield (G₀) of 531.37 mL CH₄ g⁻1 VS for O50EG50, about 142.3% higher than for OFMSW alone, indicating that the co-digestion conditions need optimisation. These findings indicate that co-digesting OFMSW with elephant grass significantly enhances biomethane output and offers a sustainable waste-to-energy strategy for Ghana.