Amati, Allen2026-10-142026-10-142026Amati, A. (2026). Magnetite nano-catalyst enhanced microbial pretreatment of banana pseudostem for improved biogas production. [Unpublished dissertation]. Busitema University.https://bdears.busitema.ac.ug/handle/123456789/10893DissertationThe recalcitrant lignocellulosic structure of banana pseudostem limits its biogas yield, necessitating effective pretreatment. This study optimized nanocatalytic microbial pretreatment using magnetite (Fe₃O₄) nanoparticles and Pleurotus ostreatus to enhance delignification and subsequent biogas production from Ugandan banana pseudostem biomass. Physicochemical characterization revealed moisture content of 89.75%, volatile solids of 75.1% of total solids, a C/N ratio of 41.0, and lignocellulosic composition of 35.5% cellulose, 20.1% hemicellulose, and 13.2% lignin. Magnetite nanoparticles crystallite size 100 nm, showing spherical to octahedral morphology were synthesized via co-precipitation, and P. ostreatus inoculum 3.2 g/L dry mycelium was cultured. Central Composite Design optimization established optimal pretreatment conditions of 3.09% w/w magnetite and 13.14% v/w microbial inoculum, achieving 79.7% delignification with a statistically significant synergistic interaction (p < 0.05). Fourier Transform Infrared spectroscopy confirmed lignin peak reduction at 1510 cm⁻¹ and 1240 cm⁻¹, while X-ray diffraction and scanning electron microscopy validated structural disruption and increased surface porosity. The combined pretreatment produced 0.01997 m3 biogas per 100 g dry biomass which is 47% increase over untreated controls, with methane content of 68.3% and methane yield of 0.00018 m3 CH₄/g VS. Kinetic analysis using the modified Gompertz model revealed shorter lag phase of 2 days and higher maximum production rate 0.00416m3/day, confirming accelerated hydrolysis. The combined pretreatment achieved 59% of the theoretical maximum biogas yield. This green pretreatment technology, integrating nanocatalysis with fungal delignification, offers a sustainable pathway for valorizing banana agricultural residues into renewable energy, with direct applicability to existing fiber decortication operations.enOther