Abstract
This study investigated the energy generation potential of pigeon pea waste ,rice straw, and donkey rumen liquor through anaerobic digestion using a 25-liters locally fabricated plastic bio-digester. The digester was constructed and operated at Enugu state university of Science and Technology, Agbani, and was charged with a feedstock-to-water ratio of 1:1:2:2 by mass(6kg each of rice straw and pigeon pea waste, 12kg of donkey rumen liquor and 12kg of water ), achieving a 75% fill level. The retention period spanned 25 days, during which daily biogas production, ambient and slurry temperatures, gas pressure, and pH values were monitored. Biogas production commenced on the 9th day and peaked on the 19th day with a maximum daily yield of 920mL at a slurry temperature of 40°C. The cumulative biogas yield was 9,461mL over the 25-day period, indicating sustained gas production beyond the observation window. The biogas was purified using a multi-stage scrubbing system involving sodium hydroxide, silica gel, activated carbon and water, which resulted in the removal of approximately 92.6% CO₂ and 90% H₂S. Combustion tests confirmed the flammability of the purified gas, suggesting its suitability for domestic applications. Comparative error analysis and statistical tests (MBE, RMSE, MPE and t-test) demonstrated good performance of the constructed digester relative to a 45-liter reference model. The results affirmed the viability of co-digesting agricultural and animal wastes for sustainable energy production, offering a cost-effective solution for waste management and environmental conservation in Nigeria
Keywords
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