Experimental Evaluation of Biogas Potential from Animal Manure, Poultry Litter, and Plant Residues

The present study evaluated the biogas generation potential of animal manure, plant leaf waste, poultry bedding, and their co-digested mixture through anaerobic digestion under controlled laboratory conditions. The effect of substrate composition, C: N balance, biogas quality parameters, and generation rate was investigated to identify an effective feedstock combination for improved renewable energy production. The major conclusions obtained from this study are summarized as follows: Ø    The elemental analysis confirmed that substrate composition significantly influenced the C:N ratio and digestion performance. Animal manure (E-1) exhibited a balanced C: N ratio of 20.8:1, whereas plant leaf waste (E-2) showed a higher C: N ratio of 38.5:1 due to its carbon-rich lignocellulosic structure. Poultry bedding (E-3) exhibited a lower C:N ratio of 17.0:1 because of its higher nitrogen content. Ø    The co-digestion mixture (E-4) achieved an optimized C: N ratio of 28.3:1, which falls within the suitable range for anaerobic digestion. The balanced carbon and nitrogen availability enhanced microbial growth, improved organic matter degradation, and supported stable methane production. Ø    Biogas quality analysis revealed that feedstock characteristics directly affected methane enrichment and fuel properties. The methane concentration of individual substrates varied from 54.1% to 61.2%, whereas the co-digested substrate (E-4) produced the highest methane concentration of 62.7%. Ø    The co-digestion approach improved overall biogas quality by reducing undesirable gas components. The E-4 mixture showed the lowest CO₂ concentration (31.7%) and reduced H₂S content (190 ppm) compared with individual poultry bedding digestion, indicating better gas quality and improved suitability for energy applications. Ø    The calorific value of biogas was strongly influenced by methane concentration. The highest calorific value was obtained for E-4 (23.6 MJ/m³), demonstrating enhanced energy recovery potential compared with individual feedstocks. Ø    The biogas generation rate results confirmed the advantage of substrate mixing. Plant leaf waste (E-2) showed the lowest biogas generation rate (0.50 m³/kg) due to its resistant lignocellulosic structure, while the co-digested mixture (E-4) achieved the highest generation rate of approximately 1.00 m³/kg. Ø    Overall, the results demonstrate that anaerobic co-digestion of animal manure, plant leaf waste, and poultry bedding provides improved digestion stability, enhanced methane production, better biogas quality, and higher energy recovery compared with single-substrate digestion. The optimized feedstock combination represents an effective strategy for agricultural waste management and sustainable renewable energy production. Future studies can investigate the influence of different mixing ratios of animal manure, plant residues, and poultry bedding to further optimize biogas yield and methane enrichment. Long-term continuous digestion experiments using semi-continuous reactors can be conducted to evaluate the practical stability and scalability of the optimized substrate mixture.

[1] Appels, L., Lauwers, J., Degreve, J., Helsen, L., Lievens, B., Willems, K., Impe, J. V., & Dewil, R. (2011). Anaerobic digestion in global bio-energy production: Potential and research challenges. Renewable and Sustainable Energy Reviews, 15, 4295-4301. [2] Kheiredine, B., Kerroum, D., Mossaab, & Bencheikh-Lehocine. (2014). Effect of Starting pH on the Produced Methane from Dairy Wastewater in Thermophilic Phase. Chemical Engineering Transactions, 38, 511-516. [3] Borja, A., Muxica, I., & Franco, J. (2003). The application of a Marine Biotic Index to different impact sources affecting soft bottom benthic communities along European coasts. Marine Pollution Bulletin, 46, 835–845. [4] Budiyono, I. N., Widiasa, S., Johari, & Sunarso. (2010). The Influence of Total Solid Contents on Biogas Yield from Cattle Manure Using Rumen Fluid Inoculum. Energy Research Journal, 1(1), 6-11. [5] Budiyono, I., Syaichurrozi, I., & Sumardiono, S. (2013). Biogas production from bioethanol waste: the effect of pH and urea addition to biogas production rate. Waste Technology, 1(1), 1-5. [6] Vanegas, C., & Bartlett, J. (2013). Anaerobic Digestion of Laminaria digitata: The Effect of Temperature on Biogas Production and Composition. Waste Biomass Valor, 4, 509-515. [7] Ashok Kumar, S., Marimuthu, C., Balaji, E. P., & Shaker, Riswan, S. (2014). Biogas Production from Kitchen Wastewater using USAB Reactor. International Journal of ChemTech Research, 6, 4135-4142. [8] Priadi, C., Wulandari, D., Rahmatika, I., & Moersidik, S. S. (2013). Biogas Production in the Anaerobic Digestion of Paper Sludge. International Conference on Chemical, Biological and Environmental Engineering, 9, 65-69. [9] Bamboriya, M. L., & Akshay Urja. (2012). Biogas Bottling in India. Renewable Energy, 5, 41-43. [10] Zhang, R., El-Mashad, H. M., Hartman, K., Wang, F., Liu, G., Choate, C., & Gamble, P. (2006). Characterization of food waste as feedstock for anaerobic digestion. Bioresource Technology, 98, 929-935.