Anaerobic Digestion of Cow Dung for Biogas Production in Kara Market, Sokoto, Nigeria

Background and Objective: The increasing demand for renewable energy sources highlights the need for optimizing biogas production. This study investigates the potential of cow dung as a substrate for biogas generation, focusing on the influence of temperature and pH variations on yield. Additionally, key bacterial species involved in the anaerobic digestion process are identified to better understand microbial contributions. Materials and Methods: Anaerobic digestion was conducted using cow dung over 7 weeks/retention periods using the water displacement method, while temperature and pH variations were monitored throughout the study. Bacterial species were isolated and characterized using standard microbiological techniques. Statistical analysis was performed using One-way ANOVA to determine significant differences in biogas production across retention periods, with a significance level set at p<0.05. Results: The highest biogas yield was recorded at 28 days (3223.33±1377.47 mL) at a peak temperature of 36.5±1.5°C, followed by 21 days (2360.00±183.58 mL) at 34.0±1.0°C and 14 days (863.33±100.17 mL) at 31.0±1.0°C. The lowest yield was observed at 42 days (70.00±20.00 mL) at 26.2±1.5°C. The pH analysis revealed a decrease from initial values (7.85±0.211 at 35 days) to lower post-digestion levels, with the lowest pH observed at 28 days (5.59±0.003). The bacterial analysis identified were Bacillus subtilis, Salmonella sp., Escherichia coli, Clostridium sp., Corynebacterium sp., Pseudomonas aeruginosa, and Bacillus cereus. The most predominant species was Bacillus subtilis (29.17%), followed by Bacillus cereus (20.83%) and Escherichia coli (16.67%), while Clostridium sp., had the lowest occurrence (4.16%). Conclusion: The study confirms that biogas yield and temperature trends peak at 28 days, with significant microbial contributions. Future research should explore co-digestion strategies, enhanced temperature regulation, and microbial inoculation to further optimize biogas yield.