Anaerobic Digestion of Water Hyacinth (Eichhornia crassipes) using Cow Dung Inoculum for Enhanced Biogas Production

Background and Objective: Anaerobic digestion is an environmentally sustainable biological process that converts organic biomass into biogas through the activity of microorganisms under oxygen-free conditions. This study investigated the influence of cow dung inoculum on the anaerobic digestion of Water Hyacinth (Eichhornia crassipes) leaves for biogas production. Materials and Methods: Fresh leaves of Water Hyacinth (Eichhornia crassipes) were collected within Sokoto metropolis and subjected to anaerobic digestion, with cow dung serving as the inoculum in the inoculated treatment. Anaerobic digestion was carried out using inoculated and uninoculated substrate of Water Hyacinth (Eichhornia crassipes) leaves by water displacement method, while temperature and pH were determined using pH meter and thermometer. Data were subjected using descriptive analyses. Results: The inoculated digester produced a higher cumulative biogas yield (620.50 cm³) compared to the uninoculated digester (240.30 cm^3). The inoculated system recorded a shorter retention time (18 days) and higher average daily gas production (34.47 mL/day) compared to the uninoculated digester (26 days; 9.24 mL/day). The pH of the inoculated digester ranged from 6.69 before digestion to 8.11 after digestion, while the uninoculated system ranged from 5.78 to 6.57. The operating temperature ranged between 30 and 35°C, which is within the mesophilic range suitable for anaerobic digestion. Percentage degradation was higher in the inoculated substrate (72.40%) than in the uninoculated substrate (61.30%). Conclusion: The study concludes that the addition of cow dung inoculum significantly enhances anaerobic digestion efficiency by increasing biogas yield. Future studies should focus on co-digestion with other aquatic weeds to further improve biogas production.