O. Salokun

The need for sustainable energy and waste management solutions around the world has made it essential to look into locally available and affordable organic feedstocks for biogas production. This study looks at the possibility of creating biogas through cold (psychrophilic) anaerobic codigestion of two common and often problematic wastes in Nigeria: water hyacinth(WH) and cattle rumen content (CRC), As part of the study, the feedstocks were characterized, daily biogas production and pH variation were calculated, and the efficacy of a 2:1 (CRC:WH) mixture at room temperature without external heating was evaluated. The experiment was carried out with a 5kg batch digester over a 30-day retention time. The feedstock analysis revealed a high moisture content (80.25%) and a chemical oxygen demand (COD) of 69 g/L, indicating a substantial organic load suitable for digestion. After an 11-day lag period, biogas production began, coinciding with a pH increase from 6.13 to 6.73, putting it in the optimal range for methanogenic activity. On the 30th day, a peak biogas yield of 2090 ml was recorded at a pH of 8.46, indicating a direct correlation between increasing pH and increased biogas production. The cumulative production profile clearly demonstrated the sequence of hydrolysis, acidogenesis, and methanogenesis. The study comes to the conclusion that it is both technically possible and efficient to cold co-digest water hyacinth and cattle rumen content in a 2:1 ratio. A balanced microbial environment was produced by the carbonrich water hyacinth and nitrogen-rich rumen content working together to support long-term biogas production.