Assessment of the Methane Production Capacity of a 20 m³ Biodigester Fed with Poultry Manure in Côte d’Ivoire

Abstract

This study evaluated the methane-production capacity of a 20 m³ biodigester fed exclusively with poultry manure under field conditions in Côte d’Ivoire. The assessment was conducted at Fondation Brin, Yaokokoroko, Tabagne Sub-prefecture, Gontougo Region, over a 30-day analytical monitoring period. The poultry manure was characterised for moisture content, dry matter, volatile solids, pH, total organic carbon, inorganic carbon, total nitrogen and carbon-to-nitrogen ratio. Digester pH and temperature were monitored, and daily biogas production, cumulative production, methane content and methane yield were evaluated. The substrate contained 65.19 ± 0.81% moisture, 34.81 ± 0.73% dry matter and 72.98 ± 0.91% volatile solids on a dry-matter basis. The initial pH was 8.45, while the carbon-to-nitrogen ratio was 9.01, indicating a nitrogen-rich substrate. During operation, digester pH ranged from 6.00 to 8.35 and temperature from 27.53 to 35.95 °C. Daily biogas production ranged from 5.00 to 7.00 m³/day, with cumulative production of 173.5 m³ over the monitoring period. The mean methane content was 62%, and the mean methane yield was 141.1 L CH₄/kg VS. These results indicate that poultry manure can support continuous methane-rich biogas production in an intermediate-scale biodigester under tropical field conditions, although the low carbon-to-nitrogen ratio remains an important operational constraint.