Anaerobic co-digestion of chicken manure and banana fiber extraction sludge for sustainable agricultural waste management

Abstract

At the training farm of the Higher Institute of Agriculture, Forestry, Water resources and Environment of the University of Ebolowa-Cameroon, animal products and plant products are produced. Problem arises in the management of post-harvest crop residues and livestock effluent. To support their improved management, a local experimental study was conducted on the anaerobic co-digestion of chicken manure and sludge derived from banana pseudo-trunk fiber extraction. A batch mesophilic digester (36.33 ± 0.89 °C) with a working volume of 90 L was used. The substrate consisted of 20 kg of chicken manure, 40 kg of banana fiber extraction sludge, and 20 kg of water. Prior to digestion, the physicochemical characteristics of the co-substrates were analyzed, and biogas and digestate production were monitored throughout the process. Chicken manure showed a high dry matter content (85.8 ± 0.93%), was rich in organic matter (72.05% DM), and had a relatively high nitrogen content (Nt = 2.99 ± 0.18%; C/N = 10.4 ± 0.42). In contrast, banana fiber extraction sludge was highly liquid (95.37 ± 0.78% water), rich in organic matter (83.52% DM), and carbon-rich (C/N = 104.9 ± 4.61), making it significantly different but complementary to chicken manure. The overall substrate composition was 23.77 ± 0.39% DM, 17.39 ± 0.24% % OM, and 0.76 ± 0.05% total nitrogen. After 31.67 ± 0.89 days of digestion, 2.12 ± 0.10 Nm³ of biogas containing 64.65 ± 1.72% methane and 57.33 ± 2.22 kg of digestate were produced. Biogas productivity reached 188 ± 9 Nm³/t OM. These results demonstrate that co-digestion generates methane-rich biogas and nutrient-rich digestate, offering a sustainable solution for waste treatment, renewable energy production, and biofertilizer recovery.