DOI: 10.11648/j.ajset.20261103.22 ISSN: 2578-8353

Assessment of Biogas Production from Anaerobic Co-Digestion of Kitchen Waste and Cow Dung

John Agori, Lucky Umukoro, Jeff Oba, Solomon Okoroafor, Ezekiel Obayehagweme, Enifome Eseha, Moses Utoyo
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Kitchen waste from commercial food-service establishments is a largely untapped renewable-energy resource in Nigeria, where roughly 43.5% of the population lacks access to grid electricity. This study evaluated the anaerobic-digestion potential of kitchen waste generated at a commercial restaurant in Oleh, Delta State, Nigeria, and the effect of co-digestion with cow dung on biogas yield and quality. Feedstocks were characterized for pH, moisture content, total solids, volatile solids, ash and carbon-to-nitrogen ratio, then batch-digested for 40 days in a completely randomized design with three treatments in triplicate: cow dung only, kitchen waste only, and a 50:50 mixture. Kitchen waste was acidic (pH 5.51–5.62), with 35.68–36.05% moisture, 61.25–61.64% volatile solids and a C/N ratio of 22:1, whereas cow dung was near-neutral (pH 6.05–6.18) with 80.95–81.32% volatile solids. Cumulative 40-day biogas yields were 169.4 L (4.24 L/day) for cow dung, 201.8 L (5.05 L/day) for kitchen waste and 243.6 L (6.09 L/day) for co-digestion. Co-digestion increased cumulative production by 20.71% over kitchen-waste mono-digestion, raised methane content from 62.1% to 67.2%, and increased calculated methane recovery from 125.32 L to 163.70 L (+30.63%), equivalent to 4.51 MJ and 5.89 MJ of cooking energy per batch at 36 MJ/m 3 . All treatments produced gas within the 50–70% methane band of healthy digestion and above the ~45% flammability threshold. Paired t-tests confirmed significant differences between the feedstocks for all measured parameters (α = 0.05). Co-digestion of commercial kitchen waste with cow dung offers a viable, low-cost, decentralized waste-to-energy option for food-service establishments, with the nutrient-rich digestate available as a soil amendment.

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