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Abstract
Edo State is one of Nigeria’s principal oil-palm processing corridors, hosting industrial plantations at Okomu and Presco, the research mill of the Nigerian Institute for Oil Palm Research at Benin City, and a dense belt of semi-mechanised and artisanal mills, including the Leventis facility at Weppa-Agenebode. These mills discharge palm oil mill effluent that is hot, acidic, and organically concentrated, and that remains largely untreated beyond open ponds. This study assessed whether POME generated within Edo State is chemically and operationally suitable as feedstock for anaerobic digestion and biogas recovery. Published physicochemical analyses of Edo mill effluent and bench- to pilot-scale digestion trials on Edo substrates were compiled and appraised against a six-criterion suitability rubric covering organic strength, biodegradability, buffering and co-substrate need, process configuration readiness, mill-scale accessibility, and energy-recovery cost. Co-digestion of POME with animal manure obtained the highest weighted suitability indices (4.25 for a 4:1 POME-to-cow-dung ratio and 4.10 for POME–poultry litter), with bench yields reaching 1,000 mL biomethane over 28 to 49 days under mesophilic conditions at NIFOR and 1,875 mL at a 70:30 POME-to-cow-manure ratio in a related Nigerian trial. Residue co-digestion at Weppa raised cumulative biogas from 80 mL on POME alone to 370 mL at 40 percent solids. Raw Edo POME is a genuine feedstock NIFOR and Presco COD values of approximately 59,815 and 44,100 mg L−1 place the liquor well inside the industrial digestion window but its pH of 4.4 to 4.5 and oil-and-grease load require alkalinity management or co-substrates. The study concludes that Edo State possesses an internally complete substrate base for mill-gate biogas, and recommends staged pilot digesters at NIFOR and Weppa followed by covered-lagoon retrofits at Okomu- and Presco-scale ponds.