Development and Validation of a Cassava Processing Waste Biogas Production Model for Rural Energy Supply in South East Nigeria

This study develops and validates a process model for biogas production from cassava processing waste in South East Nigeria, with the aim of providing reliable energy supply predictions for rural biogas system design. Cassava processing generates large volumes of organic waste including peel, press water, and bagasse that represent significant biogas production feedstocks. Rural cassava processing communities in Anambra, Imo, and Enugu States could significantly benefit from biogas energy derived from their processing waste, but system design requires validated production models for the specific waste characteristics of the region. This study conducts batch anaerobic digestion experiments using cassava peel, cassava bagasse, and cassava effluent at mesophilic (35 degrees Celsius) and thermophilic (55 degrees Celsius) conditions in laboratory-scale digesters at the Federal University of Technology Owerri. Biochemical methane potential tests determine maximum methane yield for each waste stream. A modified Gompertz kinetic model is fitted to cumulative methane production curves. A co-digestion experiment with 70:30 cassava peel to cow dung ratio is evaluated. Findings reveal that co-digestion significantly improves methane yield by 38 percent compared to mono-digestion of cassava peel. The validated model predicts methane production within 6 percent of measured values across all waste stream combinations. System design calculations demonstrate that a 500 kilogramme per day cassava processing centre can generate sufficient biogas to meet all facility thermal energy needs. The study recommends co-digestion biogas systems as the standard design for rural cassava processing centres.

Keywords: biogas production model, cassava processing waste, anaerobic digestion, rural energy, South East Nigeria.