Mathematical Modelling of Solid Waste Generation and Recycling Potential in Ibadan Metropolis

Municipal solid waste management in Ibadan, the capital of Oyo State in South West Nigeria and one of the largest cities in sub-Saharan Africa, faces mounting pressure from rapid urbanisation, increasing per capita waste generation, and constrained landfill capacity. This study develops a regression-based mathematical model of daily solid waste generation at the household and commercial district level, calibrated from a physical waste characterisation study conducted across eight residential density zones and four commercial districts. Independent variables include household size, income quintile, proximity to markets, and commercial activity index. The characterisation study further estimates the recyclable material fractions in the waste stream: plastics, metals, paper, glass, and organic matter. A linear programming model optimises the allocation of recovered recyclable material volumes across four potential processing pathways: informal sector recyclers, formal plastic pelletising facilities, composting for urban agriculture, and energy recovery. Results indicate that Ibadan generates approximately 4,200 tonnes of solid waste daily, of which 38 percent is organic matter suitable for composting and 22 percent is recyclable materials. The optimised processing allocation generates an estimated 1.8 billion naira in annual recyclate revenue while diverting 57 percent of waste from landfill disposal. Keywords: solid waste modelling, recycling optimisation, Ibadan, waste characterisation, linear programming.