An Assessment of Biogas Production from Food Waste Obtained from School Feeding Programme

Global electricity demand has risen sharply, increasing the need for cost-effective, sustainable energy alternatives. In South Africa, reliance on fossil fuels worsens global warming. The Bongumusa Secondary School in Mpumalanga province consumes 500 kg of firewood weekly for student meals, while organic waste disposal in landfills further drives greenhouse emissions. This study designed, constructed, and evaluated two low-cost 0.21 m³ polyethylene pilot biogas digesters fed with school food waste. To assess environmental impacts, one digester was installed above ground and the other was buried underground. Parameters measured included pH, total solids (TS), volatile solids (VS), and biogas composition over a 30-day retention period. The underground digester achieved a 62% methane yield. Conversely, the surface digester yielded only 42% methane due to ambient temperature fluctuations. For the underground digester, biogas production occurred between days 14 and 17 at an optimal pH of 6.9 and an average temperature of 35°C.