PERFORMANCE EVALUATION OF ANAEROBIC CO-DIGESTION OF PIG DUNG AND POULTRY DROPPINGS FOR BIOGAS PRODUCTION IN A BATCH DIGESTION SYSTEM

Abstract

The rapid expansion of livestock production in Nigeria has led to the generation of large quantities of organic waste, presenting significant environmental and waste management challenges. Anaerobic co-digestion offers a sustainable approach for converting mixed livestock wastes into renewable biogas while simultaneously addressing waste disposal concerns. This study evaluated the biogas production performance of co-digested pig dung and poultry droppings at Vision Farm, Ogbeke Nike, Enugu State, Nigeria (6.52°N, 7.55°E). A batch anaerobic digestion experiment was conducted using a 3.5 m³ PVC biodigester. The digester was charged with 656.26 kg of mixed substrates diluted with 1968.75 L of water at a water to waste ratio of 3:1, with 75% of the digester volume occupied by slurry and the remaining 25% serving as gas headspace. Biogas production was monitored daily for 30 days using the water displacement method. Ambient temperature, slurry temperature, and slurry pH were recorded daily. Cumulative biogas production reached 6452.6 L with an average daily yield of 215.1 Ld⁻¹. Peak production of 571.5 L was recorded on day 14. Ambient temperature ranged from 30.5 - 37.0 °C, slurry temperature from 35.0 - 47.0 °C, and pH from 6.03 to 6.90, all consistent with favorable mesophilic conditions for methanogenic microbial activity. Flammable gas was confirmed from day 8, indicating active methane formation. These results demonstrate that anaerobic codigestion of pig and poultry wastes can effectively generate renewable energy for farm applications under tropical conditions.