Feasibility of increased biogas production from the co-digestion of agricultural, municipal, and agro-industrial wastes in rural communities

In rural communities, such as Olds, Alberta (population 7248) energy may be produced through anaerobic co-digestion of municipal, agricultural, and agro-industrial wastes. An inventory within a 20 km radius of Olds revealed that 291 000 tonnes of wet organic waste are generated annually (96.8% manure) with an electrical potential of 42 GWh (1 GWh = 10⁶ kWh). Analysis of feedlot, hog, dairy and poultry manure, offal, food, grass, and biosolids identified the potential for waste blending to optimize solids content, nutrient balance, and pH level. In laboratory tests, biogas yield increased from 0.382 m³/kg volatile solid (VS) for feedlot manure alone to 0.513, 0.517, and 0.500 m³/kg VS with co-digestion of 30% hog manure, 15% offal, and 30% offal, respectively. Methane content of biogas increased from 75.8% in feedlot manure digestion to 78.8, 79.5, and 80.9% with co-digestion of 30% hog manure, 15% offal, and 30% offal, respectively.