The start-up of the process using as inoculum a mixture of temperature adapted pig manure and sewage sludge (stored in anoxic conditions at environmental temperatures for a month), together with fresh rumen from a slaughterhouse, resulted in immediate biogas production, with production rates (5.4 L biogas day1) and yield (66.1 L biogas kg VS1), within the range of those reported in the literature. However, methane content in biogas (20%) was remarkably low even after 80 days, indicating that a longer adaptation period, of at least 3 months, is necessary to ensure initial methanogenic population development at ambient temperatures.