Pilot scale thermal treatment of pig slurry for the inactivation of animal virus pathogens

This paper describes a pilot scale treatment plant that has been designed and built for the thermal inactivation in pig slurry of two viruses that infect pigs--African swine fever virus (ASFV) and swine vesicular disease virus (SVDV). The plant treats pig slurry continuously at a rate of up to 100 litres/hour and functions by heating the slurry, maintaining at least 99.99% of the slurry at the required temperature for a minimum period of 5 minutes, and then recovering the heat to raise the temperature of the incoming slurry. Results obtained indicated that SVDV was inactivated in pig slurry to below detectable levels with an alkaline pH (pH 7.5 to 8, as is usually the case) at a temperature of between 50 and 55 degrees C. In acidified slurry (pH 6.4), inactivation occurred between 55 and 60 degrees C. The difference in inactivation temperatures was probably due to the presence of free ammonia in the unacidified slurry. ASFV was inactivated by operating the plant at a temperature of 53 degrees C at a pH of 8.