During the drying process, the ejection shafts swirl the sludge into a constant cloud and the 572°F (300°C) hot air which circulates around, acting on all the sludge material simultaneously. The sludge is completely sanitized by the high temperature. Microbiological testing even confirms extensive sterilization of the dried sludge, which complies with EPA standards for Class A Biosolids and Exceptional Quality (EQ). Stated in the EPA Part 503 Rule, “this is characterized as biosolids that meet low-pollutant and Class A pathogen reduction (virtual absence of pathogens) limits.”
Pathogens which exist in the sludge are completely destroyed by the drying procedure. During subsequent use as a fertilizer and land application, there is no risk that pathogens can re-enter the human cycle.