Influence of Temperature and Time on Pathogens Present in Biosolids Compost.

The biosolids produced in large quantities by Wastewater Treatment Plants (WWTPs) are a residue which has its final destination still debated and questioned by the technical sector and also by the authorities. One of the main obstacles to the free land application of biosolids as an organic fertilizer and soil conditioner is in the presence of pathogens. Composting is an alternative for inactivation of these pathogens, allowing the agricultural use of biosolids. This study aimed to evaluate the decay of thermotolerant coliforms, Salmonella spp. and viable Ascaris spp. ova during a 45-day composting under increasing temperatures, which exceeded 65ºC, and decreasing moisture indexes over time. For Salmonella spp. it is possible to be concluded the absence on the most of the time of the evaluated composting process. The group of thermotolerant coliforms presented a considerable drop in the values observed after 20 days of study, when the temperature reached 65ºC. Viable Ascaris spp. ova could still be found, with no decreases, under temperatures up to 65º C, then its survival started decreasing until the end of the composting process, when no egg remained viable.