Bacteriological Elimination in Sewage Sludge Through Direct Flow Convective Drying

摘要

Sewage sludge, one of the main components of the wastewater generated worldwide, is a residue with high moisture content. Because thermal drying allows volume reduction and microbiological inactivation, its use can be considered a powerful tool in the environmental area. The purpose of this study was to assess the drying process conducted with an upflow direct convection dryer for bacteriological disinfection by verifying the microorganisms E. coli and Salmonella spp, prior to and following the drying process. The study suggested that the most favorable drying condition occurred at the temperature of 140℃ and flow of 0.4 kg/min, while all the conditions applied to disinfection were also efficient, since the sludge was exposed to a temperature equal to or above 60℃ for more than 1 h in all the conditions, which exceeds the exposure time recommended for the death of the bacteria aforementioned.