Inactivation of enteric bacterial pathogens in sewage sludge by anaerobic digestion and dewatering treatment
城市污泥厌氧消化和脱水工艺对肠道病原菌的杀灭效应

This study investigated the quantities of three enteric bacterial pathogens, E.coli, Salmonella spp. and Shigella spp. through anaerobic digestion and dewatering treatment by using the most probable number (MPN) culture and quantitative real-time PCR (qPCR) methods. MPN results showed that the quantities of E. coli, Salmonella spp. and Shigella spp. decreased significantly after anaerobic digestion, and the average log reduction values were 2~5. However, the qPCR results showed the average log reduction values were 1~2. After dewatering treatment, the quantities of three pathogens in the sludge changed slightly and no phenomenon of regrowth after dewatering was observed. The concentrations of E.coli, Salmonella spp. and Shigella spp. were between 104~107, 104~105, and 103~105 MPN·g-1 (dry weight), respectively. The detection difference between the MPN and qPCR results indicated the existence of viable but non-culturable (VBNC) pathogens which resulted from anaerobic digestion treatment. This phenomenon suggested that the application of traditional culture methods should be careful for the bacterial pathogens detection and the biological safety assessment in sewage sludge discharge.