Health risk assessment and removal efficiency of typical opportunistic pathogens by advanced reclaimed water treatment process

Abstract In this study, two combined processes of coagulation sedimentation-NaClO disinfection and coagulation sedimentation-Ultrafiltration(UF)-NaClO disinfection were used as deep treatment processes. To explore the removal effect and mechanism of the combined process on Legionella, Pseudomonas aeruginosa, Mycobacterium avium and Escherichia coli in the secondary effluent. Taking Beijing Olympic Forest Park as the evaluation scene of reclaimed water landscape reuse, the health risk assessment were carried out on the opportunistic pathogens. The results showed that the combined process of coagulation sedimentation-UF-NaClO had a good removal effect on Legionella, Pseudomonas aeruginosa, Mycobacterium avium and Escherichia coli, the removal rates were 99.8%, 98.6%, 99.4% and 99.1%, respectively. There was a significant positive correlation between the concentration of Escherichia coli in the secondary effluent and the three opportunistic pathogens, but the correlation between the concentration of Escherichia coli in the effluent and the three opportunistic pathogens was no longer significant after the two combination processes. After secondary effluent coagulation and sedimentation-UF-NaClO disinfection and reuse for urban landscape leisure activities, the single exposure infection probability of the three opportunistic pathogens is the lowest, and the safety rate of human health can reach from 70.9–100.0%.