The Removal Efficiency of Typical Opportunistic Pathogens by Advanced Treatment Process of Reclaimed Water and Health Risk Assessment

In this study, two combined processes of coagulation sedimentation-NaClO disinfection and coagulation sedimentation-ultrafiltration (UF)-NaClO disinfection are used as advanced treatment processes to explore the removal effect and mechanism of the combined processes on Legionella, Pseudomonas aeruginosa, Mycobacterium avium, and Escherichia coli in the secondary effluent. In addition, reclaimed water was reused in the landscape as an evaluation scenario, Monte Carlo simulation of the health risk of opportunistic pathogens in process effluent was carried out, and the microbiological safety of the two processes was evaluated. The results showed that the combined process of coagulation sedimentation-UF-NaClO has a good removal effect on Legionella, Pseudomonas aeruginosa, Mycobacterium avium, and Escherichia coli, and the removal rates are 99.8%, 98.6%, 99.4%, and 99.1%, respectively. There is 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 is no longer significant after the two combination processes. The three opportunistic pathogens has the lowest single-exposure infection probability after secondary effluent coagulation sedimentation-UF-NaClO disinfection and reuse for urban landscape leisure activities. The safety rate for human health may range from 70.9% to 100%.