To evaluate the infectious risk of norovirus (NoV) in various applications of the reclaimed water, five types of ultrafiltration (UF) membrane treatments were considered: (1) coagulation with low pH + UF membrane process, (2) UF membrane process alone, (3) UF + ultraviolet (UV) irradiation process, (4) UF + nanofiltration (NF) membrane process, and (5) UF + reverse osmosis (RO) membrane process. These treatments were used in a pilot plant and the NoV concentration after each treatment process was studied over the long term (2010–2014). Infectious risk was described using disability-adjusted life-year (DALY) when the reclaimed water was applied for agricultural irrigation, landscape irrigation, recreational enhancement, and toilet and urinal flushing. The results show that reclaimed water could be considered acceptable for recreational enhancement by adding a UV, an NF membrane, or an RO membrane treatment to the UF membrane treatment process. The water samples were concentrated according to the polyethylene glycol sedimentation (PEG) method. The genomes of NoV genotypes GI and GII were quantified with a real-time PCR detector (LightCycler DX400, Roche Diagnostics). The specific primer and TaqMan probes for NoV GI and GII used in the real-time polymerase chain reaction (PCR) were described in a previous study ( Kageyama et al. The standard curve was generated using 10-fold dilutions of plasmid DNA. For initial denaturation, the conditions of the real-time PCR were a temperature of 95 ☌ for 15 min, followed by 45 cycles of 95 ☌ for 30 s and 56 ☌ for 60 s. ![]() The details of the water sample concentration, RNA extraction, and related procedures were described in a previous study ( Yasui et al. In this study, the standard curve was created for each measurement of NoV and the copy number was calculated. At that time, it was confirmed that the amplification efficiency was 95% or more and the R 2 value was 0.9 or higher. Moreover, it was confirmed that the influence of inhibitors can be reduced in the method used. ![]() In the current case study, it was assumed that the reclaimed water provided by the Naha wastewater pilot plant is used as municipal water in central Naha City. Table 1 shows the applications of the reclaimed water, as well as the exposure frequencies of each application.
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