Performance of wastewater reclamation systems in enteric virus removal.

Analysis of virus removal by tertiary or advanced sewage treatment processes is an emerging topic due to importance of reusing water on a global level. This study aimed to monitor important human viral pathogens: the human adenovirus (HAdV), JC polyomavirus (JCV) and Species A rotaviruses (RVA) in urban sewage, secondary effluents and reclaimed water from metropolitan São Paulo (MSP), Brazil. Four large wastewater treatment plants (WWTPs) in MSP were sampled monthly during a one-year period (April 2015 to March 2016). The viruses were quantified by quantitative PCR (qPCR), and HAdV viability was tested by the integrated cell culture (ICC)-qPCR assay. WWTPs are composed of activated sludge processes and different tertiary treatments (coagulation/sedimentation, sand-anthracite filters, membrane bioreactors (MBRs)/reverse osmosis (RO) and disinfection by chlorination). Physicochemical parameters were also evaluated to verify association with density of viruses detected in different treatment stages. HAdV, JCV and RVA were consistently detected (100%) in the sewage influent samples (range: 106-108 genome copies GC/L). In the secondary effluent, HAdV was detected in 100% (48/48) of the analysed samples, JCV in 85.4% and RVA in 97.9% (range: 104-107 GC/L for all viruses tested). HAdV was the most frequently detected virus in the tertiary effluent (62.2%) (28/45), exhibiting a viability between 0 and 44% of the tested samples in the wastewater reclamation systems. The MBR/RO systems demonstrated better virus removal efficiencies (range: 2.3-2.9 log10). Temperature, pH, turbidity and total organic carbon presented association with the viral density in the reclaimed water samples. Presence of viruses in treated effluents can indicates health risks depending on uses of recovery water. Further risk assessment studies should be conducted to better assess health risks under different exposure scenarios for water recovery in urban settings.

Noroviruses in raw sewage, secondary effluents and reclaimed water produced by sand-anthracite filters and membrane bioreactor/reverse osmosis system.

The importance of noroviruses (NoVs) in the epidemiology of waterborne diseases has increased globally in the last decades. The present study aimed to monitor genogroup I and II noroviruses in different treatment stages of four wastewater treatment plants (WWTPs) in the metropolitan São Paulo. WWTPs consist of secondary (activated sludge) and tertiary treatments (coagulation, sand-anthracite filters, membrane bioreactor (MBR)/reverse osmosis (RO) and chlorination). Raw sewage (500mL) and treated effluents (1L) were concentrated by celite and reclaimed water (40L) by hollow-fiber ultrafiltration system. Quantitative (qPCR) and nested PCR with nucleotide sequencing were used for quantification and molecular characterization. NoVs were widely distributed in raw wastewater samples (83.3%-100% NoV GI and 91.6%-100% NoV GII) and viral loads varied from 3.8 to 6.66log10gcL-1 for NoV GI and 3.8 to 7.3log10gcL-1 for NoV GII. Mean virus removal efficiencies obtained for activated sludge processes ranged from 0.3 to 0.8 log10 for NoV GI and 0.4 to 1.4 log10 for NoV GII. NoVs were not detected in the reuse water produced by MBR/RO system, while sand-anthracite filters resulted in a NoV GI and GII decay of 1.1-1.6 log10 and 0.7-1.6 log10, respectively. A variety of genotypes (GI.2, GI.3a, GI.3b, GI.5, GII.1, GII.4 Sydney 2012, GII.5, GII.6, GII.17) was observed, with a predominance of GI.2 and GII.17 in the different genogroups. These results corroborate with recent data about the entry and dissemination of the emerging genotype GII.P17-GII.17 Kawasaki 2014 in the country, and may indicate a change in the epidemiological patterns of norovirus strains circulation in this region. This is the first large-scale study to evaluate burden and genotypes of noroviruses in WWTPs in Brazil, providing a rapid diagnosis of viruses circulating in the population.