VECCHIA, AD. et al. Assessment of enteric viruses in a sewage treatment plant located in Porto Alegre, southern Brazil. Braz. J. Biol. [online].
vol.72, n.4, pp. 839-846.
Trouble over (waste)water
The authors developed this study, in 2009, at the Laboratory of Molecular Microbiology, Institute of Health Sciences, Feevale University, in Novo Hamburgo, RS, analyzing the presence of enteric viruses in influent and effluent samples from a sewage treatment plant located in Porto Alegre, RS. The article was published in the Brazilian Journal of Biology, in November 2012.
The Brazilian regulations about the microbiological quality of water and wastewater do not include routine or preventive monitoring of enteric viruses; fecal coliforms are solely used as the microbiological indicators of fecal contamination. Viruses are known to have higher resistance than other microorganisms (including fecal coliforms) to the conventional protocols applied to the treatment of drinking water and wastewater derived from sewage. Thus, a given water sample may be free of detectable fecal coliforms but viruses may be present.
Enteric viruses may cause a wide range of clinical manifestation in human beings, from gastroenteritis to central nervous system illness. An eight months survey was conducted to examine the presence of human adenovirus (HAdV), enterovirus (EV), genogroup A rotaviruses (GARV) and Torque teno virus (TTV) in influent and treated effluent samples from the São João/Navegantes sewage treatment plant, located in Porto Alegre (Brazil).
Regardless of the month analyzed, all samples presented detection of genomes from at least one virus genus, except for one sample collected in April. Higher virus detection rates were observed in treated sewage samples (62.5 %), and in 80% of these were positive for the presence of HAdV. These results are pointing to the inefficacy of the current techniques applied to the treatment of sewage. Another problem is the lack of regulatory issues that may force the use of newer and more efficacious technologies for the removal or destruction of viral particles. All the effluents from this sewage treatment plant are discharged in water bodies, carrying a vast array of viruses; however, this wastewater is accomplishing the standards of the current legislation, since there are no rules for the preventive virological analysis of water and wastewater in Brazil.
To the knowledge of the authors, this is the first study showing the monitoring of viral genomes in influent and effluent samples from a sewage treatment sample located in Porto Alegre (Rio Grande do Sul, Brazil), Southern Brazil. The study had the financial support of the National Counsel of Technological and Scientific Development (CNPq) and the Coordination for the Improvement of Higher Level Personnel (Capes).
Fernando Rosado Spilki