Water samples taken at 14 of Portugal’s Waste Water Treatment Plants (WWTPs) shows that two viruses in particular are able to emerge in treated water which is introduced back into the pubic system.
An investigation carried out by experts from the Faculty of Pharmacy of the University of Coimbra concludes that "the current methods used are not effective in removing the most resistant viruses."
"Analysis carried out on samples collected at 15 WWTPs from north to south of the country" revealed that "there are high amounts of genetic material from some viruses, such as polyomavirus JC and Norovirus," reports the university team.
Polyomavirus JC is little known, very common among the human population but only causes disease in individuals who have a very compromised immune system. It can trigger Multifocal Progressive Leukoencephalopathy, "a central nervous system disease that can be fatal."
The Norovirus group is the main one responsible for gastroenteritis and can be transmitted through the ingestion of contaminated food or water.
The idea of the study was to find out which viruses resisted treatment, since there is no legislation at national or European level to regulate the presence of viruses in treated wastewater.
The study focused on detecting and quantifying the existence of the most resistant viruses, "in order to draw the attention of the relevant authorities and policy makers to the need to include virus assessment in the WWTPs, in order to avoid risks to human health," said Ana Miguel Matos, study coordinator and teacher at the Faculty.
"The effluents from WWTPs are released into the water resources for reuse, and can be a way of transporting these viruses to the population," the researcher points out.
"We do not intend to cause alarm, but want to produce information that leads to new practices for assessing the quality of water leaving the WWTP so as to prevent the spread of viruses," said Matos.
The researchers verified that these viruses in the treated water were there even though different treatment methods were being used.
The next phase of the study will be to verify if these two viruses resist an innovative method of wastewater treatment being developed by a team of researchers from the Department of Chemical Engineering of the UC School of Science and Technology.
The method in question combines the use of photocatalytic ozone and biofilters with a freshwater clamshell known as Asian clams (Corbicula fluminea) to remove viruses and bacteria from the wastewater.
