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Tratamento de águas para consumo humano: um episódio de sobrevivência de cianobactérias
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Abstract(s)
No verão de 2015 ocorreu um episódio de mau odor/sabor na água de
abastecimento proveniente da albufeira do Roxo. Este episódio foi atribuído
à presença de um bloom cianobacteriano que incluía espécies
produtoras de compostos voláteis (geosmina, MIB). De facto, foi detetada
a presença de cianobactérias na água tratada, à saída da ETA, ainda
que em densidades relativamente baixas. No entanto, desconhecia-se
se estes organismos mantinham a viabilidade celular e a capacidade de
se desenvolver na rede de distribuição, a jusante da ETA e, desta forma,
contaminar a água para consumo humano. Assim, amostras de água colhidas
à saída da ETA e no Reservatório de abastecimento público foram
inoculadas em meio de cultura e o crescimento celular foi seguido por
microscopia ótica. Após 30 dias, verificou-se o crescimento algal, o que
demostra que algumas espécies resistiram ao tratamento na ETA e mantiveram
a capacidade de se reproduzir. Curiosamente, uma dessas espécies
foi o Cylindrospermopsis raciborskii, considerada até há pouco
tempo uma espécie tropical. Irá proceder-se à caracterização molecular
e toxigénica desta espécie. Atualmente está a decorrer um protocolo de
colaboração entre o Instituto Nacional de Saúde Doutor Ricardo Jorge e
a AgdA, com o objetivo de se estudar a distribuição de cianobactérias,
cianotoxinas e compostos voláteis na albufeira do Roxo.
In the summer of 2015 an unpleasant odour/taste occurred in the water for human consumption supplied from Roxo Reservoir. This episode was attributed to the presence of a cyanobacterial bloom composed by species producing volatile compounds (geosmin, MIB). In fact, cyanobacteria were detected in treated water, at the exit of Water Treatment Plant (WTP), although at relatively low densities. However, it was unknown if these organisms maintained their viability and the growth capacity in the distribution network and, as such, to contaminate the drinking water. Thus, treated water samples collected at the WTP and at the water deposit were inoculated in culture medium and cell growth was followed by optical microscopy. Algal growth was observed 30 days after culturing, which shows that some species resisted the treatment in the WTP and maintained the capacity to reproduce. Interestingly, one of those species was Cylindrospermopsis raciborskii, considered until recently a tropical species. Molecular and toxigenic characterization of this species will be carried out. A collaboration protocol between INSA I.P. and AgdA, is currently being carried out with the aim of studying the distribution of cyanobacteria, cyanotoxins and volatile compounds in the Roxo reservoir.
In the summer of 2015 an unpleasant odour/taste occurred in the water for human consumption supplied from Roxo Reservoir. This episode was attributed to the presence of a cyanobacterial bloom composed by species producing volatile compounds (geosmin, MIB). In fact, cyanobacteria were detected in treated water, at the exit of Water Treatment Plant (WTP), although at relatively low densities. However, it was unknown if these organisms maintained their viability and the growth capacity in the distribution network and, as such, to contaminate the drinking water. Thus, treated water samples collected at the WTP and at the water deposit were inoculated in culture medium and cell growth was followed by optical microscopy. Algal growth was observed 30 days after culturing, which shows that some species resisted the treatment in the WTP and maintained the capacity to reproduce. Interestingly, one of those species was Cylindrospermopsis raciborskii, considered until recently a tropical species. Molecular and toxigenic characterization of this species will be carried out. A collaboration protocol between INSA I.P. and AgdA, is currently being carried out with the aim of studying the distribution of cyanobacteria, cyanotoxins and volatile compounds in the Roxo reservoir.
Description
Keywords
Águas para Consumo Humano Cianobactérias Albufeira do Roxo Água e Solo Ecotoxicologia de Cianobactérias Segurança Alimentar Saúde Pública Portugal
Pedagogical Context
Citation
Boletim Epidemiológico Observações. 2016;5(Supl 8):56-58
Publisher
Instituto Nacional de Saúde Doutor Ricardo Jorge, IP