Desinfecção de águas naturais por radiação solar utilizando os bioindicadores : Escherichia coli e Clostridium perfringens
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Data
2008-08-25
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Universidade Federal de Goiás
Resumo
Latin-American countries are facing serious problems related to waterborne diseases due to
the lack of basic sanitation, affecting in particular those people living in small and rural
communities. Solar radiation for water disinfection, SODIS, seems a promising process for
small communities since it does not require electric energy and it has low cost and easy
operation. This work aimed to evaluate the inactivation of the pathogens Escherichia coli and
Clostridium perfringens by SODIS in the Center-West region of Brazil, Goiânia-GO. The
Colilert® and multiple tubes (NMP/100 mL) were used to determine the Escherichia coli and
the Clostridium perfringens bacterias, respectively. The inactivation and the re-growth of
these bioindicators, the physico-chemical parameters of the raw and disinfected waters were
the main focus of this work. Raw water was collected from a well located at the Civil
Engineering School (EEC) of Federal University of Goiás (UFG) and it was inoculated apart
using pre-determined concentrations of these bio-indicators. Samples were put in transparent
PET bottles with capacity of 2L and left under sunlight exposure between 9am and 3pm.
Samples were collected and analyzed in the laboratory after 0, 2, 4 and 6 hours of exposure.
The work was divided into two phases: the first evaluate the effect of the use of two water
volumes (1.5 L and 2 L) on the pathogen inactivation. In addition, the re-growth of these
pathogens in the PET bottles after 3 storage days at ambient temperature was also investigated. In the second phase, PET bottles containing 1.5 L of contaminated water were
exposed to sunlight radiation with and without solar reflectors. The results showed that there
was a small difference (0,25-Log to Clostridium perfringens and 0,5-Log to Escherichia coli)
in the inactivation of both bioindicators between the two volumes evaluated in the first phase.
The use of the solar reflector did not improve the inactivation of the Clostridium perfringens
and their re-growth was proportional to the final concentration after 6 hours of sunlight
exposure.
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MORGADO, Waleska Fernanda Ferreira. Water solar disinfection using Escherichia coli and Clostridium perfringens as bioindicators. 2008. 59 f. Dissertação (Mestrado em Engenharias) - Universidade Federal de Goiás, Goiânia, 2008.