Water solar disinfection using Escherichia coli and Clostridium perfringens as bioindicators / Desinfecção de águas naturais por radiação solar utilizando os bioindicadores : Escherichia coli e Clostridium perfringens

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

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.

ASSUNTO(S)

radiação solar saneamento ambiental solar radiation desinfection clostridium perfringens clostidium perfringens desinfecção escherichia coli escherichia coli

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