Solar radiation (UV-A and temperature) in the inactivation of Vibrio cholerae in water for human consumption. Factors that condition the efficiency of the process

Abstract

Vibrio cholera was inoculated in plastic and glass bottles and plastic bags. The containers were exposed to sunlight during six hours. When temperature raised-up to 30° C, 35° C, 40° C, and 45° C, samples of water were taken. The impact of: a) temperature, b) turbidity, c) container and d) initial concentration of vibrio were determined. The bacteria were inactivated with only temperature, when it raised up to 45º C, whereas, with constant temperature of 30º C it was necessary 100 Wh/m² of the radiation and at 50º C, only 10 Wh/m². The turbidity caused interference with SODIS process: total inactivation was achieved with different levels: 105 Wh/m² (40 TNU), 91 Wh/m² (23 TNU) and 36 Wh/m² (5 TNU). The container type and initial different concentration of vibrio did not have influence on the SODIS process. Full correlation among thermotolerant coliforms and V. cholerae inactivation was always high (0.86 and 0.99).