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AQUACAT Résumé de rapport

Project ID: ICA3-CT-2002-10016
Financé au titre de: FP5-INCO 2
Pays: Switzerland

Photocatalytic deactivation of bacteria by suspended and deposited titania

The efficiency of solar disinfection by heterogeneous photocatalysis was measured. The disinfection was performed with sol-gel immobilized TiO2 films over glass rings. Spring water naturally polluted with coliform bacteria was exposed to sunlight in plastic bottles in solar collectors and the disinfection effectiveness was measured. Total and fecal coliforms quantification was performed by means of the definite substrate method in order to obtain the efficiency of each technique. An important part of this study has been to determine the bacterial regrowth in water after disinfection by heterogeneous photocatalysis. The disinfection with TiO2 turned out to be more efficient than the current method of SODIS for total coliforms as well as for fecal ones. In a sunny day (more than 1000 W/m 2 irradiance), the disinfection with immobilized TiO2 needed fifteen minutes of irradiation to reduce the fecal coliforms content to zero and thirty minutes for total coliforms, less than half times required using SODIS. Bacterial regrowth of total coliforms was observed for SODIS disinfection, more frequently than for fecal coliforms. In contrast, when using the catalyst TiO2 no regrowth was detected, neither for total nor fecal coliforms. The disinfection process using TiO2 keeps water free of coliforms at least for seven days. The demonstration opens the possibility of application of this simple method in rural areas of developing countries. Other possible use is in disinfection of water in short periodes of time in zones where the distribution systems are collapsed by extreme weather phenomena.

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Reported by

EPFL - Ecublens
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