Interaction between E-coli inactivation and DBP-precursors -: dihydroxybenzene isomers -: in the photocatalytic process of drinking-water disinfection with TiO2

The common drinking water disinfection procedures lead to the formation of disinfection by-products (DBPs), which come mainly from naturally occurring organic compounds disinfection by-products precursors (DBPPs). Solar disinfection by photocatalysis is a promising method, which could be applied to a drinking water treatment process in order to destroy a bacterial population and DBPPs as well. The complete E, coli inactivation by light irradiation over TiO2 suspension was reached in 20 min, while by light alone it was in 70 min. Illumination was produced by a Hanau Suntest lamp simulating natural radiation power of 80 mW cm(-2). The addition of DBPPs like C6H4(OH)(2): hydroquinone, resorcinol and catechol to bacterial suspension contained TiO2, resulted in a decrease in sunlight germicidal activity. A correlation between photoreactivity of dihydroxybenzene isomers and photocatalytic bacterial disinfection was demonstrated. Experiments performed under dark conditions demonstrated either C6H4(OH)(2) or TiO2 separately do not affect to a large extent the survival of E. coli, while mixing of both showed a bacterial deactivation between two- and one-order of magnitude in the presence of substances within 2 h. The order of decay in photodegradability was resorcinol > catechol, hydroquinone. The evolution of C6H4(OH)(2) degradation under light in the presence of both oxygen and H2O2 as electron acceptor was discussed. (C) 2001 Elsevier Science B.V. All rights reserved.